University of Vermont Extension 
Department of Plant and Soil Science

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GROWING ORCHIDS 101

 
Dr. Leonard Perry, Extension Professor
University of Vermont
 
 
Orchids are no more difficult to grow than most other houseplants when their particular growth requirements are met. This is the key to success— make sure that you choose species adapted to your indoor growing conditions.  Or, simply buy an orchid already in bloom to just enjoy now.  With proper care, you can get several weeks of bloom from most orchids.

The beginning grower should consider starting with established plants which should bloom within a year. Seedlings are less expensive but may take up to five years to flower. Natural species may be grown, but the hybrids are often more vigorous and less demanding in their cultural requirements.

Although there are more than 25,000 species growing in climates ranging from the arctic tundra to the tropical rain forest, the orchids most often cultivated are species from tropical climates. They are commonly grouped by cool, intermediate, and warm temperature requirements based on the plants' optimum night requirements (45 to 50 degrees F, 55 to 65 degrees F, and above 65 degrees F, respectively). For warm homes, consider the Dendrobium, moth orchid (Phalaenopsis), or Vanda orchids.  The moth orchids grow under similar conditions to African violets, making them one of the best choices for growing indoors.

Some orchids may not bloom if the nighttime and daytime temperatures are the same. Consistently warm temperatures are good for vegetative growth, but may suppress flower development. A 10 to 15 degree reduction in the night temperature for two weeks in the fall or spring is needed to initiate flower development on these species.

Just because orchids may be tropical doesn’t necessarily mean they come from rain forests.  These species need much more humidity than found in most of our heated homes during winter.  Some that come from areas with seasonal dry periods, and so are good in homes with low humidity, include dendrobiums, oncidiums, and the corsage orchid (Cattleya).  Yet dry air may result in failure of flower buds to open and death of orchids in extreme cases. A relative humidity of 60 percent will alleviate the problem. Using a humidifier near plants, or placing them on a tray of pebbles, kept moist, will help most any orchid in dry indoors.   

Light is often a factor limiting the growth and flowering of orchids. Most orchids require relatively high light intensities and should be grown in an east or south window. However, a few such as moth orchids will grow well under low intensity fluorescent lights. If there is too little light, the leaves become a deep, lush green. With too much light, the leaves turn yellow-green.  For proper flowering, the leaves should have only a slight yellow tint.

Orchids vary in their water requirements. Many tropical orchids are epiphytes, growing on the side of trees, and will not do well if their roots stay wet. Epiphytes should be grown in a very porous potting medium such as coarse bark or lava rock. Terrestrial types rooted in soil, such as one of my favorites with its attractive leaves-- the Jewel orchid (Ludisia)-- require a well-drained, finer textured growth medium. Nutrients must be provided in dilute concentrations when orchids are grown on inert media. Moderate air circulation is required for best growth.

Watering frequency depends on the medium in which they are potted. Most orchids cannot survive prolonged drought and should be watered often. However, some require a "dry season" of six to eight weeks to flower, during which watering is reduced but not stopped. This must occur immediately after maturation of the current season's growth.
 
Orchids are affected by many of the same pests and diseases as other houseplants. Insects such as mealybugs, scales, and aphids can be controlled with the proper insecticide—there are several natural-based ones as well as simple controls such as soapy water. Good cultural practices and the purchase of healthy plants will reduce the chance of disease, although most fungal and bacterial diseases may need control using commercially available products.

Specific orchid needs may be found on the plant label, from knowledgeable store personnel at full service garden stores, or from books and online.  Or visit the American Orchid Society website (www.aos.org) if you want to learn more, find local societies, discover resources, or to pursue growing orchids as a hobby.
   

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