What Does an Orchid Need to Survive?

Potting Materials

• Though terrestrial orchids grow in the ground like other flowers, tropical orchids -- the kind often for sale at supermarkets and flower shops -- are epiphytes. This means they grow on a host, such as a tree; in the home, they need tree bark or a similar material to act as their host. University of Vermont Extension horticulturalist Leonard Perry, PhD, recommends fir tree bark, coarse perlite or lava rock. Alternatively, gardeners can attach orchids to outdoor trees or slabs of cork for a more dramatic look.

Light

• Though orchids differ in the details of their light requirements, most need bright but indirect sunlight. This is what they receive in the rain forest, where the sun shines but trees diffuse the light. A heavy beating from the sun leaves orchids dehydrated and sunburned; on the other hand, they need bright light to flower. A bright window is the safest spot for orchids, with a sheer curtain drawn if the sun directly hits them. If orchid leaves turn a dark, rich green, the orchid needs more light; if leaves lighten to a yellow-green color, the orchid is in danger of suffering sunburn.

Humidity

• Orchids appreciate humid environments, with 40 percent to 60 percent humidity preferable, according to University of Hawaii horticulture professor Kent Kobayashi. Gardeners can provide the necessary humidity levels by placing orchid pots near a humidifier or on trays filled with moist gravel. Perhaps the simplest way to increase the humidity is to lightly mist orchid leaves in the morning. Air circulation from a ceiling fan or open window should accompany this humidity whenever possible, as moving air helps prevent fungal diseases, a dangerous side effect of high humidity.

Watering

• Though orchids need less water during their dormant period in the winter, watering once or twice a week is plenty even during the flowering season. The bark should dry out between waterings. Drainage is key; orchids should never sit in their own water. Soggy brown roots -- rather than healthy white roots -- indicate the orchid is basking in too much water. Kobayashi recommends watering by mid-day to give foliage time to dry before nightfall; this prevents rot and fungal diseases.

Fertilizer

• Fertilizer is food for orchids. Fortunately, they don't need to eat every day; twice a month is plenty, though gardeners can safely skip a month without killing their orchids. They differ from other plants in needing a diluted fertilizer, as a full-strength fertilizer can scorch them. A diluted fertilizer with equal amounts of nitrogen, phosphorus and potassium -- such as 18-18-18 -- works for orchids in most potting materials, with the exception of orchids planted in bark, which need a high-nitrogen fertilizer such as 30-10-10. In winter, gardeners can reduce the frequency of fertilizing.