Growing the best phalaenopsis, part 4 - Michigan State University

CULTURE CORNERGrowing the Best PhalaenopsisPart 4: A Complete Production ScheduleBy Matthew Blanchard, Roberto Lopez, Erik Runkle, PhD, and Yin-Tung Wang, PhDTOP An example of mass production ofyoung phalaenopsis plants grown incommunity pots at a commercial nursery inThe Netherlands.ABOVE Young plants spaced aftertransplanting into 5-inch (12.5-cm) pots.OPPOSITE Remay cloth can be used afterplanting to reduce light transmission asplants acclimate to a new growingenvironment.MATTHEW BLANCHARDMATTHEW BLANCHARDIN THE PREVIOUS THREE ISSUESof Orchids, we have described theoptions for purchasing phalaenopsisstarting material and discussed theimportant cultivation techniquesinvolved in producing a flowering crop.In conclusion of our four-part series,we will put all of this informationtogether and provide a simplifiedproduction schedule that can beimplemented to fit your growingenvironment.The production of phalaenopsisorchids can be divided into threephases:Phase 1. Vegetative cultivation athigh temperatures of 82 to 90 F (28 to32 C)Phase 2. Spike induction at low daytemperatures of 63 to 77 F (17 to 25 C)Phase 3. Finishing at 63 to 79 F (17to 26 C).Depending on your greenhousefacilities, climate and choice of startingplants, the production of floweringpotted phalaenopsis can involve allthree of these phases or may be limitedto only one or two. As discussed inthe January 2007 issue of Orchids, oneoption for growers is to purchasenonflowering immature plants thatrequire additional vegetative growthbefore cooling and spike induction. Agrower who chooses this option willuse all three production phases.Alternatively, the vegetative phase canbe omitted by purchasing mature plantsof flowering size that are ready for thecooling phase. Growers who adopt thisproduction strategy purchase plantsthat can be induced to spike soon afterplants arrive and then finished inflower for a particular date. In somecircumstances, plants with a visiblespike that have already receivedcooling can be purchased. Theseplants are termed “pre-spiked” and arefinished by the grower for flowering.Many large commercial growers ofphalaenopsis import young plants fromother countries, either in flasks or assmall bare-root plants. The first articleof this series (January 2007) containsmore information on importing plantsfrom overseas. There are also several266 ORCHIDS APRIL 2007 WWW.AOS.ORG

MATTHEW BLANCHARDdomestic producers of young plantswho can provide actively growingplants in media.Since May 2005, nurseries in theUnited States have been permitted toimport potted phalaenopsis of all sizesgrown in approved media from Taiwan.Although these plants were originallyshipped to the United States byairfreight, due to high transportationcosts most plants are now imported bysea freight. During transport by sea,potted phalaenopsis are packed in airconditionedcargo containers andshipped in complete darkness for threeto four weeks. When done properly,plant loss is less than five percent andmature plants can be immediatelyinduced to flower upon arrival at thedestination greenhouse. Research iscurrently being performed at TexasA&M University to learn how plantquality can be further improved.With these options for purchasingplant material in mind, let’s now discussa simple schedule for producing a cropof flowering phalaenopsis.PHASE 1: VEGETATIVE GROWTHA grower who purchases youngimmature plants will begin productionof phalaenopsis with vegetativecultivation. For the large-floweredhybrids and clones, this plant materialgenerally will not flower uniformly untilplants have an average leafspan of 10inches (25 cm) or greater. Therefore,plants are grown at high temperaturesto promote leaf development and inhibitflowering.Plants purchased in flasks are oftentransplanted into square or rectangularcommunity pots, with about 40 or 50plants per tray. After approximately 20to 25 weeks of growth at hightemperatures, plants are then transplantedinto individual containers forthe next stage of vegetative growth.Plant material with an average leafspanof 8 inches (20 cm) is oftentransplanted into 5-inch (12-cm) pots.Spacing depends on plant size andgrower preference, but early in theproduction phase, plants can be spacedpot-to-pot.Following transplanting, severalirrigations may be necessary tosufficiently moisten the substrate,depending on the environmentalconditions and medium composition.Due to the low water-holding capacityof fresh bark, newly transplantedmaterial will need to be frequentlychecked for watering until the mediumWWW.AOS.ORG APRIL 2007 ORCHIDS 267

CULTURE CORNERbegins to hold more moisture.Alternatively, the addition of asurfactant (or a few drops of dishwashingliquid) to the water can reducethe surface tension of the media andimprove water absorption. Media withhigh water-holding capacities need lessfrequent watering. If bare-root plantsare planted in moist sphagnum moss,no watering is needed until the mosshas become nearly dry. Light sprinklingdaily also helps plant recovery duringthe first few weeks after transplant.Some growers place a thin layer ofpolyethylene fabric (e.g., Remay cloth)over benches for one to two weeks afterplanting bare-root plants to create diffuselight levels less than 1,000 foot-candles(200 µmol•m -2 •s -1 ) and to increasehumidity. This strategy helps tominimize plant stress and reduce plantloss after planting.Young plants are grown at hightemperatures in the range of 82 to 90 F(28 to 32 C), at least during the day, topromote vegetative growth and inhibitflowering. If environmental conditionsare favorable, plants with a leafspan of4 to 5 inches (10 to 12.5 cm) requireapproximately 22 to 27 weeks to reachflowering size. This duration dependson temperature, the initial leafspan,fertility and the size desired before theinduction of flowering. On average, anew leaf will emerge every six weeksand will reach maturity after 10 weekswhen grown at these high temperatures.As the growing temperature decreases,the rate of leaf development slows.When importing mature bare-root plantMATTHEW BLANCHARDMATTHEW BLANCHARDmaterial from overseas, providing fourto six weeks of growth in a warmenvironment after planting will bebeneficial for rooting and subsequentflowering.Growers should monitor light levelswith a light meter and adjust shadingto provide between 500 and 1,500 footcandles(100 to 300 µmol•m -2 •s -1 ) ofdiffused light at canopy level. Plantsshould be spaced as necessary tominimize leaf overlap and allow foradequate air circulation. Duringspacing, it is also a good idea to sortplants according to leafspan. Plantswith a small leafspan will requireadditional time before the onset of thecooling phase.PHASE 2: COOLING When plantshave five to seven leaves and aminimum leafspan of 10 inches (25 cm),the cooling phase can begin to inducespiking. A grower that purchasesmature potted plants may begin withthis phase of production. Plants canbe cooled at temperatures in the rangeof 63 to 77 F (17 to 25 C) for approximatelyfour to six weeks. At the lowerend of this temperature range, plantsmay produce two or more spikes. Inmost phalaenopsis hybrids, a spike (thepotentially flowering stem) will usuallybecome visible after three or four weeksof cooling. However, longer durationsmay be required for some hybrids orwhen plant material is smaller.Cooling may take place in the samegreenhouse section as the vegetativephase if all plants in that section are tobe induced into flower. When only aportion of plants are to be induced intoflower, a separate greenhouse sectionis needed for cooling. Providing lowtemperatures to young plants caninduce variable premature spiking andslow down vegetative growth, both ofwhich are undesirable.PHASE 3: FINISHING The finishingphase describes the period fromspike emergence through spikedevelopment and flowering. Aftercooling, plants may either be transferredto a separate finishing area forflowering or remain in the samegreenhouse section used during thecooling phase. Plant spacing can be thesame as during the cooling phase.Temperatures in the range of 63 to 79 F(17 to 26 C) are used during finishing.Since flower bud initiation begins whenthe spike has reached about 2 inches(5 cm) in length, maintaining temperaturesbetween 63 and 68 F (17 to 20268 ORCHIDS APRIL 2007 WWW.AOS.ORG

C) until the spikes are 12 inches (30 cm)or longer can increase the number offlowers. Some hybrids grown at a coolertemperature may also have increasedlateral branching of the inflorescence.It is important to avoid extendedexposure to temperatures above 79 F(26 C) during this final phase. Hightemperature can reduce flower budnumber and flower size, and flowerbuds may abort. In addition, prolongedexposure to high temperatures caninduce a vegetative air plantlet to formon the spike (referred to as a “keiki”)rather than flower buds.Following spike emergence, the rateof development toward flowering iscontrolled by the average daily temperature.For example, in researchconducted at Michigan State University,as the average daily temperatureincreased from 57 to 76 F (14 to 26 C),the average time from spike emergenceto flowering decreased from 217 to 54days (Table 1). This time variessomewhat by cultivar, with someflowering earlier and some a few weekslater. Based on this information andgrower experience, the greenhousetemperature can be raised or loweredto finish a phalaenopsis crop for adesired flowering date.An important component of thefinishing phase involves staking andpreparing phalaenopsis for an orchidshow or sale. Properly staking theinflorescence will affect how the plantis presented at a show or sale, thusimproving consumer appeal. Inaddition, staking will also minimizeplant damage during packaging andtransport. Plants should be staked nolater than when the lowest flower budon an inflorescence has reached thesize of a marble. The stick (bamboo orother materials) used for stakingshould not be taller than the lowestflower bud and can be attached to theinflorescence using clips or ties. At thetime of staking, plants are often sortedbased on a predetermined qualitygrading scale (i.e., number of spikes andflowers or spike length).POST-HARVEST When plantshave at least one or two open flowers,they are ready for display or sale andcan be packaged for transport. Thepreparation of plants for shipping andsales display is a labor-intensiveprocess that can involve many tasks.Phalaenopsis leaves are sometimescleaned and plants are placed intodecorative ceramic or terracotta potsROBERTO LOPEZERIK RUNKLEOPPOSITE TOP Staking plants is animportant step during the finishing phase.Plants should be staked no later than whenthe lowest flower bud on an inflorescencehas reached the size of a marble.OPPOSITE ABOVE Mature plants during thecooling phase with spike initiation.TOP Phalaenopsis placed into decorativeterracotta pots and ready for shipping to aretail store.ABOVE Three phalaenopsis plantscombined into a decorative container inJapan.Table 1. The effect of average daily temperature on the average time from visible spike toflower in several phalaenopsis hybrids grown at Michigan State University.Temperature F (C)Time from Visible Spike to Flower (Days)57 (14) 21763 (17) 14068 (20) 9773 (23) 7176 (26) 54WWW.AOS.ORG APRIL 2007 ORCHIDS 269

CULTURE CORNERMATTHEW BLANCHARDwith sphagnum moss on the surface ofthe growing medium. A label with careinformation is often affixed to thesupport stick and leaf shine may beapplied to the foliage before the plantis placed into a protective sleeve.Potted phalaenopsis are perceived byconsumers as elegant plants with highornamental value. As a result, all ofthese steps can add value to theproduct and influence how the plant ispresented to the consumer.Flowers of all orchids, includingphalaenopsis, are extremely sensitiveto low concentrations of ethylene, anodorless, colorless gas released byripening fruits and flowers, cigaretteand wood smoke and exhaust from gasheaters and combustion engines.Ethylene concentrations as low as 0.1parts per million will cause allphalaenopsis flowers and buds to falloff within three days. To avoid ethylenedamage, growers should preventexposing plants to external sources ofethylene and also provide adequateventilation in the greenhouse. Researchat Texas A&M University showed thattreating flowering phalaenopsis withanti-ethylene products such as 1-methylcyclopropene (1-MCP, or Ethyl-Bloc) at 0.2 parts per million for sixhours at 77 F (25 C) protects flowersfrom ethylene concentrations as highas 10 parts per million. However, theduration of protection from 1-MCP isshort (seven days at 77 F or 25 C) andthe duration of protection declines astemperature increases. The use of 1-MCP or EthylBloc is generally limitedto commercial greenhouse growers.Hobbyists and growers have manyoptions to produce flowering phalaenopsisorchids. Immature plants willcost less than mature ones, but willrequire a longer production time andadditional expenses. In temperateclimates, one of the largest productionexpenses is the energy for heating agreenhouse to promote vegetativegrowth. Growers who wish to reduceproduction time and heating costs maychoose to purchase more expensiveplant material that is of flowering sizeand can be immediately forced toflower. This option would avoid theneed to grow plants at a hightemperature to promote additionalvegetative growth.A simplified schedule for theproduction of phalaenopsis in 5-inch(12.5-cm) pots is provided in Table 2.From this, and with the informationprovided in our four-part series, youcan develop a production schedule tofit your greenhouse conditions andproduce a crop of flowering pottedphalaenopsis orchids. Although thisarticle has focused on environmentalcontrol of growth and flowering,cultural factors such as watering,fertility, pest and disease control andselection of an appropriate medium arealso highly important for producing asuccessful and profitable crop.AcknowlegmentsWe would like to thank the Fred C.Gloeckner Foundation, the American OrchidSociety, Matsui Nursery, Taiwan SugarCorporation, Project GREEEN and privategreenhouse companies that support orchidresearch.(This article was adapted from a seriespublished in Greenhouse Grower magazine.)270 ORCHIDS APRIL 2007 WWW.AOS.ORG

MATTHEW BLANCHARDMatthew Blanchard and Roberto“RoLo” Lopez are PhD graduateassistants at Michigan State University.Erik Runkle, PhD, is assistant professorand floriculture extension specialist atMichigan State University (e-mailrunkleer@msu.edu). Yin-Tung Wang,PhD, is professor of floriculture atTexas A&M University (e-mail ytwang@tamu.edu).OPPOSITE Phalaenopsis carefuly wrappedfor transit.ABOVE Phalaenopsis prepared for displayand sale at Nagoya Orchid Gardens inNagoya, Japan.Table 2. A simplified schedule for the production of flowering potted phalaenopsis orchids in 5-inch (12.5-cm) pots.Production PhaseUnitsVegetativeGrowthC oolingFinishing (to First Flower)DurationWeeksUntil PlantMaturity4 to 6201410TemperatureF 82to 9063to 77636873C 28to 3217to 25172023LightIntensityFoot-Candles500to 1,5001,000to 1,5001,000 to 1,5002µ mol•m-• s-100 to 30 01 200to 300200 to 300WWW.AOS.ORG APRIL 2007 ORCHIDS 271