CONDITIONS These orchids originate in Southern Brazil and grow as terrestrials in sparse woods, on brushy gentle slopes or on grassy plains or meadows near forests at 1300-1700 metres. Summer days average 21-23C to 13-14C at night. Winter averages 8-9C at night. Humidity averages 80% to 75% year round. Rainfall is moderate to heavy from Spring to early Autumn but somewhat drier in late Autumn and Winter. Plants should not be allowed to dry out completely so ensure that over winter, plants do get a limited supply of water. Healthy plants that do not bloom usually have inadequate light. Light green leaves are good, whereas deep green indicate too little light. No sun, now flowers as a rule.
Propagation: Mature plants will need re-potting into new mix every 2 to 3 years. Place the back of the plant to the edge of the pot allowing enough space at the front for the new bulbs to mature and flower. You can divide plants after flowering when there is active new growth. It is suggested that each division should have at least 3 bulbs, preferably 4 to ensure stability and flowering for the next year. You can also strike new plants from backbulbs potted in Sphagnum moss. They will need to be potted up in a finer mix than mature plants once their new growth is maturing and there is a good root system.
Potting Mix: Zygopetalums are usually grown in pots filled with a relative coarse, well drained medium similar to a Cymbidium mix. The root system is extensive and lush so a deep pot is preferred. Repotting should be done just as new root growth is starting, often when new growths are half completed or as soon after flowering as possible.
Watering: As stated previously, these orchids need to be kept moist year round. Lots of watering from Spring to Summer, but be careful not to leave water in the leaf axis on hot sunny days as this will cause the leaves to rot and fungal conditions may become a problem. Never let them dry out completely. Never water during the day when very hot, only early morning or late evening when that thermometer is rising up past 28C. Try to keep water off the leaves in cold weather to avoid unsightly spotting on the leaves.
Fertilizing: A balanced fertilizer mixed at ¼ to ½ recommended strength should be applied weekly during periods of active growth. Many growers use of a bloom booster with lower nitrogen and higher phosphate in Autumn to improve blooming the next season and encourage new growths to harden before Winter. Fertilizer should be reduced or eliminated until water is increased in Spring. Never fertilise a dry plant. Water the day before, then feed it.
Flowering: Most Zygopetalums flower from Spring through to Autumn. They have strong erect spikes that may be up to 100cm long which emerge from the sheathing bracts at the base of the new growth. Blooms are 5cm to 10cm in diameter depending on the species or hybrid. The flowers are waxy and long lasting with a wide range of colours from yellowish greens to purples.
Problems: The usual slugs, snails, scale, aphids and red spider can be present. Treat with a commercial pesticide or insecticide according to the instructions. Overhead Winter watering will always cause problems with unsightly leaf spotting, so be very careful and try not to overhead water.