ANR-1144

A L A B A M A A & M A N D A U B U R N U N I V E R S I T I E S

Visit our Web site at: www.acesag.auburn.edu

Greenhouse Productionof Gerbera Daisies

Introduction

Gerbera daisies (Gerberajamesonii) are useful as cutflowers, pot crops, and beddingplants planted outdoors in fullsun. They can be planted in dishgardens, mixed containers, patiopots, or traditional containers foruse as holiday and seasonalgifts. The rich green, leafy fo-liage gives rise to 31⁄2- to 5-inchblooms that may be red, orange,yellow, salmon, pink, or white.

HistoryRobert Jameson, a Scotsman,

first discovered gerbera daisieswhile operating a gold mine nearBarberton in the Transvaal area ofSouth Africa in 1880. He donatedplants to the Durban BotanicalGardens, and the curator of thegardens, John Medley Wood, sentspecimens to Harry Bolus in CapeTown, South Africa, for identifica-tion. Bolus then sent specimensto the Royal Botanical Gardens atKew in England, with the suggest-ed scientific name Gerbera jame-sonii. Beginning about 1890 inEngland, Richard Irwin Lynch car-ried out breeding programs thatresulted in many improvements.Gerberas soon became popular inthe Netherlands, where much ofthe modern breeding has beenaccomplished.

Gerberas were not producedin North America until the early1920s. Extensive breeding at theUniversity of California at Davisduring the 1970s led to manyplants suitable for garden use.However, breeding in Floridaand Europe focused on develop-ing long-stemmed cultivars forgreenhouse cut flower produc-tion. In fact, much of the pro-duction today in Europe andJapan is for cut-flowers. In theU.S., California and Florida arethe leading states in the produc-tion of cut flowers and tissue-cultured stock. The majority ofcut gerberas, however, comefrom Columbia and surroundingcountries in South America, withsubstantial quantities comingfrom the Netherlands.

Happipot was the first seed-propagated cultivar that hadflower stems short enough to beused in 5- or 6-inch pots. It wasintroduced by Sakata SeedCompany of Japan in the early1980s. About the same time,Sunshine Research andDevelopment selected plants forpot culture, resulting in theSunshine and Sunburst series.These are tissue-cultured culti-vars that are marketed throughseveral laboratories. The trendtoday is toward seed-propagatedplants. Cultivars currently avail-able include the Small pot ger-beras from Earl J. Small Com-pany, the Nain series from ParkSeed Company, and the ValleyHeart series from Valley HeartGardens. Current breedingstrives for vigorous growth,compact habit, and continuousflowering on sturdy stems.

ARCH

IVE

http://www.aces.edu/http://www.aces.edu/

2

CultivarsGerbera daisy cultivars for

greenhouse production havebeen developed in differentplant sizes to accommodate awide range of container sizes.Groups of cultivars (cultivar se-ries) have been bred for 1- to 3-gallon containers. These arelarge plants with 4- to 6-inch-di-ameter flowers on 18- to 24-inchstems. Series are also available insizes appropriate for 5- to 6-inchpots and 4- to 5-inch pots.

Several different flower typeshave been developed in ger-beras. Most cultivars have singleor daisy-type flowers composedof one or two rows of long outerray flowers surrounding a tightgroup of short disk flowers withinconspicuous petals. An inter-mediate flower type has one ortwo rows of long outer ray flow-ers, several rows of medium-length ray flowers, and then atight group of short disk flowersin the center. Finally, the crestedflower type has many ray flow-ers almost covering the diskflowers, but the outer rows arelonger than the inner rows sothe flower head is rounded.

When purchasing gerberasfor production, choose cultivarsizes based on the container sizedesired. Also consider fast croptime, ease of shipping, long-last-ing quality, and a large selectionof flower colors and types. Youmay choose to select flower col-ors that are suitable for differentseasons—for example, orangeand red for fall and winter andyellow, pink, and salmon forspring and summer.

Seed PropagationGerbera seeds, of which

there are 6,000 to 8,000 seed perounce, are expensive, delicate,and sensitive to germinatingconditions. Considering that thecrop requires 14 to 18 weeksfrom seed to flower, many small-

to medium-sized growers orderestablished, plug-grownseedlings from specialist propa-gators. Seeds should comepacked in moisture-proof pack-ages and should be stored undercool conditions away fromstrong sunlight until sown. Oncethe package is open, all seedsshould be sown at once becausethey lose their viability veryquickly when exposed to roomconditions. Though it is not ad-vised, unused seed can be re-sealed in the package and storedin a refrigerator for a short time.Recommended sowing mediavaries, but most consists of 40 to 60 percent peat and 40 to 60percent perlite with a 5.8 to 6.0pH, 0.8 mmhos/cm E.C. (2:1extraction method), and somefertility.

Gerbera seed can be sown inopen flats or in a variety of plugflat sizes. However, transplantingfrom open trays requires morelabor and delays establishmentin the new containers. The morecommon practice is to sow intoa variety of large plug trays thathave 72 to 288 cells per tray.Some growers sow into small-celled trays and then transplantto larger trays or pots. This al-lows the seedlings to be sortedby size for a more uniform cropbut requires more labor. Waterthe sowing media before sow-ing, and cover the seed with athin layer of No. 3 fine-gradevermiculite afterward.

Germinate the seed, using asystem that maintains relativehumidity as close to 100 percentas possible. Use bottom heat tomaintain 70° to 75°F media tem-perature. Some growers placetrays in plastic bags or use fogsystems; others use germinationchambers at 73° to 75°F for 4 to5 days. Trays should receive atleast 12 hours of incandescentlight per day while in germina-tion chambers. Remove the plas-tic bags and move the seedlings

into the greenhouse 7 to 14 daysafter sowing or when completegermination has occurred.

Night temperatures for grow-ing on seedlings in the green-house should be 68° to 72°F. Atthis point, protect the seedlingsfrom full sun by providing lightshade (30 to 40 percent) and ahigh greenhouse humidity (70 to75 percent). During dark periodsof the year, supplemental high-intensity discharge (HID) lightingwill speed seedling growth.Apply HID lighting for at least14 hours per day at 300 to 500footcandles (60 to 80 W/m2).

Begin fertilizing the seed-lings, using a low ammoniumfertilizer (15-5-15) about 10 daysafter germination at 50 to 75ppm nitrogen. Gradually in-crease the fertilizer concentrationto 100 to 150 ppm nitrogen. Theyoung foliage is sensitive to fer-tilizer burn, so rinse the foliagewith clear water immediatelyafter fertilizing. Monitor themedium pH to make sure that itdoes not rise above 6.2 or fallbelow 5.5. High pH typically re-sults in micronutrient deficiency,and low pH can result in calci-um or magnesium deficiency.Some growers transplantseedlings to large cell packs,21⁄2-inch pots, or Jiffy-Stripsabout a month after sowing orwhen the seedlings have twomature leaves.

Growing PlugsWhether the gerbera crop is

started from seed in house or or-dered from a specialist propaga-tor, seedlings should be trans-planted to the final container 6to 7 weeks from sowing orwhen they have four to five ma-ture leaves. An additional weekmay be required if the cropspends the principal amount oftime in the winter. If plugs arereceived from a specialists prop-agator, remove the trays from

ARCH

IVE

3

the shipping boxes, and inspectthem for insects and diseases.Then place them in the green-house, check to see if they needwater, and allow them to accli-mate for a day or two beforetransplanting them. However,transplant the plugs after nomore than 2 days so the plantsdo not become root-bound.Overgrown transplants takelonger to finish and are smallerat flowering.

Transplanting depth is veryimportant. Plant the soil ballslightly high so that the crown isnot covered with soil after it iswatered. Applying a broad-spec-trum fungicide drench is a com-mon practice at this time.

Potting MediaPotting media used for ger-

beras should be loose and welldrained with a high percentageof organic matter. Many growersuse 50 to 80 percent peat withperlite, vermiculite, calcine clay,or course sand added for the re-maining percentage. Dolomiticlimestone should be added to apH of 5.8 to 6.0. Superphosphateat 4.5 pounds per cubic yard andmicronutrients at the manufac-turers’ recommended rates arealso added. Because gerberasare fairly heavy feeders, a startercharge of calcium and potassiumnitrate is often added to the mixat 1 pound of each per cubicyard. Good grades of commer-cially available peat-lite mixescan also be used.

After potting, place theplants pot-to-pot where they willreceive the maximum amount oflight. Gerberas can be wateredand fertilized overhead for about4 weeks before they must beplaced at final spacing.

FertilizationIf a starter amount of fertiliz-

er was added to the medium atmixing, do not begin fertilizinguntil roots reach the sides andbottom of the pot. Many sourcesrecommend applying a low-am-monium, balanced fertilizer suchas 15-16-17 (peat-lite special) or15-15-18 on a constant liquid fer-tilization basis. Young plantsshould be fertilized with 100 to150 ppm nitrogen for the first 2to 3 weeks. This rate should beincreased to 150 to 200 ppm ni-trogen during the winter monthsor 200 to 250 ppm nitrogen dur-ing the summer months. Adjustthe nitrogen application ratebased on plant growth. Exces-sive nitrogen can cause the fo-liage to overgrow and hide theflowers. Excellent results havebeen obtained using slow-re-lease fertilizer such as Osmocote14-14-14 (3 to 5 pounds peryard3) in combination with thelower liquid fertilization rate.

Growers should manage thefertility program for gerberadaisies by performing a soil testand tissue analysis at least oncea month. Floral crop soil testsprovide medium pH, solublesalts, and levels of macro- andmicronutrients. The soluble saltsfor gerberas should be 1.2 to 1.5mmhos/cm E.C. (2:1 extractionmethod). Low readings oftenmean not enough fertilizer isbeing applied, application is tooinfrequent, or a combination ofboth. High readings may meantoo much fertilizer is being ap-plied, application is too fre-quent, not enough water is

applied to wet the medium andobtain drainage, drainage ispoor, or a combination of theseconditions exists. Tissue analysisprovides information about whatnutrients are being absorbed bythe roots and transported to thefoliage. Table 1 lists guidelinesfor plant analysis values.

Many of the fertility prob-lems encountered with gerberasare pH-related. Monitor themedium pH weekly to ensurethat it does not rise above 6.2 orfall below 5.5. High pH typicallyresults in micronutrient deficien-cy, frequently iron. A spray ap-plication of iron chelate at themanufacturer’s recommendedrate will help alleviate thechlorosis symptoms, but stepsmust be taken to lower the pH.Repeated applications of an acidresidue fertilizer such as 20-10-20 help.

Low pH can result in calciumor magnesium deficiency.Repeated applications of a basicresidue fertilizer such as calciumnitrate help. Magnesium defi-ciency can be alleviated using1.5 pounds magnesium sulfate(Epsom salts) per 100 gallons asa drench.

TemperatureA night temperature of 68° to

70°F is preferable until plants es-tablish a root system, usually inthe first 3 to 4 weeks. Tempera-tures can then be reduced to 65°to 68°F at night for the next 2 to3 weeks, followed by 60°F tofinish. Ventilation can begin dur-ing the day at 75°F. Slightlywarmer or cooler temperatures

Table 1. Plant Analysis Guidelines for Gerbera Daisy (Dry Weight Basis)

Nutrient Concentration Nutrient Concentration(percentage) (ppm)

N 1.50 to 3.50 B 20 to 60P 0.20 to 0.50 Cu 6 to 50K 2.50 to 4.50 Fe 50 to 200Ca 1.00 to 3.50 Mn 40 to 250Mg 0.20 to 0.70 Zn 25 to 200

Source: Plant Analysis Handbook, Georgia, 1988.

ARCH

IVE

4

can be used to speed or slowthe crop, but extremely higheror lower temperatures will delayfinish. Elongation of the flowerstalk is sensitive to positive ornegative DIF either applied gen-erally or as an early morningapplication.

Relative HumidityBotrytis can be a serious

problem with gerberas duringdark, cool periods in winterwhen the greenhouse humidityis high. Take steps to keep thehumidity below 70 percent dur-ing the day and below 85 per-cent at night. Good internal aircirculation in the greenhouse atnight and ventilation during theday are essential. High humidityappears to contribute to flowerstalk stretching.

LightGerberas require high light

intensities for good-qualityplants and high flower bud num-bers. For this reason, they aremostly produced in the springand summer, with the greatestamount of production for thespring market. Plants grow bestin full sun during the fall, winter,and spring. Light shade (30 to 40percent) can be used to reduceexcessive greenhouse tempera-tures in the summer, but becareful not to apply too much.Plants receiving too little lighthave pale green, stretched fo-liage and long, weak flowerstems. Plants receiving too muchlight have compact, slightly yel-low foliage with short flowerstems often hidden in thefoliage.

Gerberas appear to respondonly slightly to photoperiod.Short days tend to speed flowerproduction, while long daysdelay flowering. However, manygrowers produce gerberas withno photoperiod control. Somegrowers extend the photoperiod

cause leaves to stretch. Exactspacing is difficult to recom-mend because of differences inpot size and cultivar sizes.However, begin with a 6- by 6-inch minimum for 4- to 41⁄2-inchpots, an 8- by 8-inch minimumfor 5-inch pots, and a 10- by 10-inch minimum for 6-inch pots.

Chemical GrowthRetardants

B-Nine is the growth retardantof choice for gerbera growers.Whether using 4-, 5-, or 6-inchpots, apply the first application asa foliar spray 10 to 14 days afterpotting to the final container at2,500 ppm. B-Nine at 1,000 to1,500 ppm can also be applied inthe plug stage when seedlingshave 4 to 5 mature leaves. Thenumber of applications dependson the season, cultivar, and potsize (Table 2). A second applica-tion of B-Nine may be desirableat 2,500 ppm during the hot sum-mer months, depending on lightlevels and watering practices. Donot apply B-Nine in the last 4weeks before flowers open be-cause flower size and shape maybe adversely affected.

from October through March for4 weeks only to get more vegeta-tive growth before flowering.Extending the photoperiod forlonger than 4 weeks can result inexcessive foliage growth. Duringthe seedling and pot-to-pot stagein winter, supplemental HIDlights can be applied for at least14 hours per day.

WateringGerberas should receive a

thorough watering and then beallowed to dry somewhat. Thislimits growth of the flower stemand discourages soilborne dis-eases. Gerberas should never beallowed to wilt, however. Plantsallowed to dry out too much andtoo frequently have short flowerstems that may be hidden in thefoliage. It is also a good practiceto water early in the day so thefoliage is completely dry beforeevening.

Plant SpacingAfter 4 weeks pot-to-pot,

space the plants so that plenty oflight reaches the crown andthere is free air movement. Tightspacing can delay flowering and

Table 2. Seasonal B-Nine Applications to Gerbera Daisy

Pot size (in.) Period Treatment

41⁄2 to 5 Fall to spring 1 to 2 applications6 Fall to spring 1 application41⁄2 to 5 Summer 2 to 3 applications6 Summer 1 to 2 applicationsARCH

IVE

5

Crop SchedulingThe timing of Gerbera daisy

crops depends on several factorsincluding cultivar, environmentalconditions, pot size, and culturalpractices. Growers should keepdetailed records of crop perfor-mance and timing to improve fu-ture scheduling efforts. Gener-ally, 4-inch pots require 8 to 11weeks, 5-inch pots require 9 to12 weeks, and 6-inch pots re-quire 10 to 13 weeks from trans-planting to finish in the summer.An additional week is requiredduring the winter. A general out-line of gerbera daisy crop sched-uling is shown in Figure 1.

Crop Problems

InsectsLeaf miners, spider mites, cy-

clamen mites, whiteflies, aphids,and thrips are the main insectpests of gerberas.

DiseasesPowdery mildew, Phytoph-

thora (crown/root rot), Botrytis,impatiens necrotic spot virus,and bacterial blight are the maindisease problems of gerberas.

Specific control measures forinsect and disease problems canbe found in the Alabama PestManagement Handbook,Volumes 1 and 2 (ANR-500A and500B), or contact your countyExtension agent.

Common Problems and Their Causes✽ Foliage too large or flower stems too long:

Light intensity too lowAmmonium fertilizer too highGrowth retardant too lowCultivar selection incorrect

✽ Flower stems too short:Growth retardant excessive or latePlants too drySoluble salts too highGrowing temperature too cold

✽ Flowers distorted:Cyclamen mite or thrips problemSoluble salts too highTemperature too high or too low

✽ Plants stunted or failing to grow:Drainage or aeration poor; plants too wetSoil temperature too lowGrowth retardant too highPlants planted too deep

✽ Plants wilting or dying:Plants planted too deep—crown rot developsRoot rot

Gerbera daisies are some-what more of a challenge togrow than are many greenhousepot crops produced in thespring. Careful attention to de-tails and accurate crop recordscan help growers reduce produc-tion time and increase productquality. However, gerberas canbe worth the effort because de-mand for a high-quality producthas not been met by producersin many markets.

Figure 1. Gerbera Daisy Production Schedule

6 to 8 weeks 8 to 10 weeks

2 to 414 days 2 weeks weeks 4 weeks 4 to 6 weeks

Sow Germi- Larger Final Pot-to-pot Finishnation Flat Container

ARCH

IVE

J.R. Kessler, Jr., Extension Horticulturist, Assistant Professor, Horticulture,Auburn University

Trade names are used only to give specific information. The Alabama Cooperative ExtensionSystem does not endorse or guarantee any product and does not recommend one product in-stead of another that might be similar.

For more information, call your county Extension office. Look in your telephone directoryunder your county’s name to find the number.

Issued in furtherance of Cooperative Extension work in agriculture and home economics, Acts of May 8 and June30, 1914, and other related acts, in cooperation with the U.S. Department of Agriculture. The AlabamaCooperative Extension System (Alabama A&M University and Auburn University) offers educational programs,materials, and equal opportunity employment to all people without regard to race, color, national origin, religion,sex, age, veteran status, or disability. UPS, 3M14, New Feb 1999, ANR-1144ANR-1144

ARCH

IVE

http://www.aces.edu/