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POT PLANTS

A ZZ plant isgood for interiorscapesbecause of its glossy leaves,limited pestproblems andperformanceunder low light.

By Matthew Blanchard and Roberto Lopez

ZZ plant is an easytough indoor use

CharacteristicsNative to East Africa, the ZZ plant is hardy in

USDA Hardiness Zones 9b-11 and reaches 2-3feet tall and 3 feet wide. The plant produces ashort, yellow-brown flowering spadix at itsbase, but the flowers are not showy.

Beneath the soil, the ZZ plant produces roundrhizomes that function to store water. The for-mation of these rhizomes makes it an interestingplant to propagate because they often developduring the rooting of vegetative cuttings.

The ZZ plant can be propagated vegetativelyeither by division or cuttings. Because divisionrequires a grower to begin with several largestock plants, this propagation method is oftenimpractical. With this in mind, we focused onusing vegetative cuttings.

Study results from MSUBest type of cuttings. The goal of one of our

studies was to determine the best type of vegeta-tive cuttings that would root and produce thegreatest number of rhizomes during propaga-tion. Five types of cuttings were harvested fromstock plants: two leaves with a node and stem;

Z Z plant, Zamioculcas zamiifolia, is becoming more popular as an indoor plant becauseof its glossy, dark-green foliage, limited disease and insect problems and performanceunder low light and restricted water availability. In 2002, the Florida Nursery, Growers

& Landscape Association named the ZZ plant a Florida Plant of the Year.The ZZ plant requires a relatively long growing cycle and high temperatures to produce

a marketable crop. For the past several years, researchers at Michigan State University havebeen investigating how to efficiently produce this plant.

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Four weeks aftersticking, all leafcuttings with orwithout stems or anode rooted andproduced onelarge rhizome.Stem cuttings didnot callus or root.

Effect of cutting type on rooting and finishingCUTTING TYPE

2 leaves with anode and stem Stem

Leaf with a node and stem

Leaf with no node

Leaf with a node

28 days after stick

16 weeks after transplant at 90˚F

Zamioculcas zamiifolia survivemost interior environments.

choice for

internode (stem); leaf with a node andstem; leaf without a node; and leafwith a node.

Cuttings were propagated in 72-cellplug trays filled with 50-percent com-mercial peat and 50-percent screenedcoarse perlite mix. The air and benchtemperature set point of the propaga-tion environment was 79˚F with a nat-ural photoperiod.

Four weeks after sticking, all leafcuttings with or without stems or anode rooted and produced onelarge rhizome. Stem cuttings didnot callus or root.

Rooted cuttings were transplant-ed into 4-inch pots and grown at90˚F under a 16-hour photoperiodprovided by high-pressure sodiumlamps. After 16 weeks, plants propa-gated from two-leaf cuttings with anode and stem were slightly largerthan the one-leaf cuttings.

More than one cutting. Anotherstudy was conducted to determineif more than one cutting could beobtained from a single leaf. Thiscould potentially reduce the num-ber of stock plants needed for cuttingproduction. Leaf cuttings were har-vested and horizontally cut acrossthe middle. The top portion of theleaf (apical cutting) and the bottomportion (basal cutting) were stuckapproximately 0.5 inches into thepropagation medium. Four weeksafter sticking, apical leaf cuttingsproduced more (three to five) smallrhizomes than basal leaf cuttings,which produced one large rhizome.

Impact of photoperiod. Onestudy determined if rooting or rhi-zome development was influencedby photoperiod during propagation.Apical, basal and full leaf cuttingswere stuck in propagation chambersunder 9- and 16-hour photoperiods.Rooting and rhizome number weredetermined five weeks after sticking.

Both photoperiod and cuttingtype (apical or basal) influenced thenumber of rhizomes that developed.Apical leaf cuttings consistentlydeveloped more rhizomes thanbasal leaf cuttings, regardless ofphotoperiod. The greatest rhizomenumber (3.9) occurred when apicalleaf cuttings were propagated undera 16-hour photoperiod. Full-leafcuttings developed three rhizomesregardless of photoperiod.

Daily light integral influence.Daily light integral (DLI) is the quanti-ty of light received each day and isexpressed as the number of moles oflight received per square meter per

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POT PLANTS

ZZ plant is best propagated using apical leaf cuttings under a 16-hour photoperiodand a minimum daily light integral of 2 moles per square meter per day.

Effects of daily light integral during propagation

mol m-2 d-1

2.2 1.3 0.9 0.6

Number of rhizomes after 43 days4.7 4.5 4.7 3.2

day (mol m-2 d-1). To determine theeffect of daily light integral on rooting,apical and basal leaf cuttings werepropagated under four differentwoven shade curtains (0, 30, 50 and70 percent shade). This providedfour different daily light integralenvironments, ranging from 0.6 to2.2 mol m-2 d-1.

After six weeks, apical leaf cuttingspropagated under a daily light integralof 0.9 to 2.2 mol m-2 d-1 produced anaverage 4.6 rhizomes compared toonly 3.2 rhizomes when cuttings wererooted under a daily light integral of0.6 mol m-2 d-1.

The ZZ plant is best propagatedusing apical leaf cuttings under a

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Effect of leaf cutting type and finishing

temperature on production

BasalApical

finishing temperature (˚F)

finishing temperature (˚F)

17 weeks after transplant

68 73

79 84

90

Left apical, right basal

ZZ plant should begrown at high dayand night growingtemperatures (76˚F-90˚F). Average dailytemperatures below76˚F delay shootemergence and thefinish production time.

finishing temperature (˚F)

CUTTING TYPE

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16-hour photoperiod and a mini-mum daily light integral of 2 molm-2 d-1. During propagation,maintain an air and bench tempera-ture set point of 75˚F-85˚F and alight intensity of 1,000-1,500 foot-candles. Overhead misting and steamor fog should be used to maintain highrelative humidity (90 percent).

Production guidelinesAfter propagation, plugs should be

transplanted into 4- to 6-inch pots filled with a commercial peat-based medium. When finishing a 4-inch crop, plant one rooted cuttingper pot. Larger pot sizes require addi-tional plugs.

A new shoot emerges from themedium 40-50 days after transplantat average daily temperatures of79˚F-84˚F. The number of newshoots that emerge from each leaf isrelated to the number of rhizomesat transplant. In our studies, leafcuttings that developed five rhizomesduring propagation initiated a similarnumber of new shoots two to threemonths after transplant. As shootsdevelop and new leaves unfold, theexisting rhizomes enlarge and addi-tional smaller rhizomes are formed.

One of the most importantrequirements for producing the ZZplant is providing a warm day andnight growing environment, in therange of 76˚F-90˚F. Average dailytemperatures below 76˚F will delayshoot emergence and the finish pro-duction time. The production timefor 4-inch plants grown at 84˚F is sixto eight months. Larger pot sizes orcooler production temperatureslengthen the growing time. Produc-

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Effect of cutting type and photoperiod on rhizome development during propagation

Apical half leaf9 hours, 16 hours

3, 3.9

Photoperiod:

No. of rhizomes:

Basal half leaf9 hours, 16 hours

1.3, 1.3

Photoperiod:

No. of rhizomes:

Full leaf9 hours, 16 hours

3, 3

Photoperiod:

No. of rhizomes:

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tion length can be reduced and fin-ished quality increased by plantingmore plugs per pot or using olderplugs with larger rhizomes.

During the finish stage, the lightlevel should be maintained at 1,000-2,500 footcandles using shade clothto provide diffuse light. When growingat the upper end of the temperaturerange, 86˚F-90˚F, the light levelshould not exceed 2,000 footcandlesto avoid scorching the leaf tips.Plants grown at a low relativehumidity (less than 50 percent) anda temperature above 79˚F may alsoshow leaf tip burn symptoms.

Irrigation and fertilizationThe ZZ plant grows best when the

growing medium remains moist, butnot completely saturated. Althoughthe crop can tolerate a dry medium,repeated moisture stress will reducegrowth and slow production time.

Fertilize with a balanced water-soluble fertilizer that supplies 125 to150 parts per million nitrogen atevery watering. A controlled-releasefertilizer can also be either incorpo-rated into or topdressed on thegrowing medium.

Plants have been observed to havevery few disease or insect problems.

Matthew Blanchard and Roberto“RoLo” Lopez are graduate assistants,Michigan State University, Department of Horticulture, A288 Plant and Soil Sciences Building, East Lansing, MI 48824;(517) 355-5191; mgblanch@msu.edu;lopezro4@msu.edu.

Production schedule*Propagation (72-cell liner)Duration: 4 weeksTemperature: 75˚F-85˚FLight intensity (footcandles):1,000-1,500

Finish in 4-inch potDuration: 24-32 weeks at 84˚FTemperature: 76˚F-90˚FLight intensity (footcandles):1,000-2,500

Duration: 32-40 weeks at 84˚FTemperature: 76˚F-90˚FLight intensity (footcandles):1,000-2,500

Finish in 6-inch pot

* Photoperiod for all is natural daylength or 16 hours.

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