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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
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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.
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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
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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.
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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
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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
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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,
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