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Agricultural Extension ServiceThe University of Tennessee

PB1634

Growing Orchidsin the Home

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Table of Contents

General Orchid Culture ......................................................................................................... 4Light..................................................................................................................................... 4Temperature ...................................................................................................................... 5Water ................................................................................................................................... 5Humidity............................................................................................................................. 5Air circulation.................................................................................................................... 6Fertilization........................................................................................................................ 6Growing Media .................................................................................................................. 6Repotting ............................................................................................................................ 6Containers .......................................................................................................................... 6

Pests and Diseases ................................................................................................................. 7Insects ................................................................................................................................. 7Fungal and Bacterial Disease.......................................................................................... 7Viruses ................................................................................................................................ 7Pest Control ....................................................................................................................... 7

Easy-to-Grow Orchids ............................................................................................................ 8Cattleya ............................................................................................................................... 8Phalaenopsis ...................................................................................................................... 8Paphiopedilum .................................................................................................................. 9Oncidiums .......................................................................................................................... 9

Buying an Orchid .................................................................................................................. 10Sources....................................................................................................................................11

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rchids are becoming increasingly popular asflowering houseplants due toimproved cultivars andaffordability. Once considereda rich person’s hobby, orchidsare now more affordable,thanks to recent advances inpropagation techniques. Sincethe first attempt to groworchids in the mid-1700s, theyhave had a reputation for beingdifficult to grow; however,many orchids are as easy togrow as houseplants. Orchidsare quite resilient, and cansurvive many years in the homewith proper care.

Orchids are in the familyOrchidaceae (or-kid-ACE-ee-ee). The orchid family includesmore than 900 genera andabout 25,000 species, makingit one of the largest families offlowering plants in the world.Orchids can be found in nearlyevery environment in theworld. Most of the orchidsgrown in the home are nativeto the tropical and subtropicalareas of South America. Theyare usually epiphytic, meaningthey grow on the sides of

trees, or lithophytic, meaningthey grow on rocks. Orchidsoriginating from temperateregions of the world aregenerally terrestrial, meaningthey grow in the soil.

Orchids are valued mostlyfor their exquisite flowers,which are available in a vastarray of colors from tints ofblue, yellow, white, orange andred to almost black. Someblooms are striped or spottedwith intricate combinations ofcolor. The blooms can lastfrom one week to four months,depending on the species.Given the proper growingconditions, some orchids maybloom continuously through-out the year, while others maybloom only once per year.

The foliage is usually amedium-green, but someorchids have beautiful leaveswith intricate mottling andvariegation. Many orchids arefragrant. While some may smelllike rotted meat, others havemore pleasant fragrances likelemon, orange, chocolate,hyacinth, cinnamon, winter-green, watermelon and coconut.

GeneralOrchid Culture

The cultural requirementswithin the orchid family varygreatly. The following informa-tion is a general guide forplants in the orchid family.Cultural requirements forspecific genera may differslightly.

LightThe most common reason

an orchid fails to flower isinadequate light. The plantmay grow and appear healthy,but if there is not sufficientlight, it probably will notbloom. In the horticultureindustry, light intensity ismeasured in footcandles (fc). Abright sunny day outdoorsmight yield 10,000 foot-candles. A window indoors,with northern exposure, mightyield as little as 100 fc. Or-chids are classified into threegroups according to their lightrequirements: high light (3,000or more fc), medium light(2,000-3,000 fc) and low light(1,200-2,000 fc).

Growing Orchidsin the Home

Linda M Seals, Graduate Research AssistantPaul D. Fortsch., Undergraduate StudentSusan L. Hamilton, Assistant Professor

Department of Ornamental Horticulture and Landscape Design

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The best place to groworchids in the home is on awindowsill. A south-facingwindow is the ideal location foroptimum results. An east-facing window would be next,then west and finally a north-facing window. If a windowsilldoes not provide sufficientlight, artificial lighting may beused. For optimum light trans-mission, clean the windowsfrequently, and clean thefoliage of dust as needed.

The plant itself is the bestindicator of proper light levels.If you have not been success-ful in getting your orchid tobloom, your first suspicionshould be too low light. Or-chids that are not gettingsufficient light will be a dull,dark green. Plants that arereceiving sufficient light willhave light to medium greenleaves. Although orchids donot generally receive too muchlight in the home environment,they may become sunburned ifplaced outdoors in direct sun.Sunburn may appear as black-ened or yellowish leaves, orleaves which are tinged red.

TemperatureTemperature is a critical

element in forcing orchids tobloom. Orchids are dividedinto four categories accordingto temperature preferences:warm-growing orchids thatprefer winter night tempera-tures no lower than 60F,intermediate-growing orchidsthat prefer a winter nightrange of 50 - 55Fs, cool-growing orchids that prefertemperatures no lower than45-50F and hardy orchidsthat can be grown outdoorsyear round.

A 10-degree drop intemperature at night is criticalto flowering in most orchids.Plants that are grown underconstant temperatures will notgrow or flower as well as thosegrown with fluctuating tem-peratures. If the plants aregrown outdoors in the sum-mer, the temperature will dropnaturally. For indoor plants,place the plants in a window-sill where a natural drop intemperature will occur. Plantsgrown under artificial lightingwill naturally receive thetemperature drop as the lightsare turned off in the evening.

WaterThe number one cause of

death in houseplants isoverwatering. Orchids are noexception. Most orchids preferthe growing media to drybetween waterings. There areseveral methods to determinewhen a plant needs watering.Insert your finger about 1 inchinto the soil near the center ofthe container. If the soil feelsdry, the plant needs water; if itis wet, wait. You can also pickup the pots to compare theweight of a dry pot versus awet pot. The pot will be lighterwhen it is dry. It is better tosoak the plant thoroughly andoccasionally than to waterfrequently with small amountsof water. To thoroughly wateran orchid, place it in a sinkand add lukewarm water untilthe water runs freely from thebottom of the pot. Avoid usingcold water (below 50F), sincethis can damage roots and cankill root hairs. About twice ayear, put your plants in theshower, and run warm waterover them for several minutes

to clean the dust off thefoliage.

HumidityOrchids love humid

conditions. They prefer a rangeof 50-70 percent relativehumidity. There are severalways to increase the humidityin the orchid’s environment.The simplest method is toplace several plants closetogether to increase the humid-ity of the air surrounding theorchids. Plants can also beplaced on trays containing alayer of pebbles or small gravel(Figure 1). Fill the tray with justenough water to fill the spacesbetween the gravel particles.The water in the gravel willincrease the humidity. Neverallow orchids to sit directly inwater, since this can cause rootdisease. You can also increasethe humidity by placing theplants in a bathroom window,by using plastic containersinstead of clay pots, or you can

Figure 1. Increase the humiditysurrounding a plant by placingit on a tray of gravel. Fill thetray with enough water to fill inthe spaces between the gravel.

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purchase a humidifier. Airconditioners and heaters drythe air, so avoid placing or-chids near vents or ducts.

Air CirculationAir movement is also

important to grow orchidssuccessfully. Air movementhelps to decrease the incidenceof fungus diseases and bacte-ria, and it aids in supplyingcarbon dioxide, which is neces-sary for the plant to photosyn-thesize. Most orchids placed ina windowsill will receive ad-equate air circulation.

FertilizationFertilizer requirements for

orchids depend largely on thetype of plant being grown, andthe type of growing media inwhich the orchid is growing. Agood general rule is to applyfertilizer once a week while theplant is producing new growth.As the new growth begins tomature, decrease fertilization.Discontinue fertilizing entirelywhen the plants becomedormant, or stop producingnew growth. A good practiceis to water at least once amonth with plain water toprevent root burn from over-fertilization.

Specially formulatedorchid fertilizers are availablethat are already diluted. Followthe label directions exactlywhen using orchid fertilizers.Equally balanced fertilizerssuch as 10-10-10 or 12-12-12can also be used, but thesefertilizers must be diluted toone-quarter strength beforeapplication. Orchids planted inbark require higher nitrogenrates than plants in othergrowing medias, so a ratio of

the old growing media andrinse the roots under tepidwater. Before repotting, trimoff any dead roots, dead oryellowed foliage, dead flowerspikes and dead or rottingpsuedobulbs (a thickened stemon some types of orchids thatis used to store water). Replantthe base or the crown of theorchid at the same level it wasgrowing prior to repotting. Toavoid spreading pests anddisease, use a clean workplace,sterile pots, sterile growingmedia and never transfer soilfrom one plant to another.

ContainersDrainage is one of the

most important factors toconsider when selectingcontainers for your orchids.Containers designed especiallyfor orchids have slits down theside for added drainage (Figure2). Some containers havedrainage holes in the bottomof the pot. If these holes aretoo small, they can be en-larged. Clay and plastic are themost popular materials for

20-10-10 or 30-10-10 fertilizeris recommended.

Growing MediaDrainage and aeration are

the two most important fac-tors to consider when choos-ing a growing mix. Specialblended media can be pur-chased at most retail gardencenters for growing orchids.These mixes contain fir bark,peat moss and either perlite orvermiculite. Many orchidgrowers prefer mixing theirown growing mix. There areseveral types of growing mediato choose from, such as treefern, redwood bark, cork,sphagnum peat moss, Os-munda, charcoal, Rockwool,polystyrene foam, rock cultureand sand. The growing mediaused is a personal preference,depending upon growingconditions and environmentalfactors of the grower.

RepottingMost orchids should be

repotted every one to twoyears, although some varietiescan go years withoutrepotting. Timing isthe most criticalelement in repottingorchids. If orchids arenot repotted at thecorrect time, floweringmay not occur until thenext year. Nearly all repottingshould be done betweenFebruary and June. This is thetime when most orchidsproduce new growth and newroots. This usually occurs justafter the plant flowers. (Plantsthat grow actively year roundcan be repotted anytime.)

While the plant is out ofthe container, clean away all of

Figure 2. Orchid container withside slits for added drainage.

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orchid containers. Whenchoosing a container, considerwhat type of orchid you aregrowing and the growingenvironment. Plants in plasticpots are more susceptible toroot rot, so they should beallowed to dry out betweenwaterings. Plants in clay potswill dry out quicker and willrequire more frequentwaterings. Clay pots breathebetter than plastic, which isgood for plants that preferwell-aerated soils, such asCattleya orchids.

Pests andDiseases

The presence of pests ordisease on orchids is anindication that something iswrong with the orchid’s envi-ronment. Perhaps the plantsare placed too close together,preventing adequate air move-ment, or dead leaves and otherplant debris are littering thearea. Plant stress may also leadto pests and diseases. Theplants may be stressed fromimproper watering, over-fertilization, low humidity,incorrect potting mix, lack oflight or extreme temperaturechanges. These factors shouldbe considered when a pest ordisease is identified andcorrected to prevent furtherproblems. For assistance inidentifying and controllingpests and diseases, contactyour county Extension agent.

InsectsInsects do not present

significant problems in grow-ing orchids. The most commoninsect pests are mealybugs,

scale, aphids, thrips, spidermites, fungus gnats, slugs andsnails. If an infestation isspotted early, the insects canbe hand picked off the plant. Acotton swab dipped in rubbingalcohol can also be effective.Horticultural oils and insecti-cidal soaps are effectiveagainst larger infestations.More potent chemical insecti-cides should be used as a lastresort, as they are often veryexpensive, they may killbeneficial insects and they candamage many other orchidspecies. Be sure to follow labelinstructions when using anypesticide.

Fungal andBacterial Disease

Fungal diseases areusually easy to control.Phytophthora root rot andPythium root rot are amongthe most common fungaldiseases of orchids. Botrytisblight is a common fungaldisease that causes discolora-tion of the flowers. Fungaldiseases can be identified bybrown-to-black, ringed spotson foliage. The best way tocontrol disease is by preven-tion. Keep the growing areafree of plant debris, avoidwetting the foliage and elimi-nate standing water. When adisease is present, remove anddestroy the effective foliage.Fungicides may be used as alast resort, but as with anyother potent chemical pesti-cide, be sure to follow labelinstructions.

Soft, black, water-soakedspots on the foliage indicatebacterial diseases. Bacterialdiseases cannot be cured withfungicides; therefore, plants

with bacterial diseases shouldbe destroyed.

VirusesUnfortunately, viruses are

very difficult to identify. Themost common symptoms aredeformed flowers, streakingfoliage, veinal discoloration,yellowing, stunted growth anddeath. Viruses cannot becured. Any orchid with a virusshould be destroyed to pre-vent its spread to other plants.Viruses may be prevented bykeeping the growing areaclean, using sterile pots andgrowing media, sterilizing allpruning instruments andkeeping your plants free ofaphids, since they can transmitviruses.

Pest ControlIntegrated Pest Manage-

ment (IPM) is a programdesigned to minimize (noteliminate) the use of chemicalcontrols in the environment.IPM is not only a benefit to theenvironment, but it is alsoeconomically beneficial, sincechemical pesticides and fungi-cides are often expensive. Thesuccess of IPM relies on fre-quent monitoring and inspec-tion of plants. By carefullymonitoring and inspecting,most pests and diseases canbe identified at a manageablestage; therefore, the need forpotent chemicals is eliminatedor reduced. Once a pest ordisease has been identified,the first response is to hand-pick the insect, or cut awaydiseased tissue. Traps, soapsand oils are the second alter-native. The last resort recom-mended would be the use ofbotanical pesticides/ fungi-

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cides and then chemicalpesticides/fungicides.

Easy-to-GrowOrchids

The most commonmistake beginning orchidgrowers make when choosingtheir first orchid is to pur-chase the showiest plant.Unfortunately, the showiestorchids are often the mostdifficult to grow. Four of themost popular orchids areCattleyas, Phalaenopsis,Paphiopedilums and Oncidi-ums. These orchids are notonly beautiful, but they areamong the easiest to grow.

CattleyaCattleya (CAT-lee-uh), or

Corsage Orchid, is the mostcommonly grown orchid in thehome (Figure 3). These epi-

phytic plants originate fromMexico to Brazil, where theyare often found growing ontrees. They come in a widearray of colors ranging fromlavender to white, red, yellow,orange, green and blue. Cattle-yas, or “catts,” as they aresometimes called, are oftenfragrant. Catts require brightlight and some sun to flower.An east or west window isideal, or a slightly shadedsouth window can be used.Artificial lights may also beused. Four 40-watt fluorescentbulbs and two incandescent40-watt bulbs placed 8 inchesabove the plants will providesufficient light. Dark green,limp foliage or poor floweringindicates insufficient light.Catts require a 15 to 20degree difference in night andday temperature. Day tem-peratures ranging from 70-85F with night temperaturesranging from 55-66F arerecommended. Cattleyaorchids possess a psuedobulbthat stores water, so theymust be allowed to dry be-tween waterings. They need50 to 60 percent humidity inthe home. Place the plants ontrays of moistened gravel oruse a humidifier to increasethe humidity. Catts should befertilized weekly with a one-

quarter to one-halfdiluted 10-10-10 or 12-12-12 fertilizer. RepotCattleyas every two to

three years in the spring.Select a container that is

slightly larger than the rootsystem so the plant can

grow without repotting foranother two to three years.Good aeration and drainageare essential to successfullygrowing Cattleyas.

PhalaenopsisPhalaenopsis (Fal-en-OP-

siss), or Moth Orchid, is themost popular and one of theeasiest plants for beginners(Figure 4). Most of the 44species in this genus originatefrom the Philippines. Theyrange in color from white,pink, yellow and red to green.They may also be striped orspotted. Phalaenopsis, alsocalled phals, send up long,arching sprays that maycontain as many as 20 to 30blooms. They are long-bloom-ing plants, sometimes bloom-ing for up to four months.Keep phals flowering longerby cutting the spike back tothe second or third node afterthe plant has finished bloom-ing. The plant will probablyproduce a lateral spike withmore flowers from this node.Phals make excellent cutflowers also, lasting up to oneweek in water.

Phals are low-light plants(1000-1,500 foot candles).Phals will sunburn if placed ina south or west-facing window,so placing them in an east-facing window is ideal. If awindow does not provideadequate light, artificial light-ing can be used. This is accom-plished by placing four 40-watt fluorescent bulbs and two40-watt incandescent bulbs 8inches above the plant, andsetting a timer for 14 hoursper day. If the foliage becomesdark green and limp, theplants require more light.Figure 3. Cattleya or Corsage Orchid.

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Phals require 70-85F daytemperatures and no less than60F nighttime winter tempera-tures. A potting mix consistingof 60 percent medium fir bark,20 percent perlite and 20percent chopped sphagnummoss is recommended. A one-quarter, diluted 10-10-10 or12-12-12 fertilizer should beapplied weekly. Phals needabout 60 to 70 percent humid-ity. In the home, place orchidson a tray of gravel filled withwater, or a humidifier can beplaced near the plants. Phalsprefer an evenly moist soil,and they are sensitive todrying out. Repot Phalaenopsisevery one to two years in latespring or after the mainflowering season, and selectcontainers that match the rootsize, not the plant size.

PaphiopedilumPaphiopedilum (paf-ee-oh-

PED-ih-lum), or Slipper Orchid,is also an excellent choice forthe beginner (Figure 5). Themost unusual, yet beautiful

flowers in the orchidfamily can be found inthis genus of nearly 60species. They originate

within a range fromNorthern India to Southern

China and Southeast Asia andthe Philippines.Paphiopedilums, or paphs,range in color from white togreen, yellow, brown, pink andred to almost black. Theflowers are often mottled withspots, stripes, hairs and otherstrange growths. The flowersconsist of a pouch-like sacwith one large, showy sepal atthe top. In some species, thefoliage is beautifully mottled.

Paphs, like Phalaenopsis,are low-light plants (1,500 footcandles). As with Phalaenopsisorchids, four 40-watt fluores-cent bulbs and two 40-wattincandescent bulbs placed 8inches above the plant, andsetting a timer for 14 hoursper day can be used to addsufficient light. Generally,mottle-leaved Paphiopedilumsare warm-growing plants,preferring temperatures in the80s during the day and in the60s at night. Plain-leavedpaphs prefer cooler tempera-tures, low 80s to high 70sduring the day, and 50s atnight. Nighttime wintertemperatures shouldrange from 55-60F.Paphs require ahumidity range of 60to 70 percent. Inthe home, placethe plants ona tray

of gravel filled with water, oruse a humidifier to increasethe humidity. Paphs should bewatered thoroughly, and theyshould never be allowed to dryout. Paphs should be grown innarrow, deep plastic contain-ers. A growing mix consistingof 50 percent medium-to-finefir bark, 25 percent coarsequartz sand and an equalamount of course perlite andmilled leaf mold or choppedsphagnum moss. Fertilizeweekly with one-quarterstrength 10-10-10 or 12-12-12.Paphs should be flushed withplain water monthly.Paphiopedilums can berepotted anytime of year, andthey should be repotted everyone to two years.

OncidiumsOncidium (on-SID-ee-um),

or Dancing Lady Orchids aremore difficult to grow thanPhalaenopsis, Paphiopedilumor Cattleya orchids, but theirabundant sprays of yellow

Figure 4. Phalaenopsis orMoth Orchid.

Figure 5. Paphiopedium orSlipper Orchid.

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flowers make them worth theeffort (Figure 6). Oncidiumsare becoming increasinglypopular as new and easy-to-grow hybrids are developed.Some of the new hybridsinclude Oncidium GrowerRamsey, Oncidium Sweet Sugarand Oncidium Taka. The genusOncidium includes about 600species of epiphytic plantsthat are native to the NewWorld Tropics.

Oncidiums are high-lightorchids, requiring more than2500 foot candles. MostOncidiums perform best withone to several hours of sun-light daily, but plants withthick leaves can tolerate morelight than those with thinnerleaves. A bright south-facingwindow is ideal for theseplants. To grow Oncidiumsunder artificial light, placefour 40-watt fluorescent tubessupplemented with incandes-cent lights 6-12 inches abovethe plant. Metal halide andsodium-vapor bulbs can alsobe used, but they should beplaced farther away from theplant. They prefer daytimetemperatures in the 80s.Nighttime winter tempera-tures should be a minimum of55F. Oncidiums require lesshumidity than many otherorchids, ranging from 30 to60 percent. Humidity levels inthe home can be increased byplacing the plants on water-filled trays of gravel, or byplacing a humidifier near theplant. Plants with thick, fleshyleaves need less frequentwatering than those with thinleaves. All Oncidiums shouldbe allowed to dry betweenwatering. Thick-leaved Oncidi-ums can be grown on slabs of

cork bark or tree fern, or inpots filled with course materi-als such as charcoal. Oncidi-ums in a bark-based pottingmedium should be fertilizedtwice a month with a one-quarter strength diluted 30-10-10 fertilizer. For plants inother growing media, fertilizewith a 20-20-20 fertilizer.Repot Oncidiums in the springor when new growth is one-half mature.

Buyingan Orchid

Before buying an orchid,inspect the plant carefully for

any signs of pests and dis-eases. A healthy orchid willhave medium-green leaves,new growth and white roots.Avoid plants that seem sick ordying, since they may beinfested with pests or diseasesthat can be transmitted toother orchids or houseplants.Orchids are generally pricedaccording to their size. Beaware that seedling orchidsmay not bloom for severalyears, so you may want topurchase a larger plant thatwill bloom sooner.

Figure 6. Oncidium or Dancing Lady Orchid.

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SourcesOrchids can be purchased at retail garden centers, mass merchandisers, orchid nurseries and by

mail order catalog. Orchid shows are an excellent source for plants. The plants are usually healthyand vendors are eager to share cultural information and growing tips.

Many excellent reference books on how to grow and care for orchids are available. Local orchidclubs and societies are excellent sources for information. Further information can be obtained from:

The American Orchid Society6000 South Olive Ave.West Palm beach,Florida 33405(561) 585-8666http://orchidweb.org

Memphis Orchid Society, Inc.(4th Sunday, 2 pm, monthly)Adrian Giles6712 Arnett Dr.Millington, TN 38053(901) 872-6546

Orchid Society ofEast Tennessee(2nd Sunday, monthly)Leonard Passmore822 Lizbeth Dr.Johnson City, TN 37604(423) 282-5126

Orchid Societyof Middle Tennessee(3rd Tuesday, monthly)Alan F. BachrachPO Box 50701Nashville, TN 37205(615) 356-6567Fax (615) 865-7499

Smoky Mountain OrchidSocietyAngela Snow3559 Fountain ParkKnoxville, TN 37914(423) 523-5032

Tennessee ValleyOrchid Society(3rd Monday, monthly, 7:30 pm)Robert M. Martin1105 Crownpoint Rd. W.Signal Mountain, TN 37377(423) 886-2104E-mail bobbobbobm@aol.com

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PB1634-1M-3/00 E12-2015-00-083-00

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COOPERATIVE EXTENSION WORK IN AGRICULTURE AND HOME ECONOMICS The University of Tennessee Institute of Agriculture, U.S. Department of Agriculture,

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Charles L. Norman, Dean