Masdevallia, a genus of some 350 species usually from cool, misty mountains of the New World tropics, is known for its showy flowers with sepals striking in their size, shape, and/or color. Their need for a cool, damp environment makes them an excellent choice for cool, coastal climates.
LIGHT: levels for this group usually are thought of as fairly low; however, some successful growers believe that the best flowerings are produced under higher light levels. Plants can be grown, but not necessarily flowered, in the same light levels as those for ferns – 400 to 1,000 foot-candles. Most growers maintain levels adequate for Phalaenopsis and Paphiopedilum – 1,000 to 1,500 foot-candles. Masdevallias can be kept in light intensities up to 2,500 foot-candles if the growing area can be kept cool. Plants grow well under four-tube fluorescent fixtures and can be summered outside in shade.
TEMPERATURES: should be cool to intermediate; plants will grow slowly and eventually expire if temperatures remain high for long periods of time. Cool evenings help reduce heat stress during the day. Nights of 50 to 55° F are ideal; day temperatures should be 60 to 75° F. Evaporative cooling pads or humidifiers are useful in maintaining these conditions.
WATER: is critical for these plants because they have minimal water storage tissue. Roots should be allowed to become just dry before watering again if drainage is adequate, constantly moist roots are fine.
HUMIDITY: is important for these plants. The ideal range is 60% to 80%. In the home, mist the plants (in the morning only) and set the plants on trays of gravel partially filled with water. In the greenhouse or enclosed growing area, humidity can be increased by misting or wetting down the floors, while evaporative coolers help raise humidity and lower temperatures. If plants are summered outdoors, automatic misters under the benches are recommended.
FERTILIZER: should be applied regularly while plants are actively growing. Applications of 30-10-10 type formulations twice a month are ideal for plants in a bark-based medium. A 20-20-20 type formulation should be used for plants in other media. If weather is dull, applications once a month are sufficient. Some growers use a high phosphorus, 10-30-20 type formulation (bloom booster) as plants approach flowering.
POTTING: is best done in the winter or early spring, before the heat of summer and/or as new roots are produced. Plants must be repotted frequently, every one to two years, to keep the potting mix from decomposing. A find-grade potting medium, such as fine fir bark is often used with plastic pots. Sphagnum moss if also used, especially for establishing plants. The bottom one quarter to one third of the pot should be filled with drainage material, either broken crock, rocks or Styrofoam "peanuts". The plant should be positioned in the pot so that the newest growth is farthest from the edge of the pot, allowing the maximum number of new growths without crowding the pot. Plants growing in many directions may be positioned in the center of the pot. Spread the roots over a cone of potting medium and fill in around the roots with potting medium to the junction of the roots and the plant. Firm the medium around the roots by applying pressure. Keep humidity high and the potting medium slightly dry until new roots form. A vitamin B1 compound may help establish newly potted plants.