Zygopetalum have been successfully grown for more than 100 years.
This popularity has been based on their spectacular flowers plus their ease of cultivation. It is the latter trait that makes them fine candidates for the beginning and advanced orchid grower alike. Few types of orchids are so easy to cultivate. These ornamentals grow best under conditions that are comfortable for both the grower and the plant. Avoiding extremes in temperatures, light and humidity will satisfy the plants. Remember that all aspects of culture are interrelated and must be considered as a group of requirements.
Zygopetalum prefer fairly bright light, though not enough to cause high temperatures. These plants have been long grown out of doors in the Manly Warringah area, making them great companions for Cymbidiums. Observe your plant when determining the proper amount of light rather than merely checking a light meter. Usually a healthy plant that does not flower is receiving inadequate light. The leaves should be light green. If new growths are too green and soft and weak, increase the light. An indication of too much light is a yellow cast to the leaves. In the home, look for a fairly bright location near a north-facing window.
Temperature and Humidity
Zygopetalum are native to the mid-elevation mountain tracts in the Neotropics where moderate conditions are the norm. They prefer day temperatures of 75 to 80 F and nights around 50 to 55 F.
The plants will tolerate much higher temperatures for short periods without damage. Also, they will survive temperatures close to freezing for a short duration (like Cymbidiums), but certainly will not flourish when given this treatment indefinitely. High night temperatures as experienced in the tropics can interfere with flowering. Provide 50 percent relative humidity.
Allowing your growing environment to get stale and stagnant will induce disease. This is an important factor for Zygopetalum because they thrive in a fresh and breezy atmosphere. Remember that orchids in nature experience tremendous air circulation around them.
Watering and Fertilising
The frequency of watering depends on the conditions under which you are growing your plants, and the stage of growth the plants are in. Zygopetalum never want to dry out, nor do they appreciate constantly wet medium. Generally, water the plants once every five to seven days during the growing season, and every seven to nine days during the shorter days of winter. Spring and summer months are the active growing period, and the time to apply a fairly high nitrogen fertiliser (30-10-10) at every other watering. During autumn or winter, either apply the same fertiliser at half strength, or switch to a bloom formula that is high in phosphorous (the second number in the three-number ratio on the label). Fertilisers are salts and may accumulate in the medium, therefore periodically water with plain water to leach them away.
It seems that every grower has a different mix. Fortunately, Zygopetalum adapt to almost any type of mix as long as cultural factors are regulated to compensate. Generally, the mix must be available and economical for it to be practical. We use Werner Diesel's Cymbidium mix or Miscellaneous mix. The most important thing about the mix is that it should be fresh, no older than two years, otherwise the plants may begin to lose their roots. Repot in the early spring following flowering.
Pests and Diseases
Zygopetalum are relatively pest free, although occasionally scale can be a problem. Use an appropriate insecticide at the recommended dosage and read the label regarding follow-up applications. The only fairly common problem with Zygopetalum is black leaf ticking or spotting. This occurs usually in the winter when the temperatures are cooler and air may become stagnant. It is our experience that such spotting is cosmetic and not threatening to the growth habits of the plant.
There is no teacher better than nature itself, so we urge all orchid growers who have not tried the Zygopetalum Alliance to keep an eye out for sturdy plants, and take one home. When the exotic flowers emerge with those wonderful patterns and purple-blue colours, and fragrance, you will be glad you did.