Orchids are often stereotyped as being finicky plants that require the temperature and humidity extremes of a tropical rainforest. Although some orchids do grow under these conditions, most thrive under normal household conditions. In general, there are seven basic cultural requirements for successful culture:
Air Circulation: In nature, orchids receive fresh air and gentle breezes daily. The hobbyist can duplicate this condition using a slow turning fan and avoiding air pollutants such as smoke.
Feeding: All orchids need some sort of nourishment since plain water doesn’t contain many nutrients. The brand name of the fertilizer is not as important as what is contained in the bottle. A formulation that is high in Nitrogen will promote lots of leaves and roots but will do little to encourage flowering. It is better to use either a balanced (N-P-K) or high Phosphorus type which sends the ‘right signals’ to the plant to bloom. It is fine to apply just water while the plant is in bloom. Orchid roots are sensitive so great care must be taken not to burn the root tips by over fertilizing. Always use a dilute concentration such as half strength or less every few weeks. We recommend Grow-More 20-20-20.
Humidity: Most orchids need at least 50% all the time to be happy. It is imperative to measure the humidity with a gauge regularly because as the seasons change so does the water content in the air. Supplemental humidity is easily accomplished using a grated humidity tray or an old fashioned pebble tray. Water evaporates around the plants and should be replenished periodically. For large collections, a small humidifier is required.
Light: Cattleya, Dendrobium, and Oncidium orchids prefer filtered sunlight year round to grow and bloom well. Filtered sunlight is best described as direct sun that has been diffused by window blinds, sheer curtains, or an outside trellis. Paphiopedilums and Phalaenopsis need indirect light, also known as shade. A good indicator of light levels is the leaves themselves. Often, dark green foliage means not enough light while pale green foliage means too much. In general, strive for medium green. An easy test for proper light levels is to touch the leaves and if they are warm, then the plant is getting burned.
Potting media: Most popular orchids are epiphytic which means they grow on trees and require an airy potting mixture. We have found that Cypress bark and sphagnum moss work best for Cattleyas and Oncidiums while Fir bark is preferred by Dendrobiums. Always choose the smallest pot that the roots will fit into and pack the new media. A pot clip is usually anchored across the lip of the pot to insure that the plant will not move. Paphiopedilums like a special mixture that often contains fine coconut chips, charcoal, and expanded rock. Phalaenopsis are happiest in either sphagnum moss or peat moss. Clay pots are preferred for all types except Paphs which are particularly vulnerable if the media dries out. Evaluate each plant after it blooms to determine if repotting is necessary – the pseudo-bulbs are outside the pot, the media has broken down, etc.
Temperature: A good rule of thumb is that if the air temperature is comfortable for you, then it is probably good for the orchids too. In the jungles, the highs can be in the 90’s and the lows around 60. The notable exception occurs with Phals which need a 3 week cooling period of 50 degree F nights in the fall to encourage new flower spikes.
Watering: Thoroughly drench orchids once or twice a week by taking them to the sink or using a hose outside. Successful growers water their plants in the mornings on sunny days to guarantee that the leaves will be dry by nightfall thus minimizing the risk of bacterial or fungal infection.
Pests: Like all tropical plants, orchids can attract unwanted pests such as aphids, mealy bugs, mites, and scale (brown and white). Safe sprays that contain pyrethrum or horticultural oils are effective on the foliage and should be applied once a week for a month. We recommend Earth-tone Insect Control. Keeping orchids off the ground will reduce the chance of getting slugs and snails.