PHALAENOPSIS ORCHID CULTURE IN THE HOME
Phalaenopsis orchids are the easiest of the common orchids to grow in the home, giving an unusually impressive display of flowers on a relatively small, attractive plant. The following hints should help you to grow them well under your own conditions.
Temperature: Night temperature should be at least 60 deg. F, with 63 to 65 deg. F even better. Daytime temperatures are not as critical, but temperatures above 90 deg. F may stress the plants unless the humidity is well over 50%.
Humidity: Phalaenopsis plants like relatively high humidity (70% is about ideal) but large plants seem to adapt well to most homes, which are usually much drier. They do appreciate any increase in humidity you can arrange but most of the common techniques, such as growing on a shallow container of pebbles partly covered with water, do not help much. Growing near other green plants which give off water vapor can be useful. Remember that the air from a heating or air conditioning duct is extremely dry, so protect your plants from direct contact with this air. Severely restricting the amount of air movement across your plants will help to preserve the natural humidity given off by the plants. Do not use fans to increase air movement.
Light: The most critical requirement, and one which may limit flowering. Light must be indirect or filtered strongly (direct sunlight may burn the leaves). It is impossible to have too much indirect light, so placing the plant near large area windows facing south, east or west is the best arrangement. In quantitative terms, about 300 to 500 foot-candles of light are required to bloom most phalaenopsis. Plants grown about one foot below a standard fluorescent light will grow and bloom well on 16 hour days. A dark period seems to be required each night.
Watering and Fertilizing: Phalaenopsis roots require air and must not be wet continuously or bacterial rot will develop. Plants must be watered thoroughly by flooding or dipping and then allowed to dry significantly before watering again. Dipping has the advantage that you can dip in the dilute fertilizer solution and minimize waste. The frequency watering will depend on the type of potting medium, its condition, type of pot, humidity and other factors. For most nearly mature or mature plants in fir bark, watering will be required about once a week. As the bark begins to break down it holds water longer and the time between waterings may have to be lengthened a little, or, better yet, the plant should be repotted (see below). A complete 30-10-10 fertilizer used at a dilution of about onequarter teaspoon per gallon of water with each watering is the choice of the best growers. The plants should be thoroughly flushed with plain water about once a month to prevent salt buildup. Misting leaves is beneficial in hot, dry locations but do not mist again until completely dry and never late in the afternoon or evening. Light misting of any aerial roots as often as once or twice a day can help greatly to keep these roots healthy and the plant in good condition.
Potting: Phalaenopsis are more tolerant of repotting than most orchids, and seem to be stimulated into active root growth by the new, drier bark. Repotting your phalaenopsis (every two to three years) before the bark in the root zone breaks down and becomes too wet will assure continued good health. Failure to repot is likely to result in severe damage or death for the plant. When repotting, remove the plant carefully from the pot, trying to damage as few roots as possible (plastic pots are ideal since the roots do not attach to the smooth plastic surface). Carefully remove all the old bark and cut off all dead roots, mainly at the bottom of the plant stem. Any dead or damaged parts of the upper live roots can be trimmed back to live tissue. Choose a pot such that the roots will fit by coiling into the smallest reasonably sized pot, leaving some space between roots for bark particles. Unusually long roots can be shortened, rather than be crowded into the pot. Unless it would leave the plant with too few leaves, any leaf that is below a healthy root can be removed at this time. The plant is now held centered upright in the pot with the lowest leaf slightly below the rim of the pot and bark of the appropriate size is placed in the pot, tapped into place between the roots (the final level being just below the lowest leaf), and firmly pressed to eliminate any voids. All bark used should be soaked in water for several hours and dried in air until the surface is no longer wet to the touch. It must then be used within a few days or it must be soaked again. For long term storage, allow to dry completely and store in a container that allows good air penetration. Freshly repotted plants usually require watering a little more frequently (perhaps every 3 to 5 days) for the first month or two, then resume weekly watering. Note that for well established plants too frequent watering can be harmful and if continued long enough, even fatal, while underwatering rarely does more than set the plant back, recovery being almost always assured by increased watering.
Pests: Insects, and bacterial or fungal infections are the main threats; the latter two are rarely found in home culture as the low humidity discourages these organisms. Avoid water standing on the leaves or in the crown for any length of time (especially at night) and you should have few problems. Scale and wooly aphids (mealy bugs) are the common insect pests if any, but hand removal may control them on a few plants. Commercial insecticides may be used (with appropriate caution) if needed. Three or four treatments spaced about one week apart will usually assure sucess. Be sure to follow label instructions for ornamental plants.
Note about the authors: Helen & Maynard Michel are the proprietors of the pretigious Phalaenopsis House, Orchids Orinda, which is part of the Orchid Ranch complex in Livermore, California. They are both long standing, highly esteemed members of the Orchid Society of California and are accredited A.O.S. judges of the Pacific Central Judging Center, with Helen Michel as a chair person. A customer purchasing a plant from their fine Phalaenopsis house generally recieves comprehensize growing instructions from the Michels. They have a genuine concern that the purchaser is able to sucessfully grow their new orchid.