W. Dave Holder is a master gardener. He is a six-time past president of the Alabama Orchid Society and has grown orchids for more than 30 years. He is a volunteer at the Birmingham Botanical Gardens, where he clones orchids and other plants in the Micropropagation Laboratory.

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Cattleya Culture
by W. Dave Holder       #Flowers

Growing Cattleya Orchids


Cattleya trianaei albescens ‘Buga’
Photo by Scott Wilson.

To many people, the beautiful Cattleya is what they think of when the word “orchid” is mentioned — and with good reason. The flowers of the cattleya orchid are large, showy and colorful. Because of their popularity for use in corsages, cattleyas are commonly known as “the corsage orchid.” Named for the English horticulturist William Cattley (1788-1835), Cattleya is among the easiest of the orchid genera to grow. Cattleyas and are available in an extensive color palette, as well as an array of size and form; although contrary to popular belief, there are no black flowering species.

Cattleyas grow naturally from near Central Mexico to Brazil and have been found on several islands in the Caribbean Sea, particularly Trinidad. Approximately 65 species have been found. A few natural hybrids exist, and there are many thousands of “man-made” hybrids.

 

Water


‘Pink Leopard’ cattleya  (C. Lulu x C. Penny Kuroda)
Photo by Elena Gaillard.

The single, most important element of growing cattleya orchids (and just about all houseplants) is proper watering. Cattleyas are epiphytes (a plant that grows on another plant but does not obtain nutrients from it). In nature, cattleyas grow on trees, not in the ground, so the roots dry out soon after watering. To imitate this natural occurrence, let your cattleyas dry out a bit between waterings.

Everyone is equipped with a good moisture meter right on your hand. It is called a finger. The best way to determine if a cattleya needs watering is to stick your finger in the potting media and feel to find out if it is dry. After a while, you will easily be able to determine if your plant needs water just by picking up the pot and feeling its weight. A dry pot is much lighter than a wet pot. A good rule for watering cattleyas is, “When in doubt, don’t.” Wait a day or so and check the moisture again.

When the time comes to water a cattleya, place it in the sink, and let water run through the pot freely. Do not use water that has been through a water softener, because it will seriously damage the roots. Also, do not use water below 50 F; it will thermally shock the plant.

The ideal way to water a cattleya orchid is to collect water in a container the day before and let it sit overnight. This not only eliminates the possibility of temperature shock, it also allows some of the chemicals in municipal water to evaporate. Rainwater works well for watering cattleyas and all other houseplants.

 

Humidity


Native to tropical Central and South America, Cattleya is commonly known as “the corsage orchid” in the U.S. for its popularity in decorative adornments. Photo by Dave Holder

Cattleyas like 50 to 80 percent relative humidity. The average house with central heating but no humidifier may get down to 15 percent humidity in winter. The solution is to place a shallow container of small stones and water under your orchid. Do not let the water level in the container rise high enough to get into the bottom of the orchid pot, as this excess water will rot the roots of your plant.

Misting in the morning can also be useful for raising the relative humidity. Don’t mist at night, as this practice will encourage fungal and bacterial infections. A small relative humidity meter can be purchased for about $10. Both you and your cattleya will be happier with improved relative humidity.

Good, gentle air movement contributes to disease prevention. A small 4-inch fan, available at most electronic supply houses, will provide excellent air flow. Get a light dimmer to slow the fan down and to reduce the noise.

 

Fertilizer

I recommend a 30-10-10 water-soluble fertilizer for cattleyas potted in bark. The reason for the high nitrogen is because the little microbes in the bark are also using nitrogen. If your orchid is potted in an inert material that does not rot, use a balanced fertilizer like 20-20-20. I recommend using the fertilizer at one-half the strength listed on the package. Fertilize every other time you water your orchid.

This is probably the most important rule in growing orchids (and all other plants, too). Never fertilize a dry plant with a water-soluble product. Fertilizing a dry plant can cause serious root damage and even kill your cattleya, especially if the fertilizer is applied full strength. A good rule of orchid culture is to fertilize your plant the day after it has been watered with tap or rain water.


Cattleya walkeriana tipo ‘Sensação’/ ‘Tentação’ Photo by Scott Wilson.

Repotting

Repotting is only necessary when the plant has outgrown its pot or if the potting medium has decomposed. If the cattleya is potted in bark, it will usually take two to three years to break down. It is important to renew the bark occasionally, because rotted bark forms a muck that will hold too much water and rot the roots of your plant. When buying bark to repot a cattleya orchid in, make sure it says “Orchid Bark” or “Orchid Mix” on the container. Most garden shops have a suitable orchid bark mix. The bark used for mulching azaleas will not work with orchids, because it has not had the resins steamed from it.

I have recently been using, with great success, a mix recommended by a local commercial orchid grower. It consists of three parts cypress mulch and one part perlite. This mix will supposedly last up to four years.

Bifoliate (two or more leaves on a growth) cattleyas should be repotted only when the roots are actively growing. This usually occurs in spring, right after flowering. Look for green root tips coming from the base of the plant. Unifoliate (only one leaf on a growth) cattleyas may be repotted anytime.

 

Temperature

Ideal night temperatures are 55 to 60 F and day temperatures, 70 to 85 F. Cattleyas can tolerate a day temperature near 100 F if adequate humidity and air movement are provided. However, new growth will likely be somewhat spindly and flowering may suffer. Likewise, cattleyas can tolerate low temperatures down to near freezing, but growth and flowering will be adversely affected. Almost all tropical plants (especially orchids) benefit from a 10 to 15 degree drop in temperature from day to night.

 

Light


Cattleya percivaliana ‘Remolache’ Photo by Scott Wilson.

Adequate light for cattleyas is the second most important aspect of their culture (after watering). Here, in the Southern U.S. on a sunny day, we get about 10,000 foot-candles of light. In the rainforest, cattleyas live halfway up trees where they get from 3,000 to 5,000 foot-candles a day. I use 50 percent shade cloth on my greenhouse to reduce the light intensity for my cattleyas. Shade cloth is a loosely woven plastic material that is usually black but may be white or green in color. Ideally, the shade cloth should be suspended 6 inches to 1 foot below the glass or plastic covering on the greenhouse. When growing cattleyas indoors, place them near an east or west window. Place a sheer curtain between south-facing windows and your cattleya orchid.

A friend who is into photography can assist you in measuring and adjusting light with a light meter. Fairly inexpensive light meters can also be purchased. It is quite possible to grow cattleyas successfully under artificial lights. The American Orchid Society (AOS) has an excellent book and video on the subject. Growing plants under lights has never been easier than it is now. A timer that will turn lights on at dawn and off at dark can be found in most hardware stores.

Cattleyas and most other orchids are photoperiodic, which means they respond to night length in order to flower. Therefore, a cattleya orchid will grow but never flower if too much light shines on it at night. A good rule to remember is, “If one can see to read newsprint at night, the cattleya is getting too much light.”

In summary, the conditions above are considered ideal. Cattleyas will tolerate a fair amount of deviation from ideal. Some of the finest, prize-winning cattleyas I have ever seen were grown under lights in a basement that was always 70 F. So, go ahead; you, too, can grow cattleya orchids!

Anyone considering growing cattleyas or any other orchids will find it beneficial to join both your local orchid society and the American Orchid Society (AOS). Visit www.orchidweb.org for information about all affiliated local orchid societies and a cornucopia of orchid culture information.

Books About Cattleya Orchids
Orchids For The South - Jack Kramer 
You Can Grow Cattleya Orchids, Revised 2nd Ed. - Mary Noble 
Ortho’s All About Orchids - Elvin McDonald 
Orchid Growing Illustrated - Brian & Wilma Rittershausen


A version of this article appeared in a print edition of State-by-State Gardening July/August 2005.

 

Posted: 04/25/12   RSS | Print

 

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COMMENTS

Ruth Mason McElvain - 05/19/2012

Thank you for your article Dave.  Love the black background for these beauty queens.  Q: Do you use a special perforated orchid pot?  I have inherited an orchid so pot bound in some solid medium I can barely move it, much to my horror: no bark, no pot holes of any sort, side or bottom. There are glossy green leaves but no flowers this season.  I’m looking for a holey orchid pot and orchid medium here in Greenville.  Any advice? (blogger of The Backyard Dirt, Ruth.)

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