CULTURE OF CATASETINAE, SCHLECTER
by Harold Hills
The Sub-tribe Catasetinae includes the Genera Catasetum, Clowesia, Cycnoches, Dressleria, and Mormodes. Culture of Dressleria even though once included in the genus Catasetum is different. Do not try to grow Dressleria species using these suggestions.
The plants of Tribe Catasetinae are widespread in lowland tropical areas of South and Central America up to elevations of about 1200-1500 meters. Most of the discussion which follows pertains particularly to Catasetum a genus with 80-120 species. The plants can generally be found growing on trees, tree stumps, or old fence posts. The plants are weedy and tend to be fairly abundant once you find the first plant or plants.
The highly fragrant flowers of the genus Catasetum can be male or female depending on the condition under which they are grown. Female flowers will often be produced under conditions of high light and low moisture. Males are produced in shadier situation of higher moisture. Aluminum foil caps placed over the tip of developing inflorescences seems to insure more male flowers. The male flowers are more attractive and are noted for the way in which the pollinia are fired out of the flowers if the sensitive triggers are touched.
Growing catasetums should be no more difficult than growing your other orchids or house plants which like warm temperatures and lots of light. In their native habitat they generally experience a dry period of several months. During this period the plants lose their leaves and are dormant. When the plants are in the leafless condition, they should be watered only enough to prevent the pseudobulbs from shriveling (once or twice a month maybe less). They can be killed very rapidly by over watering when in a leafless condition. Death seems to happen almost overnight. If in doubt, no leaves, no water, is probably safer. I regularly forced my plants into dormancy by cutting off any remaining leaves in November.
Catasetums will do well in a variety of potting media so long as they are fertilized and watered regularly. To simplify your watering requirements it is probably best to use the potting medium which has been used for your other orchids. Sphagnum moss works well for most people. I have used a mixture of fresh and composted horse manure, and charcoal (1-1-1). Cow or sheep manure mixes work well also. I know one grower who uses "rock wool insulation". Other people use cork or tezontle (crushed volcanic rock) and some people attach the plants to tree fern plaques or driftwood. I think overall that growing the plants in pots is the better method. The plants are not frost hardy and should not be exposed to temperatures below 40 degrees Fahrenheit when in active growth. In parts of Mexico the plants do grow in areas which do receive frost, but the frost is light and rare and the plants are dormant during the times when they might get frost.
When a new growth appears at the base of the pseudobulb, is the time to repot the plant. The plants should be repotted yearly for best growth, but this is not a rigid rule. I have seen plants that have not been repotted for 5 or more years. Remove all but the last 1 or 2 pseudobulbs. I routinely divide my plants to single pseudobulbs. Old roots can be left on and will help anchor the plant in the new potting media. Once the new growth has roots about a half inch long, watering should be resumed on a regular basis. For the average grower the plants can simply be put outside during the warmer months in light shade and watered every other day when it does not rain. If grown in a greenhouse, hanging the plants in the upper part of the greenhouse will generally provide the higher light intensities and temperatures desired. Catasetums are heavy feeders and for optimum growth and flowering they should be fertilized weekly with whatever fertilizer you use for your other plants following package directions. If you are growing other orchids, then the usual fertilizer rated 20-20-20 or 18-18-18 is ideal. Slow release fertilizers such as Procote or Osmocote are also very good and need only be applied once or twice during the growing season. I have produced "huge" pseudobulbs by applying a tablespoon of Osmocote to each pot and then fertilizing weekly in addition.
The "backbulbs" can be use to start additional plants. Remove the old roots and lay the backbulbs down on a bench top or in a flat until a new growth starts at the bottom or sides of the pseudobulb. It may take several months for the new growth to appear on the old bulbs. Simply pot the pseudobulb so that the new growth is at the surface of the potting media. If several growths appear along the sides of the pseudobulb, then it can be laid on the surface of the potting media.
Catasetums are prone to attacks by spider mites. This problem can be avoided to some extent by high humidity and good air circulation. Spraying the plants alternately with Vendex, Pentac, or Avid following the package directions should control the mites. Cygon can also be used to alternate in the spray program particularly if you have scale or mealy bugs. Do not use insecticidal soaps on flower spikes. The new growths and flower spikes are favorite food for slugs and snails. Grasshoppers will eat the flower buds. Regular use of a systemic fungicide seems to help in preventing rot of the new growths.
What is presented here is what has worked for me in a greenhouse devoted mostly to catasetums and related genera. Other people who have success with catasetums grow them differently and the method that works for one often does not work for another. Lots of light, warm growing conditions, regular water and fertilizer are where to start. One thing that most growers will agree on, is that excess moisture when the plants are leafless seems to be the major causes for loss of plants.
The most highly prized species of Catasetum are: C. pileatum and hybrids, C. expansum and hybrids, C. saccatum, C. fimbriatum, C. tenebrosum and C. barbatum. There are many other species You should expect to pay from $20-40.00 for a good clone of C. pileatum, sometimes more. The species of the genus Clowesia in general are desirable. Clowesia rosea is particularly nice and has a very pleasant fragrance. All but one species of Clowesia comes from Mexico and it is difficult to obtain the plants. They are easily grown from seed and seed grown plants are sometimes available. Cycnoches warcewiczii is particularly nice but the 5 inch flowers are small compared to C. chlorochilon. Mormodes are more difficult to maintain in culture and are not recommended except for the serious grower. Dressleria species are very rare and must be grown wetter and cooler along with Phalenopsis or Phaphiopedilums.
Most orchid nurseries dealing with species will generally have some plants for sale. Sherwood Forest Orchids and JEM Orchids generally have good selections. JEM Orchids have produced some very nice awarded hybrids.
Sherwood Forest Orchids, 9360 SW 32 Ct, Ocala, Florida, 34476. Phone/FAX 904 237-5051
JEM Orchids, 6595 Morikami Park Road, Del Ray Beach, Florida 33446. Phone/FAX 407 498-4308
Harold G. Hills, Ph.D.
University of Massechusetts Medical School
55 Lake Avenue North
rev. May 2001