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Growing Zygopetalum Orchids

Zygopetalum orchids are a small but very attractive group of orchid species in white or cream with lilac patterns on the flowers that can be found in shades of green, purple, burgundy, and raspberry. The Zygopetalum orchid's name is derived from the Greek word zygon, which means "yoked petal" and refers to the Zygopetalum flower with its yoke-like growth at the base of the flower lip. There are approximately 18 species of Zygopetalum orchids that are easy to grow but occur naturally in the cool rainforest environment of Central America and South America and with the majority of the Zygopetalum species being found in the rainforests of Brazil.

Zygopelatum Kiwi Dusk
Zygopetalum Kiwi Dusk with the yoke-like growth on the flower lip

Zygopetalum orchids have leathery, strap-like leaves and produce multiple blooms of fragrant, brightly colored flowers. The flowers last for up to 8 weeks and make excellent cut flowers. They like moderate light levels and somewhat more water than Cattleya orchids.

Cultivation

Zygopetalum orchids are quite easy to grow and make excellent companion plants when you have Cymbidium orchids as they have more or less the same requirements as far as conditions such as orchid growing and feeding is concerned. The big difference however, is that the Zygopetalum orchid has blooms all year round.

Temperature and Light

Zygopetalum orchids are generally capable of tolerating temperatures that range from 10° to 30° Celsius (or 50° to 85° Fahrenheit), although they can tolerate a slightly wider temperature range for short periods. They thrive in areas with a day time temperature range of 20° to 26° Celsius (70° to 80° Fahrenheit) and a night time temperature range of 10° to 15° Celsius (50° to 60° Fahrenheit).

In the home, placing Zygopetalum orchid plants in a room with relatively cool temperatures will help guard against dehydration but in the greenhouse, they require some shading to prevent the leaves from overheating. In the home, however, they need bright light in the 3000 to 4000-foot candle range. Light is probably the most important condition Zygopetalum orchid plants require to produce fragrant blooms. Thus, placing them outside under the shade of tall trees during the summer months is very beneficial. Do not place them in full sun, however, or the leaves will burn. For best results do place the Zygopetalum orchid plant in good light, but no direct sunlight. If you need to, make use of 40% shade cloth.

Also, do not place the orchid plants or orchid pots on the ground, for insects and slugs (snails) can enter the orchid pots and damage the orchids. Pot hangers can be used to suspend the orchid plants from tree branches, chains, strong trees, or other structures.

Water and humidity

Zygopetalum orchids love water, especially during the growing season, but like most orchids, they don't like wet feet (i.e., roots soaking in standing water). Thus, when it comes to watering Zygopetalum orchids, it is best to soak the potting mix thoroughly and wait until the surface is almost dry before watering again. On the average this will be once every five to seven days, depending on the nature of the potting mix and on the weather. The leaves should also be misted (i.e., sprayed with water) periodically.

Feeding

Zygopetalum orchids should be given a balanced, water soluble fertilizer like Dyna-Gro about once a month. Though they are hungry feeders do stick to a regime where you provide each Zygopetalum orchid pot with approximately ½ cup of a solution of one teaspoon of fertilizer per gallon of water. It is best to under-fertilize rather than to over-fertilize. With the lower light and drier conditions in the home, orchids cannot use as much fertilizer as they can use in the greenhouse. Some growers prefer to increase the humidity around their Zygopetalum orchids in the home by using trays of wet gravel around or under the plants but always ensure that your potted Zygopetalum orchids do not have wet feet.

Pests and Diseases

True to its companion orchid the Zygopetalum orchid also suffers from the same types of pests and diseases that may befall the Cymbidium orchids. Here is a recap of the Cymbidium diseases and pests, and their cures.

  • Mealybugs: Wash with soapy water or wipe off with alcohol using cotton swab.
  • Red spider mite: Mist the top and underside of the leaves regularly.
  • Scale insects: Scrape off and isolate. In severe cases the infected plants may need to be disposed of.

The Zygopetalum leaves are susceptible to black streaking which is commonly known as ticking. A Zygopetalum orchid stricken with this affliction looks very unsightly and this condition is usually brought on by being cultivated in an overly warm climate. Another problem is the leaf tips turning black or starting to die back. This is usually an indication of a salt buildup in the potting medium. The roots of the Zygopetalum are sensitive to salt buildup and the plant will die if not seen to in time. To wash out excess salts, water the plant and ensure that the water flows freely out of the pot.

Potting mix and Repotting

The essential ingredients for the Zygopetalum orchid potting mix should contain Osmunda, fir tree bark, or even coconut fiber. These will help to keep the plant stable in the pot and allow a free flow of water and air through the pot. A mixture of equal parts of medium-grade bark and perlite can also serve as a potting mix for Zygopetalum orchids. Remember that the potting mix must be slightly acidic and must provide good drainage without drying out too quickly.

Zygopetalum orchid plants should not be allowed to become pot bound and should be repotted every other year after the plant has finished blooming in the spring. Always make sure that the new container in which the Zygopetalum orchids is to be transplanted has enough space to allow for two years growth (based on mature bulb size). The pseudobulbs should rest just at the top of the potting mix and not be buried under the soil.

You can increase your amount of plants by dividing the pseudobulbs when you repot the plants. You can break the Zygopetalum orchid's pseudobulbs into groups of two to three pseudobulbs per division and trim off the old growth and roots before placing them in a big enough pot that will allow two years growth. Remember to spread the roots in the pot and the pseudobulbs should rest at the top of the potting mix.

After repotting, place the orchids in cool, shady area for a few weeks to allow them to establish themselves in the new pot and to encourage new root growth. You should not over water the repotted Zygopetalum plants until they have established themselves in their new pots.