I have had bad luck with growing orchids and I wanted to try growing some. Can you offer some advice on how best to proceed?
– Ashley Cabot, Evanston
Moth orchids (Phalaenopsis is the Latin name for the genus, or group of related plants) are among the easiest orchids to care for in a home. They can bloom two to three times per year with flowers that can last for two to six months once they have reached a mature size.
But it’s important to know how to care for them to ensure they flourish.
Many Phalaenopsis orchids are sold potted in sphagnum moss that tends to be tightly packed around the roots to help hold moisture during shipping. The tightly packed moss will tend to retain too much moisture, so it usually is best to repot a newly purchased orchid.
A healthy orchid that will rebloom requires a strong root system. Purchase a fresh, high-quality orchid bark mix that allows the roots to breathe since orchids are technically air plants (epiphytes). The best time to repot moth orchids is right after they have finished flowering. It is also OK to repot them most any time.
Under normal growing conditions, the moth orchid will enter a dormancy period of six to nine months after flowering. The potting medium will break down over the course of about a year, so repot the orchid with fresh medium as needed.
Moth orchids prefer a warm environment of 70 to 80 degrees Fahrenheit during the day and 62 to 65 degrees at night, which is similar to the range in many homes during the winter. Phalaenopsis require moderate light to grow well. Indirect light is ideal, since direct sunlight can burn the leaves. East- and north-facing windows should work well.
Water your moth orchid early in the morning with rain or distilled water as the mix approaches dryness. It is best not to use water softened by a water softener. Watering once every four to seven days should suffice, and the plant should never stand in water. Do not allow it to dry completely out. Feed the moth orchid with a diluted, water-soluble fertilizer each time you water during the growing season. In the winter months, use a diluted fertilizer every third watering.
It can be confusing when deciding how to manage your plant for maximum flower production, since different types of Phalaenopsis orchids respond differently. Gardeners also have different philosophies on the best practice to use.
Since you are just starting out, consider trying the following general course of action:
The flowering spike on most moth orchids turns brown once the spike has finished flowering and should be pruned out. Blooms require energy from the plant, so pruning the spike at this point allows young plants to mature more quickly, and for the next set of flowers to be more spectacular. A moth orchid grown in a consistently warm home environment may need a short period of cold nights in the fall in order to set a bloom spike.
The spike may not die all the way down. When this happens, cut the spike above a node on the stem and allow it to rebloom again as a branch off the flowering spike. This will result in more blooms sooner, but takes energy from the plant, which generally results in smaller blooms. Some Phalaenopsis are best managed this way, as they will bear a few blooms at the end of a spike and continue to bloom sequentially on the same spike for a very long time.
So if you are unsure of what to do, observe the plant and experiment with different techniques. The primary reason to cut spikes off these types of orchids is that they have become too big and unruly.
Tim Johnson is director of horticulture for the Chicago Botanic Garden in Glencoe.
