Orchids: Care and feeding
by February 2013 issue,
There are about 25,000 different species of orchids, making them one of the largest groups of flowering plants. They are native to many different areas of the world, and most are epiphytic (they get most of their moisture from the air), growing on shaded mountain ledges, clinging to trees and branches, or on the forest floor. Despite their delicate nature, orchids can be easily grown indoors, and they make a lovely Valentine’s Day gift for someone special.
Light levels are key to orchid growing. Orchids do not do well in direct sunlight. However, without sufficient light, they will not bloom. Indirect light or diffused light is best. Many orchid enthusiasts actually measure (in foot-candles) the light levels in a given location and adjust them to accommodate the needs of a given species.
Phalaenopsis can tolerate low light levels (800–1,500 foot-candles is best), such as a south windowsill behind a curtain or blind. Oncidium require 1,500–2,500 foot-candles and can tolerate a south or west window as long as the sun is not directly shining on the plants for an extended period. Grow lights can be used to supplement natural light.
You can also gauge proper light levels by watching the leaves of your orchid. You want them light grass green. If they’re very yellow, they are getting sunburned. If they’re dark emerald green, they are not getting enough light.
Most orchids thrive in a warm environment. To encourage bloom, provide a drop of about 10 degrees at night, especially in autumn and winter. The temperature should not fall below 55 degrees at night, with an ideal average of 60–65 degrees. The daytime temperature can go as high as 95 degrees, with 75–80 degrees ideal.
Nothing kills orchids faster than sitting in a pool of water. Water orchids early in the day, so the roots are dry at night. The growing medium should be kept constantly damp — not overwatered or soggy, and never completely dry. In average conditions, a 6-inch pot would need watering about once a week.
Fertilize your orchids during the blooming season with a 10-20-20 fertilizer. After the blooming season, switch to a 20-20-20 fertilizer. If leaf tips turn brown, cut back on fertilizer. It is better to feed more often with a weak solution. Flush occasionally with plain water to prevent salt buildup.
Humidity and Ventilation
Try to maintain a constant environment of warmth, humidity, and circulation. Orchids love humidity, with an ideal of 70–80 percent. In dry areas, add humidity to the growing environment via a humidity tray. You can make your own by placing pebbles in a saucer and putting the orchid pot on top. Keep the pebbles constantly wet, but never let the water reach over the pebbles and into the pot itself — excessive water can cause fatal root damage.
Good air circulation is also important to reduce the chance of harmful bacterial or fungal disease. However, drastic temperature changes (such as a rush of cold air through an open window or door) can be very harmful to orchids. A small fan nearby can provide optimal air circulation.
Repotting should be done every two years or when the roots start breaking out of the pot. Repot into a plastic pot of large-size fir bark or sphagnum moss, with the potting medium right at the crown of the plant. Fold the roots gently into the potting medium, taking care not to break them. Keep the potting medium loose enough to allow for good drainage, yet firm enough to support the plant.
After repotting, allow a two- to four-week recovery period. During this time, keep your orchid out of the sun, water sparingly and do not fertilize.
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