Choosiong the Right Landscape Plants: Factors to …learningstore.uwex.edu/Assets/pdfs/A3864.pdfchoosing the right landscape plants usda cold hardiness zones 3a 3b 4a 4b 5b –35°to–40°F

A3864

Laura G. Jull

f a c t o r s t o c o n s i d e r

Choosing the rightlandscape plants

Choosing Plants 2:Layout 1 8/28/08 3:28 PM Page a

contents

Climat ic considerat ions 1

The plant ’s function inthe landscape 4

Size, form, and growthrate considerat ions 7

Ornamental considerat ions 10

Cultural considerat ions 14

Native habitat andinvasiveness 18

Selecting high-qual itynursery stock 19

References 20

For more information 20

List of scient if ic names 20

�Properly placed and

cared for landscape

plants can increase the

value of real estate.

However, poor plant

choices can become a

maintenance problem and

create an unsightly

landscape. Mismatched

cultural requirements,

improper planting (too

deep), and vandalism

account for more tree

and shrub deaths than

all insect and disease-

related deaths combined.

Always strive to plant

the right plant in the

right place.

�

Choosing Plants 2:Layout 1 8/28/08 3:28 PM Page b

Questions to consider are:

� What plants are adapted to my climate?

� How is the plant to be used in thelandscape?

� What are the space considerations ofthe site?

� How big does the plant get and howfast does it grow?

� Does the plant have showy flowers andfruit?

� Is the foliage colorful during thegrowing season or in autumn?

� Does the plant have interesting bark orbranches?

� What cultural requirements does itneed?

� Is the plant susceptible to insects ordiseases?

� Is the plant sensitive to air pollution ordeicing salts?

� What type of landscape maintenanceam I willing to provide?

� Are there any regulations or localordinances preventing me fromplanting?

� What existing vegetation exists in thearea? Are there any invasive plants?

� How do I know if I am purchasing high-quality nursery stock?

These questions, along with the selectioncriteria discussed in this publication,should provide the basis for yourlandscape plant choices. Choosing theproper plants for a landscape help toensure the plant has the best chance forhealthy growth, development, and long-term survival.

ClimaticconsiderationsClimateClimate is perhaps the most importantfactor when choosing landscape plants.The ability of a plant to adapt to a givenclimate is referred to as hardiness; itinvolves tolerance to both low and hightemperatures. It is very important to usespecies that can survive the temperatureextremes of your location. If the plant isnot tolerant to your particular winterconditions, a perennial will perform like anannual and die over winter.

Urban areas usually are slightly warmerthan rural areas due to the “heat island”effect created by heat from sewers andfurnaces. Heat that is trapped andsheltered by buildings and streets alsocontributes to this effect. In addition,unique microclimates can be created atspecific sites. For example, trees plantedclose to black asphalt pavement will havewarmer conditions in summer and willprobably need more water than thosesame plants planted in the middle of apark area. Some areas also may be subjectto early and late frosts, particularly sites athigher elevations and those in low areas orfrost pockets. In light of these differences,two very important climatic adaptabilitycriteria to consider when choosing plantsare USDA Cold Hardiness Zones andAmerican Horticultural Society (AHS) HeatZones.

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What plants are adaptedto my climate? ?�

Plant selection is one of the most

important decisions a gardener, landscaper,

or designer makes when landscaping.

�Note: This publication identifies plantsby their common names; if you’re interestedin learning more about a given plant, youmaywish to refer to the list on pages 20 and21 for the full scientific name to ensure thatyou’re looking up the same plant.

sunrise forsythia

Choosing Plants 2:Layout 1 8/28/08 3:28 PM Page 1

Cold hardinessUSDA cold hardiness zones are based onthe range of average annual minimumwinter temperatures. Lower zone numbersindicate colder climates; higher numbersindicate warmer climates.Wisconsin hasthree cold hardiness zones: zone 3(northernWisconsin), zone 4 (central andsouthwesternWisconsin), and zone 5(southeasternWisconsin). The hardinesszones are further divided into two sub-zones of either “a“ (the colder half of thehardiness zone) or “b” (the warmer). Forexample, the hardiness zone in Portage,Wisconsin, is zone 4b while Stevens Point,Wisconsin, is in zone 4a.This means that azone 4 hardy plant is cold hardy to –20°F to–30°F with further division of this zone intozone 4a (hardy –25°F to –30°F) or zone 4b(hardy –20°F to –25°F).

This subdivision is critical for estimatingcold hardiness of some woody plants.When in doubt as to whether you are inthe “a”or “b”part of a cold hardiness zone,it is better to err on the side of plants thatare hardy to the colder “a” zone.Winterhardiness is crucial in plant selection,health, and survival. Lack of hardiness canlead to dieback, decline in plant health,death of flower buds, or damage ordestruction to the entire plant. Forexample, the flower buds of borderforsythia are not cold hardy to zone 4b butthe flower buds of Sunrise forsythia arecold hardy; therefore, choosing cultivarsand species that are hardy to your area iscrucial.Many horticultural reference andgardening books and plant labels now listthe subdivision of the zones (“a” and “b”).When in doubt, ask a local nursery orgarden center for appropriate plants foryour area or contact your local countyExtension office for further information.

Heat toleranceAmerican Horticultural Society Heat Zonesare based on average annual days that areabove 86°F.Wisconsin has four heat zones:zone 2 (northeasternWisconsin along theUpper Peninsula of Michigan border),zone 3 (north central Wisconsin and DoorCounty), zone 4 (most of western, central,and easternWisconsin), and zone 5(extreme southern and westernWisconsin).Heat zones are particularly important inthe southern and western U.S., but also areimportant in the northern U.S. Forexample, paper birch and pagodadogwood, species preferring heat zonesbelow 5, are not suitable in some parts ofsouthernWisconsin, especially in urbanareas, and will not thrive in those locations.They are cool, woodland species native tonorthernWisconsin.They becomesusceptible to insects, such as bronze birchborer (birch) or golden canker (dogwood)when grown in the poor, dry soils and hightemperature extremes common in urbanand some suburban environments.

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c h o o s i n g t h e r i g h t l a n d s c a p e p l a n t s�

usda cold hardiness zones

3a

3b

4a

4b

5b

–35° to –40°F

–30° to –35°F

–25° to –30°F

–20° to –25°F

–15° to –20°F

–10° to –15°F

american horticultural societyplant heat zone map

Average number of daysper year above 86°F

Average annual minimumwinter temperatures

2

3

4

5

1–7 days

8–14 days

15–30 days

31–45 days

6 46–60 days

7 61–90 daysReproduced with permission of the American Horticultural Society(www.ahs.org).


High temperatures are important becausethey affect the supply of carbohydrates(sugars) plants manufacture for themselvesduring the day by photosynthesis. Plantsuse stored carbohydrates to produce newleaves, shoots, roots, and fruit. Sugars arealso involved in several physiologicalprocesses, and generate important plantpigments, such as anthocyanin (red, purple,and blue pigments).When plants withpoor heat tolerance are grown in regionsthat routinely experience high summerday and night temperatures, they often“burn up”much of their supply of storedcarbohydrates during the evening hours.

These conditions occur not only in warmerareas of the U.S., but can also take place inurban environments, containers, and cityboulevards. Plants like the purple-leafbeech offer an example.The tree haspurple leaves during the cooler parts ofspring and early summer, but whenexcessively high temperatures occur inwarmer heat zones of 6 and higher,respiration rates at night increase andthere are not enough carbohydrates(sugars) left over for purple pigment todevelop.The leaves can fade to a greenish-purple.This does not harm the plant butdefeats the purpose of growing thispurple-leaved tree in the first place.

Some trees will die due to excessively hightemperatures. Heat also increasessusceptibility to insects and diseases,especially wood-boring insects and rootrots. In these microclimates, the storedcarbohydrates are used for nighttimerespiration, leaving little for defenseagainst pests. Generally, for mostresidential locations, you do not have toworry about heat tolerance unless aspecies specifically requires a cooler orshady environment with adequatemoisture.

Provenance(geographic seed source)One other important adaptability criteriato consider when choosing plants isprovenance. Provenance refers to thegeographic origin of the seed. Provenanceis not an issue for vegetatively propagated(via cuttings, budding/grafting, tissueculture, layering) species and cultivars, butit is very important for some native andexotic species that have a wide, nativegeographic range and are primarilypropagated by seed.

You may not know whether a nursery orgarden center has obtained seed-propagated plant material from a northernseed source, but you can try asking. Forexample, eastern redbud is native fromNew Jersey to northern Florida, and westto Illinois and northern Mexico. Somegrowers have been known to collect seedor buy nursery stock of eastern redbudtrees growing in southern U.S. locations,such as Tennessee, and sell them innorthern markets.These seed-propagated,southern provenances of eastern redbudare less cold hardy and require a shorterdormancy to break bud. Consequently,plants grown from southern seed sourcesare prone to winter damage and maybreak bud early in spring,making themvulnerable to frost damage.

In contrast, the more northernprovenances have greater cold hardinessand should be chosen for use in the UpperMidwest when propagating or growingspecies such as eastern redbud.This mayalso hold true for non-native, exoticspecies.

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Trees best grown fromnorthern seed sourcesScientific name Common name

Acer rubrum Red maple

Asimina triloba Pawpaw

Betula nigra River birch

Carpinus caroliniana American hornbeamor musclewood

Cercis canadensis Eastern redbuda

Cornus florida Flowering dogwood

Fagus grandifolia American beech

Liriodendron tulipifera Tuliptree, tulip-poplar

Morella (formerly Northern bayberryMyrica) pensylvanica

Nyssa sylvatica Black gum, tupelo

Pinus ponderosa Ponderosa pine

Pseudotsuga menziesii Douglas-firvar. glauca

Quercus spp. Oaks (most)

Sassafras albidum Sassafras

Taxodium distichum Baldcypress

aRedbuds sold as “Columbus strain”or “Minnesotastrain” come from a northern provenance.

eastern redbud


The functional use of a plant in thelandscape is a centralconsideration when making plant

choices. Plants can function in multipleways in the landscape; this can make yourchoice even more difficult. Pay attention tothe particular features of different plants;these may give you ideas about where inthe landscape they might best be put touse. Here are some guidelines.

Shade treesHow dense do you want your shade to be?Trees that produce dense shade, such asmaples and oaks, should be planted wherethere is enough space, as well as sunlight.These species work well on the southeast,southwest, and west sides of buildings andhomes by providing cool shade in summer,which can significantly lower your coolingcosts. Deciduous trees drop their leaves inautumn which allows for the low,wintersun to shine through your windows,bringing heat and light into the home.

Street treesTrees that are to be planted along a streetshould tolerate heat, drought, poordrainage and aeration, soil compaction,low fertility, high pH, deicing salts, and airpollution.They should also be cold hardyto your area and resist pests. Street treesoften suffer greatly due to lack of waterand restricted rooting area; hence,selection of an appropriate species isimportant for the tree’s growth andsurvival.Maybe the best choice is not toplant a tree, but to select herbaceousperennials or annuals.

When planting a street tree, remember to“look up” for power lines and avoid plantingspecies that get large at maturity (tallerthan 30 ft.) near utilities. For example,many maples, oaks, honeylocusts, andlindens get too tall to plant near powerlines. However, if power lines are not aproblem and sufficient rooting area isprovided,many of these trees make goodstreet tree choices. Some oaks can makegood street trees if the acorn litter inautumn is not a serious issue.

SpecimensA specimen plant can stand alone in thelandscape and serve as a focal point.Theplant’s ornamentalcharacteristics drawyour attention to it. Itmay have a uniqueform or texture, showyfoliage, flowers, fruit, orinteresting bark orbranching. A specimenplant can be combinedwith other plants inmixed shrub orherbaceous perennialborders.Many small, ornamental trees arespecimen plants such as floweringcrabapple and Japanese tree lilac.

ScreensPlants can be used to eliminate anundesirable view, smell, block noise, or trapdust and debris from roads.They alsooutline space and create outdoor spaces or“rooms” in the landscape and provideprivacy. Usually, a single species with adense habit is planted in a row, preferablyevergreens with low branches. Sometimesberms (elongated mounds) are used toscreen views.The plants can be shearedinto a tall hedge (see next page underhedge), or allowed to spread naturally.Most evergreen trees such as pines, spruce,fir, Douglas-fir, eastern hemlock, northernwhite-cedar, and eastern red-cedar lookbest if allowed to grow naturally and canserve as very effective screening plants inthe landscape.

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Good choicesfor street trees

Scientific name Common name

Short trees (suitable near power lines)

Malus spp. Flowering crabapples

Syringa reticulata Japanese tree lilac

Tall trees (not suitable near power lines)

Acer miyabei ‘Morton’ State Street®Miyabe maple

Acer x freemanii Freeman maple

Ginkgo biloba Ginkgo (male cultivars)

Gleditsia triacanthos Honeylocust (malevar. inermis cultivars)

Quercus muehlenbergii Chinkapin oak


Tilia spp. Lindens

Ulmus spp. Elms (hybrids)

The plant’s functionin the landscape

How is the plant to be usedin the landscape??

ivory silkjapanese

tree l ilac

compact americancranberrybush viburnumcompact americancranberrybush viburnum


WindbreaksPlants can serve to reduce the force of thewind.Windbreaks are often made up ofone species planted in a single row, ormultiple species planted in several rows.Evergreens are a better choice forwindbreaks as they retain their leaves inwinter when cold winds are at their worst.Evergreens also serve as a screen to blockviews (see above under screen). Evergreenwindbreaks can provide cover for wildlife,particularly in winter.

HedgesA hedge is a living green fence usuallyconsisting of one species, often plantedclose together in a single or double rowwith alternate spacing. Hedges help defineor divide portions of your property ordirect pedestrian traffic. They can beornamental or defensive (barrier) and canbe trimmed to produce a tight, formalappearance or allowed to grow naturally,creating an informal effect. Evergreensused as hedge plants can also serve as ascreen.

For formal hedges, choose evergreenspecies that can tolerate shearing andhave dormant buds along the stem thatcan break and re-grow. Such speciesinclude boxwood, yews, arborvitae orwhite-cedar, or eastern hemlock. Avoid useof junipers, spruces, and most pines intightly clipped hedges as these plantsgrow mainly from the tips of brancheswhere the buds are formed.Yearly,repeated trimming of these shrubs to thesame point will result in dead tissue,unsightly plants, and poor performance.

Do not shear ornamental flowering shrubssuch as forsythia, lilacs, dogwoods, orspirea into formal hedges, as you will beremoving flower buds. Flower buds arecommonly formed in mid to late summerfor the following spring season.These andother deciduous or evergreen species canbe used as informal hedges where theirnatural shape is retained and they are notsheared. Avoid the use of tallhedgebuckthorn and Tatarian honeysuckle ashedge plants. Both species are highlyinvasive in woodlands, prairies, andwetlands.

BarriersA barrier plant is typically a defensivehedge to keep objects away and deter foottraffic. Barrier plants usually have thorns orare quite twiggy, with sharp branches.Shrub roses, barberry, and hawthorn aresome examples of plants that makeeffective barriers.

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Hedges, barriers,and screens


Screens (best if allowed to grow naturally)

Abies spp. Firs

Juniperus virginiana Eastern red-cedar

Picea spp. Spruces

Pinus spp. Pines

Pseudotsuga menziesii Douglas-firvar. glauca

Thuja occidentalis Arborvitae, white-cedar

Tsuga canadensis Eastern hemlock

Formal hedges (tolerates shearing)

Buxus spp. Boxwoods

Taxus spp. Yews

Thuja occidentalis Arborvitae, white-cedar


Informal hedges (do not shear)

Cornus spp. Dogwoods

Forsythia spp. Forsythias

Spiraea spp. Spireas

Syringa spp. Lilacs

Barriers

Berberis spp. Barberries

Crataegus spp. Hawthorns

Rosa spp. Shrub roses

barrier (shrub rose)

formalhedge (yew)

informalhedge (yew)


BordersShrub borders are often planted along theperimeter of a house or in landscape bedsthat define boundaries; for example, theline between your yard and yourneighbor’s.You can create a mixed borderusing both woody and herbaceousperennials.

EdgingEdging refers to planting of low-growingspecies along the margin of a landscapebed, helping to define a border. It cancomprise one or more species and theplants typically grow less than 3 feet tall.Boxwood and Crimson Pygmy Japanesebarberry are commonly used for edging.

FoundationFoundation plants can be individual plantsor combinations of plants placed next tohomes and buildings to soften thestructure.To allow access to windows andclearance near awnings, plants selected asfoundation plants usually grow lower than6 feet tall. Plant taller or wide-spreadingtrees and shrubs away from windows andentranceways to allow people to pass.

MassesA mass planting consists of a number ofplants, either the same or a combination ofspecies, planted close together that oftenscreen a view. If they are tall enough,masses can provide a windbreak. Bothevergreens and flowering shrubs can beused in masses.Make sure you do notcrowd the plants together as plants placedtoo close together will shed their innerleaves and branches to compensate forreduced light levels.

GroundcoverA groundcover is a flat or trailing plant thatspreads along the ground. It creates the“floor”of the landscape and can helpprevent erosion and stabilize slopes orbanks. Some groundcovers can toleratedeep shade like Japanese pachysandra,while others require full sun like junipers.Groundcovers are usually evergreen, butthere are some flowering groundcoverssuch as sweet woodruff and creepingphlox.

VineVines climb by special adaptations such astendrils, tendrils with adhesive discs at thetips, rootlets (adventitious roots), or bytwining around a structure or fence.Vinescreate the “walls” and “ceilings”of thelandscape as they can be used on walls,trellises, or allowed to grow over arbors orpergolas. Some vines, such as Orientalbittersweet and English ivy, are invasiveand choke out trees and other plants asthey climb over them. Avoid planting thesespecies. American bittersweet is a goodalternative, native, non-invasive vine thatcan be used instead of Orientalbittersweet. Some vines have beautifulflowers such as Kentucky wisteria andsweet autumn clematis.

Container plantsSome shrubs and a few, smaller trees canbe grown outdoors in insulated containers,provided they receive enough light withconsistent watering, adequate drainage,and pruning during the growing season.Containers can be used in tight spaces, onpatios, decks, or in areas where a splash ofcolor is needed. A few trees that can begrown in containers include Cinderella®,Firebird®, and Tina crabapples.

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c h o o s i n g t h e r i g h t l a n d s c a p e p l a n t s�

foundation(saybrookgold juniper)

border(alp ine currant)


When making your plantselection, it’s important tothink about how tall and

wide the plant will ultimately become andwhether it will still fit your space years later.

SizeTrees and shrubs typically are plantedwhen young.Take care to consider howtheir growth will impact the landscape inthe future.Too often, the mature heightand width of tree and shrub branches androots are not taken into consideration.Utility lines, both above and below ground,sewers, light posts, sidewalks, roads, andother structures should be considered asyou decide how large a tree or shrub toplant. Power and construction companieswill be forced to prune back your plants ifthey are too large and become anobstruction. Also, remember vehicular andpedestrian traffic.More maintenancepruning will be required to preventobstruction of view and unsafe conditionssuch as thorny or prickly foliage thatextends over the street or sidewalk,messyfruit that creates slippery walkways, andspreading branches that prevent driversfrom seeing traffic.

Avoid crowding plants together orplanting trees too close to buildings, eventhough this may be visually appealing atfirst.You will eventually have to remove orrelocate plants that get too big for thearea. Large trees planted too close to abuilding can cause infrastructure orfoundation damage from the roots andbranches and become a liability.

FormYou need to be aware of the plant’s formand branching characteristics. (Commonplant forms are pictured on pages 8 and 9.)Form and branching refers to the plant’soverall size, shape, and outline. For narrowspaces, choose plants that have a columnaror fastigiate form,with larger, vase-shapedor spreading trees in bigger areas.Mosttrees are pyramidal when young andbecome rounded or open with age. Ingeneral, pick trees that have a balancedand attractive branch pattern. Look for

wide crotch anglesbetween the branches andthe main trunk of the treeto avoid large limbbreakage later. Don’t forgetto consider the size of theroot system of the matureplant. Roots often requiremore space than mostpeople think.

Growth rateA plant’s genetic makeup, the length of thegrowing season, and the attention given tothe plant’s culture will determine howquickly a tree or shrub grows. A fast-growing tree may be important whenplanting for shade or screening. However,some fast-growing species have weakwood, poor branch attachment, and areprone to storm breakage. Silver maples,willows, and Siberian elm are subject tothis problem and need more frequentpruning. Slow-growing trees and shrubssuch as ginkgo and Koreanspice viburnummay be beneficial near streets and homes,because of fewer maintenance (pruning)requirements.

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Size, form, and growth rateconsiderations

What are the spaceconsiderat ions of the site? ?

How big does the plant get andhow fast does it grow??


arching: Branches on tree or shrubarch over, creating a fountain orcascading look.

climbing: Stems of a plant growupwards along a fence, trellis, wall, orother structure; common in vines.

clump: Main branches or multipletrunks of a tree arise from the base ofthe plant. Common in ornamental treesthat have showy bark; nurseriesintentionally grow them this way.

columnar: Branches are closelyarranged on the stem creating a narrow,vertical habit. Narrower growth thanfastigiate.

conical: Geometric cone-shape(like an upside-down ice cream cone),common in evergreens.

creeping or trail ing:Branches and foliage lay close to theground or trail over walls or boulders;common in groundcovers.

dense: More compact form thantypical; branches and foliage are closetogether, unable to see through.

dwarf: Miniature form,much smallerthan usual; common in conifers.

erect: Upright, with tall, straightstems; can also refer to columnar orfastigiate forms. Usually used todescribe shrubs.

fast ig iate: Narrow, uprightbranching with closely arrangedbranches. Growth is less tight thancolumnar.

horizontal : Branches are parallelto the ground, creating a wide-spreading, flat-topped look.

irregular: No distinct shape, butform can be picturesque.

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different plant forms


mounded: Low, rounded form,close to ground.

open: Branches are far enough apartto allow air and light through—you cansee through it.

oval: Egg-shaped; lower and upperportions of plant are narrower than themiddle.

pyramidal: Somewhat triangularin outline. Base is widest part andnarrows at top; formal looking.

rounded or globular:Curved outline; top of plant resemblesthe upper half of a circle, common intrees.

spreading: Branches spreadupward and outward; common in treesor larger shrubs.

suckering: Multiple stemsoriginate below ground from the roots,resulting in new shoots, common inshrubs.

upright: Branches tend to goupwards and are often rigid.

vase-shaped: Upper part of atree canopy or shrub outline is shapedlike a V.

weeping: Stems of a tree or shrubgracefully arch or bend over toward theground.Often grafted.

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In terms of overall ornamental impact,it’s generally considered best tochoose plants with year-round interest.

While a plant’s flowers are often the mainreason why people select a particularplant, also look at features that will bepresent at other times of the year.

FlowersThe time, duration, color, fragrance, andshowiness of flowers are importantaesthetic features.Most woody plantsflower in the spring, a few species flower inthe summer, and even fewer flower in theautumn or winter.You can produce awonderful effect in the landscape whenyou choose a variety of plants withdifferent flowering times, so thatsomething is nearly always in bloom.Manyflowers bloom in spring, but summersweetclethra, hydrangeas, and clematis arespecies that flower in summer.Many shrubroses and common witchhazel flower intoautumn.

The duration ofbloom variesdramaticallywith each plant.Nevertheless,most flowersonly last one totwo weeks andfor the rest ofthe year, wemust dependon otherornamentalfeatures such asfruit, leaves, fallcolor, or barkand branching,which are visuallyappealing for much longer periods. Someshrubs have longer-lasting flowers such asshrub roses, butterfly bush, potentilla,Japanese spirea, and panicle hydrangea.Remember, flower displays can be cutshort if there is a frost, drought, excessivelywarm temperatures, high winds, or heavyrains.

It is also a great idea to place plants withfragrant flowers near entranceways andwindows. Some in this category includeshrub roses, lilacs,magnolias, and theautumn blooming vine, sweet autumnclematis. Fragrance is related totemperature and humidity; hightemperatures and humidity increasefragrance while cooler temperatures orrain affect it negatively.

The primary consideration with flowers is:Are they large and showy or small, andbest seen up close? Do they really make animpact in the landscape? Maybe individualflowers are not particularly showy butwhen many are produced or occur inclusters before the leaves emerge, theimpact is significant.What color are theflowers? Most are white, pink, or mauve,with yellow and orange being uncommonflower colors in temperate woody plants.Plants with yellow flowers includeforsythias, corneliancherry dogwood, andButterflies magnolia.Make sure the flowercolor does not clash with the building orhouse color or with another plant in bloomat the same time.

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Flowering plants


Fragrant

Clematis terniflora Sweet autumn clematis

Magnolia spp. Magnolias


Syringa spp. Lilacs

Tilia spp. Lindens

Viburnum carlesii Koreanspice viburnum

Long-lasting

Buddleja davidii Butterfly bush

Hamamelis virginiana Common witchhazel

Hydrangea paniculata Panicle hydrangea

Potentilla fruticosa Potentilla


Spiraea japonica Japanese spirea

Ornamental considerations

Does the plant have showyflowers and fruit??

leonard messel magnolia

unique paniclehydrangea


FruitFruit often last longer than flowers and area particularly important ornamentalconsideration. Fruiting mostly occurs inlate summer to autumn.The ornamentalcharacteristics of fruit can be positive ornegative and are influenced by numerousfactors. Some fruits are quite unsightly andcreate a tremendous litter problem; forexample, black walnut, female thornlesshoneylocust, and Hopa crabapple. Others,such as female ginkgo trees, have a veryfoul odor.The brightly colored fruit ofsome ornamental crabapples such as RedJewel®, Harvest Gold®, and Firebird® areimportant for winter interest, but it is bestto find varieties, such as the ones listed,with small, persistent fruit that won’t makea mess on sidewalks.With many plants, thefruit is a positive ornamental feature andfactors such as color, showiness, andattraction for wildlife should also beconsidered.

Many people enjoy watching wildlife thatfeeds on fruit. Plants with fleshy fruit thatattract wildlife include crabapples,hawthorns, serviceberry, and mostviburnums. Dry nut fruit can also attractbirds and other mammals. Species thatproduce nut fruit are usually large treessuch as oaks, beeches, and hickories.Thereare also a few shrubs that produce nut fruitsuch as hazelnuts. However, fruitsometimes attracts unwanted visitors, suchas deer, that not only feed on the availablefruit but on other plants as well—defoliating, damaging, or destroying them.For more information on deer-resistantplants, see the UW-Extension publicationPlants Not Favored by Deer (A3727).

How visible are the fruit? Red is one of thebest colors to draw attention because itattracts not only people but also birdslooking for food. Other colors that occur infruit are white, yellow, orange, blue, black,purple, pink, and bicolor. Are fruit bornesingly or in clusters, which tend to beshowier? Does the foliage hide the fruit?Does it drop early? Some shrubs haveoutstanding displays of fruit such as redand black chokeberries, some viburnums,winterberry, and the vine, Americanbittersweet.

The edibility of fruit is an importantconsideration when choosing plants forpublic areas. Poisonous plants, such ashorsechestnuts and buckeyes, snowberry,burningbush, and the vine, Americanbittersweet, are not appropriate forplaygrounds or places with children closeby, while plants that produce edible fruitsuch as serviceberry, corneliancherrydogwood, and hazelnuts make wonderfuladditions to your yard.

A final consideration regarding fruit is theplant’s pollination requirements.You mayneed pollination by another cultivar of thesame species to get good fruit set, as is thecase with viburnums.Or the plant may bedioecious,meaning it has separate maleand female flowers located on twodifferent plants. Dioecious plants require amale and female plant located close toeach other to produce fruit. Examplesinclude winterberry, and northernbayberry.You maynot want to grow thefemale fruit of aparticular dioeciousspecies due to itssmell or litter mess.Planting a malecultivar canovercome theseproblems. Ginkgo,

thornless honeylocust, and Kentuckycoffeetree female trees produce messyfruit, while the cultivars Autumn Gold,

Skycole (Skyline®),and Espresso arefruitless,malecultivars of ginkgo,thornlesshoneylocust, andKentucky coffeetree,respectively.

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Selecting for fruit


Showy

Aronia spp. Chokeberries

Celastrus scandens American bittersweet

Ilex verticillata Winterberry

Viburnum spp. Viburnums (some)

Attractive to wildlife

Amelanchier spp. Serviceberries

Carya spp. Hickories

Corylus spp. Hazelnuts

Crataegus spp. Hawthorns

Fagus spp. Beeches

Malus spp. Flowering crabapples

Quercus spp. Oaks

Viburnum spp. Viburnums (some)

Edible

Amelanchier spp. Serviceberries

Cornus mas Corneliancherrydogwood

Corylus spp. Hazelnuts

Poisonous

Aesculus spp. Horsechestnutsand buckeyes

Celastrus scandens American bittersweet

Euonymus alatus Burningbush

Symphoricarpos albus Snowberry

Taxus spp. Yews

serviceberry

oak


FoliageThe foliage of ornamental plants exhibitsmany characteristics to consider whenmaking choices for a landscape.Mostleaves are green, but there are differentshades such as blue-green, or forest green.As leaves emerge, they may be a differentcolor than the mature leaves. Some plantshave purple leaves throughout thegrowing season and include Black Lace™

elderberry, Crimson King and Royal RedNorway maples, and Diabolo® and SummerWine® eastern ninebark. A few species such

as Carol MackieDaphne,variegatedTatarian dogwood,and Japanesedappled willowhave variegatedleaves; that is,leaves with twodifferent colorssuch as white and green or yellow andgreen.Variegated leaves provide a nicesplash of color and serve as a focal point inthe landscape.

Don’t forget evergreens—they are not justgreen. Some evergreens, such as Rainbow’sEnd dwarf spruce, produce yellow newgrowth in spring before they turn green.Some evergreens stay yellow throughoutthe year, such as Golden Mop threadleaffalsecypress and Gold Coast® juniper.Others have blue needles all year, such asconcolor or white fir, or blue spruce. Stillothers have a mixture of blue and greenneedles such as Swiss stone pine orSander’s Blue dwarf spruce.

What is the texture of the foliage? Coarse-textured, large foliage on trees allows littlelight to penetrate, which inhibits turfgrowth underneath. Fine-textured foliage(smaller or lacy leaves) on trees allows forfiltered light shade.Thornless honeylocust,Kentucky coffeetree, and katsuratreeprovide filtered shade, allowing turfgrassto grow better than if grown under treeswith dense shade. Foliage may also beglossy, dull, smooth, fuzzy, prickly, rough,wrinkled, or feathery. Contrast between thefoliage and the flowers, fruit, bark, or stemsis often one of a plant’s best features.

Foliage, like some flowers,may bearomatic, especially when rubbed orpruned. Everyone is familiar with fragrant,culinary herbs, such as rosemary, basil, orthyme, but there are some woody plantswith aromatic foliage such as Russian-sage,northern bayberry, arborvitae or easternwhite-cedar or fir.You may only need tobrush against these shrubs to notice theiraroma, and they are particularly effectivewhen planted near walkways, decks, orpatios.

What about fall color? Fall color is animportant consideration given itsspectacular contribution to the landscape.Some plants have poor or nonexistent fallcolor (yellowish-brown), while others arevibrant yellow, orange, red, or purple.Treeswith outstanding fall color include AutumnBlaze® Freeman maple, sugar maple,ginkgo, and apple serviceberry.There aremany different shrubs with excellent fallcolor including red chokeberry, fothergillas,and sumacs.Virginia creeper and Bostonivy are vines with spectacular fall color. Formore information on plants with showy fallcolor, see UW-Extension publicationSelectingWoody Landscape Plants for FallColor: An Illustrated Guide (A3837).

plants with interest ingfoliage


Yellow to gold

Chamaecyparis pisifera Golden Mop threadleaf‘Golden Mop’ falsecypress

Juniperus x pfitzeriana Gold Coast® juniper‘Aurea Improved’

Picea glauca Rainbow’s End‘Rainbow’s End’ dwarf spruce

Thuja occidentalis Sunkist,Yellow Ribbon‘Sunkist’, ‘Yellow Ribbon’ arborvitae

Blue

Abies concolor Concolor, white fir

Picea glauca Sander’s Blue‘Sander’s Blue’ dwarf spruce

Purple

Acer platanoides ‘Crimson Crimson King, RoyalKing’, ‘Royal Red’ Red Norway maples

Physocarpus opulifolius Diabolo®, SummerWine®

‘Monlo’, ‘Seward’ eastern ninebark

Sambucus nigra ‘Eva’ Black Lace™ elderberry

Variegated

Cornus alba Variegated Tatarian‘Argenteo-marginata’ dogwood

Daphne x burkwoodii Carol Mackie Daphne‘Carol Mackie’

Salix integra Japanese dappled‘Hakuro Nishiki’ willow

Is the foliage colorful duringthe growing season or in autumn??

— 12 —

sugar maple

sander ’sblue dwarf

spruce


Bark and branchingMany plants have interesting, ornamentalbark.The textures and colors contributeconsiderable visual appeal and, in someplants, are the primary attraction.Deciduous plants are devoid of leaves for5–6 months during the dormant season, sofeatures such as the bark and branches areparticularly important for creating winterinterest.Trees with very showy barkinclude three-flowered maple, paper birch,and Amur chokecherry.

Branches can also be ornamental, offeringvaried colors and textures. Shrubs thathave colorful twigs, especially in winter,include cultivars of red- and yellow-twigdogwoods, coral bark willow, and the vine,climbing hydrangea. Some plants’ twigcolor is not colorful, but their uniquewinged or twisted branching providesinterest in winter. Some plants in thiscategory include burningbush or wingedeuonymus, Harry Lauder’s walkingstick,and curly willow.

A few shrubs and trees have thorns, spines,or prickles that act as a barrier, preventingunwanted visitors from getting in or out ofthe landscape. Examples include Japanesebarberry, shrub roses, flowering quince,and hawthorns. Use caution when plantingthese species near entranceways, patios, ordecks where sharp projections may injurepeople as they pass by.

Plants with interest ingbark or branches


Showy bark

Acer triflorum Three-flowered maple

Betula papyrifera Paper birch

Crataegus viridis Winter King hawthorn‘Winter King’

Prunus maackii Amur chokecherry

Colorful twigs

Cornus stolonifera Redtwig andyellowtwig dogwoods

Hydrangea petiolaris Climbing hydrangea(vine)

Salix alba ‘Britzensis’ Coral bark willow

Unique branching pattern

Euonymus alatus Burningbush,winged euonymus

Corylus avellana Harry Lauder’s‘Contorta’ walkingstick

Salix matsudana Curly willow‘Tortuosa’

plants with excellentfall color


Acer x freemanii Autumn Blaze®

‘Jeffersred’ Freeman maple

Acer saccharum Sugar maple

Amelanchier x grandiflora Apple serviceberry

Aronia arbutifolia Red chokeberry

Fothergilla spp. Fothergillas

Ginkgo biloba Ginkgo

Hamamelis virginiana Common witchhazel

Nyssa sylvatica Black gum, tupelo

Rhus spp. Sumacs

Does the plant have interest ingbark or branches??

— 13 —

winter kinghawthorn


Soil,moisture, sunlight, wind, pestsusceptibility, air pollution,deicing salt and urban tolerance,

maintenance considerations, and blackwalnut toxicity are all critically importantbut often overlooked during plantselection. If cultural conditions are lessthan optimum for a particular species, it isbest to select either another site or speciesbetter suited to that specific location.Matching your plant choices to theircultural requirements helps to ensure theplant has the best chance for healthygrowth, development, and long-termsurvival.

SoilSoil adaptability factors to consider includetexture, structure and compaction, pH andfertility, and temperature. Choose plantsthat are tolerant, especially to your soiltexture and pH. A soil test taken beforeyou choose your plants will determineyour soil texture, pH, and fertility levels andhelp in making appropriate plantselections.

Soil texture is the percentage ofsand, silt, and clay in a soil. Soil texture isvery difficult to change. Soil textureinfluences soil fertility, drainage, andaeration of soils. In general, a heavy claysoil has poor aeration and drainage, butcan be high in fertility. Sandy soiltypically has good aeration and drainage,but poor structure, fertility, and waterretention. Loamy soil, which has abalanced blend of sand, silt, and clay, hasgood structure, fertility, aeration,drainage, and water retention.Unfortunately, this situation rarely occursin urban and suburban soils.

Do not attempt to improve a heavy claysoil by adding sand; the result will be“cement.” Instead, add organic material,such as sphagnum peat, leaf compost, pinebark, or other organic compost.Manyplants tolerate some amount of clay in thesoil, but there are few plant choices for dry,sandy soils. Some species that can adapt tothese conditions are northern bayberry,common hackberry, shagbark hickory,creeping juniper, black oak, red pine,rugosa rose, and yucca.

Soil structure andcompaction is a great concern inlandscape plantings, particularly in urbanand suburban environments. Soil structurerefers to the soil’s ability to formaggregates (solid particles) of differentsizes, both large and small. Theseaggregates form under natural conditionsover long periods of time. Disturbing ormanipulating the soil reduces or evendestroys the soil’s structure. Construction isa common cause of soil destruction whentopsoil is removed and compacted, leavinghigh-clay subsoil behind. Compaction mayalso be caused by excessive foot and cartraffic.

Loss of soil structure, caused bycompaction, reduces water infiltration anddrainage, decreases aeration levelsrequired for root growth, and makes itmore difficult for roots to penetrate theground. Poor aeration and drainage in soilsis evident where there is standing water,slow drainage, and a hard soil surface thatresembles baked clay. Soil compaction is amajor cause of tree decline, poor growth,and eventual plant death in urban andsuburban areas.

In urban conditions, it is vitally importantto choose plants that tolerate compactedsoils, or to improve the soil structure. If thesoil is heavily compacted and/or poorlydrained (standing water for more than anhour following rainfall), consider improvingdrainage before planting by adding looseorganic matter (peat moss, composted leafmulch, pine bark, or compost) to raise theplanting area.This helps roots becomeestablished in well-oxygenated soils.

Rototillers can be used to loosen up thesoil prior to planting, but do not rototill soildirectly under established trees; doing sowill cut the roots into pieces and lead totree decline. Do not apply topsoil ororganic matter directly into the plantingarea, as this will create an interfacebetween the poorly drained soil and thewell-drained material you added, creatinga “bathtub”effect where water stays in thehole and does not drain out into theexisting soil. There are some plants thatcan tolerate heavily compacted soils suchas common hackberry, hybrid elms,Kentucky coffeetree, and gray dogwood.

— 14 —

Plants for dry,sandy soils


Carya ovata Shagbark hickory

Celtis occidentalis Common hackberry

Juniperus horizontalis Creeping juniper

Juniperus virginiana Eastern red-cedar

Morella (formerly Myrica) Northern bayberrypensylvanica

Pinus resinosa Red pine

Quercus velutina Black oak

Rosa rugosa Rugosa rose

Yucca spp. Yuccas

Cultural considerations

What cultural requirementsdoes it need??

chlorosis onpin oak


Soil pH and fertility are alsoimportant considerations when choosinglandscape plants.The pH of a soil is basedon a range of 0 (very acidic) to 14 (veryalkaline) with a neutral pH of 7.0.Mostwoody plants prefer slightly acidic soil witha pH of 5.5–6.5.You can increase the pH byaddition of lime, though this is rarelyneeded in urban or suburban areas insouthernWisconsin.You can lower the pHby adding elemental sulfur and organicmatter, but this is a slow process, as naturalbacteria will need to convert this insolublesulphur to a form plants can use.

Nutrient availability is often directly relatedto soil pH. Species such as pin oak, redmaple, river birch, and rugosa rose becomevery chlorotic in southeasternWisconsinbecause the pH is too high (alkaline) andiron, or manganese in the case of redmaple, is unavailable for root uptake.Chlorosis symptoms occur on leaves whenthe plants are grown at high pH andmanifest themselves with yellowing leaveswith the main veins in the leaf remainingdark green. Choose plants that are tolerantto high pH soils if your soil is alkaline. Formore information on chlorosis and how tolower your soil pH, see the UW-Extensionpublication Oak and Other Trees Disorder:Chlorosis (A2638).

Some species, such as rhododendrons andazaleas, not only require a slightly acidic toacidic pH, but also fertile soils that are highin organic matter and nutrients. Soilfertility can be improved by addingorganic matter such as compost or leafmold, or by using slow or quick-releasefertilizers. A good rule of thumb is thatbefore you plant anything,make sure youget a soil test to determine pH andnutrient levels.You may already havesufficient phosphorus and potassium inyour soil and addition of more will not bebeneficial to plants.

Soil temperature influences rootgrowth and the rate of chemical andbiological processes.Temperatureextremes can dry out and freeze roots. Inpaved or restricted rooting areas or areassurrounded by concrete or pavement(parking lots, sidewalk cutouts, andcontainers), soil temperatures may becolder in the winter and warmer in thesummer than those in nearby lawn areas.Adding mulch to the top of the plantingarea will help cool soils in summer, insulateroots in winter, and retain moisturethroughout the year. Apply mulch 2–4inches deep and avoid mulch touching thetrunk or branches.With regard tocontainers, they must have drainage andbe large enough to accommodate the rootsystem and insulated to help the plantsurvive cold winters. Roots die atsignificantly warmer temperatures thanthe tops of plants.

MoistureSoil moisture conditions are stronglyinfluenced by the previous factors of soiltexture, structure, temperature, and otherssuch as precipitation patterns and soilinterfaces.Most woody plants need about1 inch of water a week and will needsupplemental irrigation when sufficientrainfall does not occur. Low soil moistureoften occurs in sandy soils, during drought,where there are high soil surfacetemperatures, or when there is highdeicing salt content in the soil. If your soilmoisture characteristics are poor (too wetor too dry) and cannot be improved, besure to choose plants that tolerate thoseconditions.

In general, plants like moist, well-drainedsoils, but some are drought-tolerant and afew tolerate wet soils. Some plants that aredrought-tolerant (once established)include bur oak, junipers, cotoneasters, andgray dogwood.Willows, baldcypress,swamp white oak, and red- or yellow-twigdogwoods are some of the plants thattolerate wet soils.Many of the plants thattolerate wet soil also tolerate poorlydrained, compacted soils.

Other considerations include how muchrainfall the site typically receives.When arethe dry months and do they occur duringthe growing season? If so, a lack of rainfallwill significantly affect plant growth anddevelopment of leaves, flowers, and fruit.Excessive rain can flood areas, decreasingavailable soil oxygen—a requirement forall plants. During winter, snow and ice canweigh branches down and cause limbs tobreak.These are serious factors to considerwhen choosing landscape plants.

SunlightSince plants require sunlight for growth,exposure to the sun is a basicenvironmental consideration whenselecting plants.Most plants prefer full sunto light shade for proper growth andflowering while some tolerate dense shadeand are often found as understory plantsin woodlands. Plants requiring full sunconditions will need at least 6 hours ofdirect sunlight per day; partial shadetolerant plants require 2–5 hours of directsunlight per day, particularly in themornings, whereas shade-loving plantsneed less than 2 hours of direct sunlighteach day, filtered sunlight, or no direct sun.Some plants that tolerate partial to fullshade include Annabelle hydrangea, CarolMackie daphne,witchhazels, yews, andeastern hemlock.

— 15 —

Plants that toleratemoisture extremes


Tolerates dry soils (once established)

Cornus racemosa Gray dogwood

Cotoneaster spp. Cotoneasters

Juniperus spp. Junipers

Quercus macrocarpa Bur oak

Tolerates wet soils

Cornus stolonifera Redtwig andyellowtwig dogwoods

Quercus bicolor Swamp white oak

Salix spp. Willows



Consider the duration and directness ofsunlight. Do buildings or other trees shadethe site? The type of shade in a landscapecan change over time, becoming denser astrees and shrubs mature and fill in spaces.Light patterns can also change with theseasons and can affect growth patterns. Anarea that is in full sun in summer when thesun is high in the sky may have partialshade in spring and fall when the sun is ata lower angle.Visiting the site at differenttimes of the day and season will help youdetermine the light patterns and choose aspecies appropriate to those conditions.

WindConstant winds increase a plant’s need forwater because of greater transpiration andevaporation. Buildings in urban areas cancreate a wind-tunnel effect and increasethe wind speed in those locations. Sitesexposed to strong western orsouthwestern winds should not only haveadequate soil volume and moisture, butalso contain plants suited to thisenvironment that are not prone to winterburn injury. Excessive winter sun and windcan burn broad-leaved and narrow-leavedevergreens—in particular rhododendrons,yews, and eastern hemlock.

Avoid usingstructurallyweak treespecies likewillows,poplars, andsilver maple,that are proneto stormdamage.These species can cause significantdamage during storms if planted nearhomes or other structures. Use trees thathave strong wood and branchattachments with wide crotch angles (theangle distance between the branch andthe main trunk of the tree) such as oaksand hickories. A planting area that is largeenough will be needed to support astrong, extensive root system.

Pest susceptibilityWhether or not a plant is pest-prone orpest-resistant is important. Some species,such as shrub roses, flowering crabapples,and hybrid elms, have disease-resistantvarieties or cultivars that should be usedinstead of the disease-prone types.Muchof the damage caused by insects anddiseases is only cosmetic or non-lifethreatening. However, repeated defoliationor damage over the course of several yearsweakens a plant,making it moresusceptible to severe attack by anotherpest or pathogen and may lead to theplant’s death.

Both native and exotic species aresusceptible to insects and diseases. Chooseplants that are either resistant or notsusceptible to various insects and/orpathogens. Avoid planting evergreenssuch as Colorado blue spruce, Austrian andScots pines, and Rocky Mountain juniper,as they are all highly susceptible to insectsand diseases.

Air pollutionAir quality is an important factor for asensitive plant’s growth and survival. Plantsare subject to site, size, and traffic patterns(for example, exhaust fumes) of urbanareas and local industries, such as powerplants. In addition, plants are affected bythe area’s climate, wind and weatherpatterns. Are large hills nearby? Areasdirectly east of hills or valleys between hillscan lead to inversion layers and trappingof polluted air and smog levels that aredangerous not only to humans, but also toplants. Air pollution can damage planttissues and reduce photosynthesis. Somespecies tolerate specific pollutants betterthan others.

A few plants sensitive to air pollutioninclude sugar and red maples,mountainash, pagoda dogwood, Americanlinden or basswood, eastern white pine,and Norway spruce.These plants typicallyperform better in rural or suburbancommunities with good air circulation, butthey perform poorly in downtown, highlyurbanized areas.

Shade-loving plants


Daphne x burkwoodii Carol Mackie daphne‘Carol Mackie’

Hamamelis spp. Witchhazels

Hydrangea arborescens Annabelle hydrangea‘Annabelle’

Taxus spp. Yews


Is the plant sensit ive to airpollution or deic ing salts??

— 16 —

annabellehydrangea

fire bl ighton crabapple


Salt toleranceTolerance to road deicing salt, especially tosodium chloride (NaCl), is very importantfor plants near streets or sidewalks that areheavily salted in winter. Salt damage maybe incurred from aerial salt spray, which iscommon near roads with fast movingtraffic. This salt is deposited on foliage andcan cause significant damage to buds andleaves.

Salt may also accumulate in the soil assnow melts, especially near roads orsidewalks. Excessive soil salt can have amajor effect on a plant’s water andnutrient uptake. Some plants tolerant todeicing salts include Kentucky coffeetree,Japanese tree lilac, chokeberries, andsumacs. For more information on saltinjury and plants tolerant to deicing salts,see the UW-Extension publication DeicingSalt Injury in the Landscape and Salt-Tolerant Landscape Plants (A3869).

Urban toleranceUrban tolerance refers to a plant’stolerance to the cultural considerationsdiscussed above. Plants that tolerate anurban environment have the ability towithstand harsh conditions such asextremes in temperature (both air andsoil), extremes in moisture levels (both wetand dry), soil compaction, poor drainageand aeration, pH extremes, low fertility,deicing salts, air pollution, high winds fromair tunnels created between buildings, andrestricted areas to develop roots andshoots due to overhead and/orunderground utilities. All these factors cansignificantly stress plants and increasetheir susceptibility to insects and diseases.Urban tolerance varies from plant to plant,but it can be enhanced with propercultural practices, soil amendment, andspecies selection. Choose plants that areknown to tolerate urban conditions if youlive in a highly urbanized area. Some nativespecies are appropriate for these extremes,while others are not. Urban soils areanything but native.

MaintenanceconsiderationsTrees and shrubs require propermaintenance and pruning, especially in thefirst 5–10 years.This will allow properheight, spacing, and clearance of largerbranches that grow over sidewalks orstreets.You will need to water often(especially during hot, dry weather) untilthe plant is established which may take upto 3 years. In general, slower growing treesand shrubs require less pruning and tendto live longer with fewer structuralproblems.

Be sure to consider the longevity of plantsyou may select. Some popular plants, suchas white-barked birches, purpleleafsandcherry, Newport plum, and Coloradoblue spruce, are short-lived in the urbanlandscape.You may choose to plant aparticular tree or shrub, but if it is pest- anddisease-prone, it may die in a few yearsfrom infestation or infection. Somemunicipalities may prohibit planting ofcertain plant species that are known to bea litter nuisance, hazard to people,encourage insects, or harbor diseases.Check with your city or municipality forinformation. Proper site and plant selectioncan reduce costs due to maintenance,removal, infrastructure damage, andliability.

Black walnut toxicityBlack walnut and butternut trees and, to amuch lesser extent hickories, produce atoxin called juglone in all parts of the tree,but especially in the buds, nut hulls, androots.This toxin prevents many otherplants from growing under or near thesetrees. Plants susceptible to juglone will bestunted and can wilt and/or die.Theseinclude tomatoes, potatoes, eggplant,peppers, and ornamentals such as lilacs,rhododendrons and azaleas, floweringcrabapples, and peonies.The toxic effectsof a mature black walnut tree can extendfar away from the tree trunk, with thegreatest toxicity occurring within the tree’sdrip line.

If you must plant in the vicinity of a blackwalnut, it is essential to choose plants thatare resistant. Even after a black walnut treeis removed, juglone will not be eliminatedbecause the toxin is in the tree’s roots. Itwill take many years for the roots to decayand toxin levels to diminish. Do not usewood chips or bark pieces from a walnuttree as mulch. For more information onblack walnut toxicity and plants tolerant orsusceptible to juglone see BlackWalnutToxicity (XHT1017,www.uwex.edu/ces/wihort/GardenFacts.html).

— 17 —

What type of landscape maintenanceam I will ing to provide? ?

Are there any regulat ions or localordinances preventing me from planting??

black walnut


Native or exoticA selection factor that you may wish toconsider is the native origin of a potentialplant choice. Is a particular species nativeto your area? Planting exclusively nativespecies in the landscape can be beautifulin a home garden, but in harsh urbanconditions,many native plants perish dueto poor soils, drainage problems, deicingsalts, drought, and heat.Many exoticspecies can be used in most residentiallandscapes, and very few of them are trulyinvasive. Some are considerably moretolerant to urban conditions compared tonative plants.

InvasivenessExotic species have brought with them theissue of ecological invasiveness. Howinvasive in the wild is this species? Avoidexotic species that are very invasive suchas autumn-olive, black locust, buckthorns(common and tallhedge glossy),honeysuckles (Amur, Bell’s, Morrow’s,Tatarian, Freedom, and Honeyrose),multiflora rose, Oriental bittersweet,Russian-olive, Siberian elm, and whitemulberry.These plants can take overforested areas, replacing native speciesand causing ecological damage. Evensome native species could be consideredaggressive because they reseed readily

and/or spread quickly, such asboxelder and gray dogwood,the latter if it is growing inprairies.

Avoid planting potentiallyinvasive species such as Amurmaple, burningbush, Englishivy, European cranberrybushviburnum, Japanese barberry,Norway maple, vinca, andwintercreeper euonymus nearnatural or wooded areas.Thesespecies can readily spread inthe wild through reseedingand/or suckering growth.

— 18 —

What exist ing vegetat ion exists in the area?Are there any invasive plants??Native habitat and invasiveness

tallhedgeglossy buckthorn( invasive)

invasive buckthornin forest understory

nativepaper birch


When selecting nurseryplants,make sure you payparticular attention to the

factors below. Avoid buying stock thatlooks questionable, even though it may becheap. By properly selecting qualitynursery stock in the beginning, you willhave a head start on establishing a healthylandscape. Buy landscape plants from anursery or garden center with a goodreputation and people you trust. Chancesare that an experienced, reputable nurseryor garden center will have grown andmaintained the plants properly and theplants will reliably establish in your gardenif they are planted and maintainedcorrectly.

FoliageA healthy, well-balanced crown should bevisible. Foliage should be free of insectsand diseases and turgid (not wilting).Theleaves should be a healthy green colorunless you are working with a yellow, blue,purple, or variegated-leaf cultivar. Avoidplants with scorched or brown leafmargins; this indicates water stress.

Trunk, bark, andbranchesFor trees, a straight, single, central leader ispreferred, unless the plant is normally soldas a multi-stem or clump form tree.Thetrunk should be free of insect holes,damage, cracks, and sunken or swollenareas. It should have good taper and flareappropriately at the base.The branchesshould be evenly distributed in the crownpreferably with a wide angle ofattachment between the trunk and thebranch.The branches should show goodvigor and growth. Avoid buying trees withlots of suckers (shoots) at the base orwatersprouts in the crown (shoots that donot bear flowers or fruit and are growingstraight up and not outward). Underneath,the top layer of bark on the branchesshould be green. Brittle branches thatbreak off easily are a sign of a dead ordying tree or shrub.

RootsRoots are the most important part of aplant, but they are often overlooked.Examine the root system, if possible, on acontainer-grown plant before youpurchase it. Plants should be well-rootedand firmly established in the container.Healthy, white, fibrous roots with evenlydistributed lateral roots should beapparent. Avoid buying trees or shrubswith circling or matted roots. Circling rootsin a container will need to be cut orstretched out before planting in the soil toprevent future girdling roots (roots thatencircle the trunk and kill the plant).

If buying a balled and burlapped tree,make sure the trunk is centered in the rootball and firmly attached without a loose ordamaged root ball. All plants should have aroot ball that is adequate for the size of thecrown or caliper of the trunk as specifiedby the American Standard for NurseryStock. A reputable nursery will have thisinformation.The root ball should be moistat time of purchase and not dry. Avoidplants with weedy root balls, as you willhave to remove the weeds before plantingto avoid introducing them into your yard.Balled and burlapped root balls should becovered with natural burlap, not synthetic.

If purchasing bare-root stock,make surethe roots have been kept moist withpacking material or burlap, are adequatelyspaced around the plant, and have nocircling or kinked roots.

— 19 —

Selecting high-quality nursery stock

How do I know if I am purchasinghigh-qual ity nursery stock? ?

balled andburlapped trees


ReferencesDirr, M.A. 1997.Dirr’s Hardy Trees and

Shrubs: An Illustrated Encyclopedia.Timber Press, Portland, OR.

Rose, N., D. Selinger, and J.Whitman. 2001.Growing Shrubs and Small Trees in ColdClimates, Contemporary Books,Lincolnwood, IL.

For moreinformationTo learn more about gardening inWisconsin based on the latest universityresearch, visit the web sites of theUW–Madison Horticulture Team(www.uwex.edu/ces/wihort/) andUW–Extension Publications(learningstore.uwex.edu).

The following publications are availablefrom UW–Extension Publications:

Guide to Selecting Landscape Plants forWisconsin (A2865). Describes the matureheight, shape, and preferred growingconditions for hundreds of trees, shrubs,and vines.

Plants Not Favored by Deer (A3727). Alengthy list of plants deer tend to avoid.

SelectingWoody Landscape Plants for FallColor: An Illustrated Guide (A3837).Brighten your autumn by includingplants with stunning fall color in yourlandscape.

Deicing Salt Injury in the Landscape andSalt-Tolerant Landscape Plants (A3869).Identify and prevent salt injury. Includesan extensive list of salt-tolerant plants.

— 20 —

Arborvitae . . . . . . . . . . . . . . . . . . . . . . . . . . . Thuja occidentalisArborvitae ‘Sunkist’ . . . . . . . . . . . . . . . . . . . Thuja occidentalis ‘Sunkist’Arborvitae ‘Yellow Ribbon’ . . . . . . . . . . . . Thuja occidentalis ‘Yellow Ribbon’Autumn-olive . . . . . . . . . . . . . . . . . . . . . . . . . Elaeagnus umbellataAzaleas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Rhododendron spp.Baldcypress . . . . . . . . . . . . . . . . . . . . . . . . . . . Taxodium distichumBarberry, Japanese . . . . . . . . . . . . . . . . . . . . Berberis thunbergiiBarberry, Japanese, Crimson Pygmy. . . . Berberis thunbergii

‘Crimson Pygmy’Basswood. . . . . . . . . . . . . . . . . . . . . . . . . . . . . Tilia americanaBayberry, Northern . . . . . . . . . . . . . . . . . . . .Morella (formerlyMyrica)

pensylvanicaBeech, American . . . . . . . . . . . . . . . . . . . . . . Fagus grandifoliaBeech, Purple-leaf . . . . . . . . . . . . . . . . . . . . . Fagus sylvatica f. purpureaBirch, Paper . . . . . . . . . . . . . . . . . . . . . . . . . . . Betula papyriferaBirch, River. . . . . . . . . . . . . . . . . . . . . . . . . . . . Betula nigraBirches,White-barked . . . . . . . . . . . . . . . . . Betula papyrifera,

B. populifolia, B. pendulaBittersweet, American . . . . . . . . . . . . . . . . . Celastrus scandensBittersweet, Oriental . . . . . . . . . . . . . . . . . . Celastrus orbiculatusBlack Gum . . . . . . . . . . . . . . . . . . . . . . . . . . . . Nyssa sylvaticaBoxelder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Acer negundoBoxwoods . . . . . . . . . . . . . . . . . . . . . . . . . . . . Buxus spp.Buckeyes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Aesculus spp.Buckthorn, Common . . . . . . . . . . . . . . . . . . Rhamnus catharticusBuckthorn,Tallhedge Glossy . . . . . . . . . . . Rhamnus frangula ‘Columnaris’Burningbush. . . . . . . . . . . . . . . . . . . . . . . . . . Euonymus alatusButterfly Bush. . . . . . . . . . . . . . . . . . . . . . . . . Buddleja davidiiButternut . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Juglans cinereaChokeberry, Black . . . . . . . . . . . . . . . . . . . . . Aronia melanocarpaChokeberry, Red . . . . . . . . . . . . . . . . . . . . . . Aronia arbutifoliaChokecherry, Amur. . . . . . . . . . . . . . . . . . . . Prunus maackiiClematis, Sweet Autumn . . . . . . . . . . . . . . Clematis ternifloraClethra, Summersweet . . . . . . . . . . . . . . . . Clethra alnifoliaCoffeetree, Kentucky . . . . . . . . . . . . . . . . . . Gymnocladus dioicaCotoneasters. . . . . . . . . . . . . . . . . . . . . . . . . . Cotoneaster spp.Crabapples, Flowering. . . . . . . . . . . . . . . . .Malus spp.Crabapple, Cinderella® . . . . . . . . . . . . . . . . .Malus ‘Cinzam’Crabapple, Firebird® . . . . . . . . . . . . . . . . . . . . Malus sargentii ‘Select A’Crabapple, Harvest Gold® . . . . . . . . . . . . . .Malus ‘Hargozam’Crabapple, Hopa . . . . . . . . . . . . . . . . . . . . . .Malus ‘Hopa’Crabapple, Red Jewel® . . . . . . . . . . . . . . . . .Malus ‘Jewelcole’Crabapple,Tina . . . . . . . . . . . . . . . . . . . . . . .Malus sargentii ‘Tina’Creeper,Virginia . . . . . . . . . . . . . . . . . . . . . . Parthenocissus quinquefoliaCurrant, Alpine . . . . . . . . . . . . . . . . . . . . . . . . Ribes alpinumDaphne, Carol Mackie . . . . . . . . . . . . . . . . . Daphne x burkwoodii

‘Carol Mackie’Dogwood, Corneliancherry . . . . . . . . . . . . Cornus masDogwood, Flowering . . . . . . . . . . . . . . . . . . Cornus floridaDogwood, Gray . . . . . . . . . . . . . . . . . . . . . . . Cornus racemosaDogwood, Pagoda . . . . . . . . . . . . . . . . . . . . Cornus alternifoliaDogwood, Redtwig and Yellowtwig . . . . Cornus stoloniferaDogwood,Variegated Tatarian . . . . . . . . . Cornus alba

‘Argenteo-marginata’Douglas-fir. . . . . . . . . . . . . . . . . . . . . . . . . . . . Pseudotsugamenziesii var.glaucaElderberry, Black Lace™ . . . . . . . . . . . . . . . . Sambucus nigra ‘Eva’Elm, Siberian . . . . . . . . . . . . . . . . . . . . . . . . . . Ulmus pumilaEuonymus,Winged. . . . . . . . . . . . . . . . . . . . Euonymus alatusEuonymus,Wintercreeper . . . . . . . . . . . . . Euonymus fortuneiFalsecypress, Threadleaf, Golden Mop . Chamaecyparis pisifera

‘Golden Mop’

Scient if ic names of plants


— 21 —

Fir, Concolor or White . . . . . . . . . . . . . . . . . Abies concolorForsythia, Border . . . . . . . . . . . . . . . . . . . . . . Forsythia x intermediaForsythia, Sunrise . . . . . . . . . . . . . . . . . . . . . Forsythia ‘Sunrise’Fothergillas . . . . . . . . . . . . . . . . . . . . . . . . . . . Fothergilla spp.Ginkgo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ginkgo bilobaHackberry, Common . . . . . . . . . . . . . . . . . . Celtis occidentalisHawthorn,Winter King . . . . . . . . . . . . . . . . Crataegus viridis ‘Winter King’Hazelnuts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Corylus spp.Hemlock, Eastern or Canadian . . . . . . . . . Tsuga canadensisHickory, Shagbark . . . . . . . . . . . . . . . . . . . . Carya ovataHoneylocust, Thornless, Skyline® . . . . . . . Gleditsia triacanthos var.

inermis ‘Skycole’Honeysuckle, Amur . . . . . . . . . . . . . . . . . . . Lonicera maackiiHoneysuckle, Bell’s . . . . . . . . . . . . . . . . . . . . Lonicera x bellaHoneysuckle, Freedom . . . . . . . . . . . . . . . . Lonicera ‘Freedom’Honeysuckle, Honeyrose . . . . . . . . . . . . . . Lonicera ‘Honeyrose’Honeysuckle,Morrow’s . . . . . . . . . . . . . . . . Lonicera morrowiiHoneysuckle, Tatarian . . . . . . . . . . . . . . . . . Lonicera tataricaHornbeam, American . . . . . . . . . . . . . . . . . Carpinus carolinianaHorsechestnuts . . . . . . . . . . . . . . . . . . . . . . . Aesculus spp.Hydrangea, Annabelle. . . . . . . . . . . . . . . . . Hydrangea arborescens

‘Annabelle’Hydrangea, Climbing. . . . . . . . . . . . . . . . . . Hydrangea petiolarisHydrangea, Panicle, Unique. . . . . . . . . . . . Hydrangea paniculata ‘Unique’Ivy, Boston . . . . . . . . . . . . . . . . . . . . . . . . . . . . Parthenocissus tricuspidataIvy, English. . . . . . . . . . . . . . . . . . . . . . . . . . . . Hedera helixJuniper, Creeping . . . . . . . . . . . . . . . . . . . . . Juniperus horizontalisJuniper, Gold Coast® . . . . . . . . . . . . . . . . . . . Juniperus x pfitzeriana

‘Aurea Improved’Juniper, Rocky Mountain . . . . . . . . . . . . . . Juniperus scopulorumJuniper, Saybrook Gold . . . . . . . . . . . . . . . . Juniperus x pfitzeriana

‘Saybrook Gold’Katsuratree . . . . . . . . . . . . . . . . . . . . . . . . . . . Cercidiphyllum japonicumLilac, Japanese Tree . . . . . . . . . . . . . . . . . . . Syringa reticulataLinden, American . . . . . . . . . . . . . . . . . . . . . Tilia americanaLocust, Black . . . . . . . . . . . . . . . . . . . . . . . . . . Robinia pseudoacaciaMagnolia, Butterflies . . . . . . . . . . . . . . . . . .Magnolia ‘Butterflies’Magnolia, Leonard Messel . . . . . . . . . . . . .Magnolia x loebneri

‘Leonard Messel’Maple, Amur . . . . . . . . . . . . . . . . . . . . . . . . . . Acer tataricum subsp. ginnalaMaple, Freeman, Autumn Blaze® . . . . . . . Acer x freemanii ‘Jeffersred’Maple,Miyabe, State Street® . . . . . . . . . . . Acer miyabei ‘Morton’Maple, Norway . . . . . . . . . . . . . . . . . . . . . . . . Acer platanoidesMaple, Norway, Crimson King. . . . . . . . . . Acer platanoides ‘Crimson King’Maple, Norway, Royal Red . . . . . . . . . . . . . Acer platanoides ‘Royal Red’Maple, Red. . . . . . . . . . . . . . . . . . . . . . . . . . . . Acer rubrumMaple, Silver . . . . . . . . . . . . . . . . . . . . . . . . . . Acer saccharinumMaple, Sugar . . . . . . . . . . . . . . . . . . . . . . . . . . Acer saccharumMaple,Three-flowered . . . . . . . . . . . . . . . . Acer triflorumMountainash . . . . . . . . . . . . . . . . . . . . . . . . . Sorbus spp.Mulberry,White . . . . . . . . . . . . . . . . . . . . . . .Morus albaMusclewood . . . . . . . . . . . . . . . . . . . . . . . . . . Carpinus carolinianaNinebark, Eastern, Diabolo® . . . . . . . . . . . . Physocarpus opulifolius ‘Monlo’Ninebark, Eastern, SummerWine® . . . . . Physocarpus opulifolius ‘Seward’Oak, Black. . . . . . . . . . . . . . . . . . . . . . . . . . . . . Quercus velutinaOak, Bur . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Quercus macrocarpaOak, Chinkapin. . . . . . . . . . . . . . . . . . . . . . . . Quercus muehlenbergiiOak, Pin. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Quercus palustrisOak, SwampWhite . . . . . . . . . . . . . . . . . . . . Quercus bicolorPachysandra, Japanese . . . . . . . . . . . . . . . . Pachysandra terminalisPawpaw . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Asimina trilobaPeonies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Paeonia spp.

Pine, Austrian . . . . . . . . . . . . . . . . . . . . . . . . . Pinus nigraPine, EasternWhite. . . . . . . . . . . . . . . . . . . . Pinus strobusPine, Ponderosa . . . . . . . . . . . . . . . . . . . . . . . Pinus ponderosaPine, Red. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pinus resinosaPine, Scots . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pinus sylvestrisPine, Swiss Stone . . . . . . . . . . . . . . . . . . . . . Pinus cembraPhlox, Creeping . . . . . . . . . . . . . . . . . . . . . . . Phlox subulataPlum, Newport . . . . . . . . . . . . . . . . . . . . . . . Prunus ‘Newport’Poplars . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Populus spp.Potentilla . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Potentilla fruticosaQuince, Flowering. . . . . . . . . . . . . . . . . . . . . Chaenomeles speciosaRed-cedar, Eastern . . . . . . . . . . . . . . . . . . . . Juniperus virginianaRedbud, Eastern. . . . . . . . . . . . . . . . . . . . . . . Cercis canadensisRhododendrons . . . . . . . . . . . . . . . . . . . . . . Rhododendron spp.Rose,Multiflora . . . . . . . . . . . . . . . . . . . . . . . Rosa multifloraRose, Rugosa. . . . . . . . . . . . . . . . . . . . . . . . . . Rosa rugosaRose, Shrub . . . . . . . . . . . . . . . . . . . . . . . . . . . Rosa spp.Russian-olive. . . . . . . . . . . . . . . . . . . . . . . . . . Elaeagnus angustifoliaRussian-sage. . . . . . . . . . . . . . . . . . . . . . . . . . Perovskia atriplicifoliaSandcherry, Purpleleaf . . . . . . . . . . . . . . . . Prunus x cistenaSassafras. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Sassafras albidumServiceberry, Apple . . . . . . . . . . . . . . . . . . . Amelanchier x grandifloraSnowberry. . . . . . . . . . . . . . . . . . . . . . . . . . . . Symphoricarpos albusSpirea, Japanese . . . . . . . . . . . . . . . . . . . . . . Spiraea japonicaSpruce, Colorado Blue . . . . . . . . . . . . . . . . Picea pungens var. glaucaSpruce, Norway . . . . . . . . . . . . . . . . . . . . . . . Picea abiesSpruce, Rainbow’s End Dwarf . . . . . . . . . . Picea glauca ‘Rainbow’s End’Spruce, Sander’s Blue Dwarf . . . . . . . . . . . Picea glauca ‘Sander’s Blue’Sumacs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Rhus spp.Tuliptree or Tulip-poplar. . . . . . . . . . . . . . . Liriodendron tulipiferaTupelo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Nyssa sylvaticaViburnum, American Cranberrybush, . . Viburnum trilobumCompact ‘Compactum’

Viburnum, European Cranberrybush. . . Viburnum opulusViburnum, Koreanspice. . . . . . . . . . . . . . . . Viburnum carlesiiVinca . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Vinca minorWalkingstick, Harry Lauder’s . . . . . . . . . . . Corylus avellana ‘Contorta’Walnut, Black . . . . . . . . . . . . . . . . . . . . . . . . . Juglans nigraWhite-cedar, Eastern or Northern . . . . . . Thuja occidentalisWillow, Coral Bark . . . . . . . . . . . . . . . . . . . . . Salix alba ‘Britzensis’Willow, Curly . . . . . . . . . . . . . . . . . . . . . . . . . . Salix matsudana ‘Tortuosa’Willow, Japanese Dappled. . . . . . . . . . . . . Salix integra ‘Hakuro Nishiki’Winterberry. . . . . . . . . . . . . . . . . . . . . . . . . . . Ilex verticillataWisteria, Kentucky . . . . . . . . . . . . . . . . . . . .Wisteria macrostachysWitchhazel, Common . . . . . . . . . . . . . . . . . Hamamelis virginianaWoodruff, Sweet . . . . . . . . . . . . . . . . . . . . . . Galium odoratumYews. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Taxus spp.Yuccas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Yucca spp.


Copyright © 2008 by the Board ofRegents of the University of WisconsinSystem. All rights reserved. Send inquiriesabout copyright permission to ExtensionPublishing, Rm. 231, 432 N. Lake Street,Madison,Wisconsin 53706.

Author: Laura Jull is associate professorof horticulture, College of Agriculturaland Life Sciences, University ofWisconsin–Madison and University ofWisconsin–Extension, CooperativeExtension. Produced by CooperativeExtension Publishing:Meg Gores andLinda Deith, editors; Susan Anderson,designer.

Photo credits: Linda Deith—cover;iStockphoto.com—inside front cover,hydrangeas (p. 16), balled and burlappedtrees (p. 19); Susan Mahr—garden path(p.21); Laura Jull and Ed Hasselkus—all other images.

Reviewers: Jeff Iles, woody plantExtension specialist, Department ofHorticulture, Iowa State University, Ames,Iowa, and Teryl Roper, former fruit cropExtension specialist, Department ofHorticulture, University of Wisconsin–Madison,Madison,Wisconsin.

Issued in furtherance of CooperativeExtension work, Acts of May 8 and June 30,1914, in cooperation with the U.S.Department of Agriculture, University ofWisconsin–Extension, CooperativeExtension.

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