Irrigation of Xeric-Adapted Landscape Plantsirrigationmanagement.nmsu.edu/documents/irrigxeric... · Fallugia paradoxa Apache plume 0.05 Helianthus maximiliani Maximilian sunflower

Irrigation of Xeric-Adapted Landscape Plants

Southwest Turfgrass AssociationRecreational Landscape Conference and Expo

Albuquerque, NM October 27‐29, 2014

Daniel Smeal (CID, CLIA) New Mexico State University Agricultural Science Center at Farmington

Overview

• Xeriscaping – introduction

• Irrigation – turf vs. xeriscape

• Irrigation scheduling – review

• Drip irrigation for xeriscapes

• Irrigation requirement of xeriscape plants

• Xeriscape plants – some examples

Daniel Smeal, College Professor/Irrigation Specialist – NMSU’s ASC Farmington

What is a xeriscape?

• Term derived from Greek word ‘xeros’ meaning dry.

• Water-efficient landscaping that’s appropriate to the natural environment.– Usually consists of native plants or plants native to similar arid

environments


To some, it might be ‘zero’scaping.


To others, it might be a cactus garden

Cactus can be an attractive component of a xeriscape garden.


Most would agree that this is not a SW xeriscape.


Xeriscape Demonstration Garden at NMSU’s ASC -Farmington

Aesthetically pleasing colors, scents, etc.Habitat for humans, wildlifeFunctional: screens, windbreaksProvides food and shelter for wildlife (e.g. birds, butterflies, etc.)


Irrigation Management

Turf vs. Xeriscape


TURF• Single species or type• Uniform water req. over large area• Sprinkler irrigated (DU < 0.70)• Frequent irrigations required (e.g. 3

times/week) with short run times• K = 0.8 (CS Turf); 0.6 (WS Turf)

XERISCAPE• Variety of species • Variable water requirements• Drip irrigated (DU > 0.85)• Low irrigation frequency (e.g. weekly

or more) with longer runtimes• K = ranges from < 0.1 to ~ 0.5

Turf vs. Xeriscape


Irrigation Scheduling

A Review


Effective landscape irrigation scheduling requires:

– An estimate of the plant’s daily water-use or evapotranspiration (ET) for acceptable quality.

– Knowing the output (e.g. precipitation rate) and irrigation efficiency (distribution uniformity or DU) of the irrigation system.

– Knowing the soil’s water characteristics.• Water holding capacity• Intake rate


ET estimation using weather data and an adjustment factor (K). • ET = ET(ref) x K

Where:o ET = estimated evapotranspiration (or water-use) of the plants in

the landscape o ET (ref) = a reference ET calculated from weather datao K = adjustment factor to account for plant species, size, growth

stage, etc. Most smart controllers use this method!


Sources of ET(ref) and K?

• ET(ref) – New Mexico Climate Center website (http://weather.nmsu.edu/), or climate networks in other states

• K values (KL) – various references

• Most cited K values for turf:– Cool season (KBG, TF, PR) – 0.80– Warm season (Bermuda, buffalo, grama) – 0.60 – 0.65


Example: Cool‐Season Turf (e.g. Kentucky bluegrass)

• Location: Los Lunas

• Time of year: Last week in May

• Reference ET obtained from NM Climate Center website: http://weather.nmsu.edu/

• Adjustment factor (Kc) = 0.80 for cool season turf when uniformly green


Reference ET from NMCC


Example: Daily ET estimate for cool‐season turf

• ET = ET(ref) x K

• Avg. daily ET(ref) (in this case ETo) = 0.22 in.

• Adjustment factor (K) = 0.80

• Estimated ET/day = 0.22 x 0.80 = 0.18 inch


Irrigation requirement (IR)• Depends on the efficiency (DU) of the irrigation system and

the effective rainfall or R (60 to 75% of amounts > 0.20 inch) between irrigations.

IR = (ET – R) / DU • Example with measured DU of 0.75 and no rainfall:

IR = (0.18 inch – 0) / 0.75 = 0.28 inch per day

Then, the water to apply per irrigation would be the daily IR x irrigation frequency (days)


Irrigation runtime

• For turf:

Runtime = IR / Precipitation rate (PR) of sprinkler syst.– Example with PR of 0.70 inch per hour and irrigation frequency of

every-other day:0.24 x 2 ÷ 0.70 = 0.69 hour or 41 minutes


• IR for turf is in inches

• To convert to gallons multiply irrigation depth x area irrigated x 0.623 (takes 0.623 gal. to cover 1 sq. ft. to depth of 1 inch)

• Example

0.48 x (30 x 100) x 0.623 = 897 gallons

30 ft

100 ft.


Estimating (IR) for xeriscape plants (individual plant method)

IR = (ETr – R) x K x CA x 0.623 / 0.90 Where:

• IR = irrigation requirement, gallons/plant• ETr = total reference ET between irrigations, inches • R = effective rainfall between irrigations (inches)• K = adjustment factor for the species of plant • CA = canopy area, sq. ft. per plant (0.785 x D2)

where D = canopy diameter (feet)• 0.623 = conversion factor (inches to gallons)• 0.90 = assumed efficiency of drip system


Sources of K values for xeriscape plants:

• Description of xeriscape garden and K values (adjustment factors) for xeric-adapted plants: http://irrigationmanagement.nmsu.edu/documents/2007xericrevproceedingsforia.pdf

• California WUCOLS http://www.water.ca.gov/wateruseefficiency/docs/wucols00.pdf


Some xeriscape plant KL values based on research at ASC garden ‐ Farmington:

Species Common Name KL

Berlandiera lyrata Chocolate flower 0.05Buddleia davidii Butterfly bush 0.45Chilopsis linearis Desert willow 0.05Fallugia paradoxa Apache plume 0.05Helianthus maximiliani Maximilian sunflower 0.30Hesperaloe parviflora Red Yucca 0.15Perovskia atriplicifolia Russian sage 0.15Penstemon ambiguus Sand penstemon 0.10Sporobolis wrightii Sacaton 0.20

Plants with a K value of less than 0.1 may only require irrigation during drought


Xeriscape Demonstration Garden

No Irrigation

40% ETTALL

20% ETTALL

60% ETTALL

80 ft

40 ft


Example:

• Red yucca with canopy diameter of 4 feetCA = D2 x 0.785 = 4 x 4 x 0.785 = 12.6 sq. ft.

• Irrigating once per week

• Week of May 25 – 31 at Los Lunas– Total ETr for week = 1.8 inches (NMCC)– No rain

• K value from table (website) = 0.15


Finding reference ET (example): New Mexico Climate Center (NMCC)

Total for week = 1.8 inches


Some xeriscape plant KL values based on research at ASC garden - Farmington:

Species Common Name KL

Berlandiera lyrata Chocolate flower 0.05

Buddleia davidii Butterfly bush 0.45

Chilopsis linearis Desert willow 0.05

Fallugia paradoxa Apache plume 0.05

Helianthus maximiliani Maximilian sunflower 0.30

Hesperaloe parviflora Red Yucca 0.15

Perovskia atriplicifolia Russian sage 0.15

Penstemon ambiguus Sand penstemon 0.10

Sporobolis wrightii Sacaton 0.20

Plants with a K value of less than 0.1 may only require irrigation during drought


Formula: IR = (ETr – R) x K x CA x 0.623 / 0.90

• IR = (1.8 – 0) x 0.15 x 12.6 x 0.623 / 0.90 =2.4 gallons for the week*

Irrigation runtime with a 1 gph emitter = 2.4 hours = 2 hours and 25 minutes

*This amount agrees with observations from the xeriscape demo garden at the no irrigation and 4 gallon per week irrigation level


Problem• With the variety of plants and irrigation requirements,

how the heck do you irrigate them all efficiently (prevent over-irrigating or under-irrigating) if in a single zone?


Drip Irrigation

For Xeriscapes


Supertif Button PC1 emittersD001 (1) D002 (2) D004 (3.3) D006 (1)

Katif Low Profile PC emittersD043 (3.3) D044 (2) D045 (1)

DIG PC emittersD076 (1) D077 (2) D078 (4)

NC Flag emitters

D021 (1) D022 (2) D023 (4)NC2 Button emitters

D012 (1) D013 (2)

O1G (1)

Orbit NC

O2G (2)D079 (0.5) D080 (1)

Netafim PC

1PC – pressure compensating2NC – non-compensatingNumber in parentheses indicates manufacturer specified FR in gph

Orbit NC Flag

O4G (4)

Point Source Emitters ‐ Examples


Getting water to the plant


Adjustable flow emitter: good for providing variable rates of water as conditions change.

Drip line (¼ inch) with built-in emitters: good for watering evenly around trees or large shrubs

Connectors


Emitter selection

• The ‘base-plant’ method is used to select appropriate emitters so that all plants in the landscape ‘hydrozone’ receive their specific irrigation requirement (IR) within the calculated run-time (RT) for the base plant.

• The base plant is the species requiring the least amount of water in the zone.


Steps for emitter selection in a mixed‐plant xeriscape:

1. Calculate the daily IR of each species in the zone at a given ET based on the K value and canopy area.– This is most easily done by including all required data in a table.


Example: Table set‐up for IR of all plants on zone:

Plant Species

ETr(inch)

K D (feet)

CA (sq ft)

IR, gals

week - - D2 x 0.785 ETr x K x CA x 0.623/0.90 A 1.8 0.10 10 78.5 9.8B 1.8 0.35 2.5 4.9 2.1C 1.8 0.20 4.0 12.6 3.1D 1.8 0.40 4.5 15.9 7.9E 1.8 0.15 6.0 28.3 5.3

Each individual of the same species will normally have about the same IR unless they have different canopy areas due to replanting, etc.


Establishing zone runtime

2. Select the plant with the lowest IR and calculate the runtime (RT) to provide IR using an emitter with a low flow rate (e.g. ½ gph) to maximize RT.

• In the example, plant B is the base plant w/ IR of 2.1 gals.• With a ½ gph emitter, runtime would be 4.2 hours• IR / flow rate = 2.1 / 0.5 = 4.2 or 4 hrs. + 18 mins.


Calculating emitter flow rates for other plants3. Divide the IR of each other species in the zone by the

established runtime (RT) to get a total required flow rate (FR) for each plant (FR = IR / RT).Example – species A w/ IR of 9.8 gals.

FR = 9.8 / 4.2 = 2.3 gph4. Select a reasonable number of emitters for each plant

considering the plant’s canopy area.Note: one guideline suggests 1 emitter per 20 sq ft of canopy area on a sandy loam soil; refer to IA guidelines or Google• Example – plant A w/ canopy area about 80 sq. ft. • 80 / 20 = 4 emitters


Calculate FR per emitter

5. Divide total FR for the plant by the number of emitters selected per plant to get the flow rate per emitter.

Example plant A: FR / 4 = 2.3 gph / 4 = 0.58 gph• Since there is no 0.58 gph emitter, a 0.50 gph emitter

could be selected and to avoid under-watering, 5 emitters (instead of 4) could be used.

• Total FR would then be 2.5 gph and total irrigation in the 4.2 hour runtime would be 2.5 x 4.2 = 10.5 gallons which is only 7 % above the IR


Emitter placement

• Small plants (D < 3 feet) – near base

• Larger plants (shrubs and trees) – generally ½ the distance from the base to outer edge of canopy (Toro)


Xeriscape Plant Examples


No to Very Low Irrigation

K = 0.10 (10% of ETr) or less


Yuccas


Cylindropuntia imbricata (tree cholla)


Chamaebatiaria millefolium (fernbush)


Rhus trilobata (3-leaf sumac)


Fallugia paradoxa (Apache plume)


Amelanchier utahensis (Utah serviceberry)


Chilopsis linearis (willow-leaf catalpa)


Berlandiera lyrata (chocolate flower)


Low Irrigation

K value = 0.15 to 0.25


Hylotelephium telephium (autumn joy sedum)


Hesperaloe parviflora (red yucca)


Juniperus scopulorum (Rocky Mountain juniper)


Penstemon palmeri (Palmer penstemon)


Penstemon pinifolius (pineleaf penstemon)


Perovskia atriplicifolia (Russian sage)


Penstemon ambiguus (bush penstemon)


Mirabilis multiflora (giant four o’clock)


Medium Irrigation

K = 0.25 to 0.35


Caryopteris clandonensis (blue mist)


Salvia greggii (cherry sage)


Prunus besseyi (western sandcherry)


Zinnia grandiflora (desert zinnia)


Penstemon strictus (Rocky Mountain penstemon)


Penstemon barbatus (scarlet bugler penstemon)


Penstemon eatonii (firecracker penstemon)


Melampodium leucanthum (blackfoot daisy)


Liatris punctata (dotted gayfeather)


Higher Irrigation

K = 0.40 – 0.60


Spartium junceum (Spanish broom)


Teucrium arogrium (Greek germander)


Agave utahensis (Utah agave)


Centranthus ruber (Jupiter’s beard)


Helianthus maximiliani (Maximilian sunflower)


Gaura lindheimeri (gaura)


Other Considerations

• The K value shown for each species represents the adjustment factor to ETr for the minimum irrigation level providing acceptable quality (subjective rating) for that species.

• Most plants will exhibit a higher rate of ET (and more growth) if provided with more water.

• However, excessive watering may not enhance plant quality and in some cases, it can be detrimental to quality (root rot and other diseases, rangy appearance, etc.).

• Keep in mind that a xeriscape is dynamic and water requirements may change over time as the plants grow or die, need replacement, etc.


Thank you!

Farmington ASC website: http://farmingtonsc.nmsu.edu


Documents

Irrigation of Xeric-Adapted Landscape Plantsirrigationmanagement.nmsu.edu/documents/irrigxeric... · Fallugia paradoxa Apache plume 0.05 Helianthus maximiliani Maximilian sunflower