ALTHOUGH C. warneri is not a difficult species to grow, it does have unique requirements. It is actively growing, for example, during the winter months in the United States when most other Cattleyas are dormant. Because of this, it is sometimes difficult to give it the best growing conditions.
Like most other Cattleyas, C. warneri needs a warm, moist atmosphere when growing. It requires a day temperature of 85° F and this can be difficult to provide in the winter in a greenhouse when the sun is at a low angle and the outside temperature is at or below freezing. This is compounded by the problem that most of the other Cattleya species like cooler, drier conditions in keeping with their dormancy in the winter. Since C. warneri will tolerate less than the best conditions and still produce a satisfactory growth, it can usually be grown with the other Cattleya species if you put it in the warmest and sunniest part of the greenhouse. In the winter, this means you may have to hang it near the glass or roof to give it the heat and sun it needs to grow well.
C. warneri will grow well with less sunlight better than most other Cattleya species and many growers recommend lower light intensity for this species. I have found, however, that if you want the strongest growths and the most flowers, you should give C. warneri as much sun and air as you would the other large-flowered Cattleya species, like Cattleya mossiae, Cattleya trianaei and C. warscewiczii, while it is actively growing.
A well-flowered C. warneri will produce at least four flowers on a spike, and five flowers is not unusual. If you have your C warneri plants hanging near the glass during the winter, you should put them back on the bench as soon as buds appear in the sheath. High temperatures are not desirable after the buds form, and intense sunlight can actually cook the buds in the sheath and kill them. A strong growth will normally produce a double sheath. A weak or late growth will sometimes produce only a single sheath or none.
Like all the Cattleya species, you should water C. warneri thoroughly and then let it dry out thoroughly before watering it again. A continuously wet medium will rot the roots. Repot C. warneri only when it begins sending out a flush of new roots, preferably during the warm summer months. — A.A. Chadwick
Reprinted with the permission of the American Orchid Society. From Orchids, June 2000.