Lighting for Vandas
Our strap-leaf vandas and our ascocendas flourish in bright light but will not tolerate full sun. Pool enclosures and screened-in patios usually provide excellent reason for growing them. They also thrive hung from trees in places where they are shaded from the noonday sun, but will get direct light until 10:00 a.m. or after 3:00 p.m. Plants receiving proper light for growing and blooming should be bright apple green (like a Granny Smith apple). Plants that are yellow are in too bright a spot and plants that are too dark green may not flower. Most vandas bloom twice a year, and the ascocendas can bloom up to six times a year!
Watering for Vandas
These plants love an abundance of water and high humidity particularly when temperatures are high. They enjoy central and south Florida’s rainy season and they should not go without water for more than 2-3 days if the temperature is above 80 degrees. In spring when humidity is low and temperatures are high, they can be watered almost daily. They also profit from occasional misting in hot dry weather. In winter, they require less water and should be watered only when completely dried from the last watering or rain, usually every 2-4 days. Softening or wrinkling of the lower leaves indicates the plant is under-watered. The frequency of watering should be increased if this happens. In all cases the roots should be overall dark green when the watering is over. Usually this is best accomplished with 2 or 3 applications spaced apart by a few minutes. When watering a mixed orchid collection, Vandas should be watered first and then again last.
Fertilizer for Vandas
Vandas and ascocendas are heavy feeders as orchids go. During warm weather when they are in rapid growth, they enjoy weekly applications of Millers or Peters 20-20-20 at a rate of 2 tsp. Per gallon. Beginning in August, many growers switch to 10-30-20 or other bloom booster fertilizers. If you can’t find 10-30-20, you can use 10-30-10 as a substitute. The plants need less fertilizer in winter, but as they continue to grow, they still need to be fed on 2-3 week intervals in cool weather. In March, the regular fertilizer schedule can begin again. In general, under all conditions, Vandas should be fertilized every 5th watering. Furthermore, once a month, we add 1/4 teespoon of SUPERthrive, a concentrated vitamin and hormone solution, to each gallon of fertilize solution.
Problems & Solutions
Vandas and ascocendas have few pests or diseases. Flower spikes and buds are occasionally attacked by thrips. These can be effectively controlled by an application of Orthene Soluble Power, Diazinon WP or Safers Soap is also effective. Spraying for thrips two or three times a year should also control the other major insect pests. Fungus diseases can sometimes be a problem, particularly in late summer at the end of the rainy season. Most growers spray their plants with Manzate, Captan, Truban or Banrot during this period. Some dust Captan or Manzate in the drown of the plant. With good air circulation and when plants are not crowded, however, fungus disease is seldom a problems, as in the greenhouse at Goodwin Orchids. We seldom use chemical controls.
Vandas and ascocendas are happiest when the temperature never falls below 50 degrees. However, they are also among the easiest orchids to grow. Plants protected from cold produce many more flowers and have few insect or disease problems. They can be maintained in attractive wooden baskets for years with repotting occasionally to become truly spectacular specimen plants.
For more detailed information about Vandas and Ascocendas, we recommend the following books: Vandas and Ascocendas and Their Combinations with Other Genera, by Dr. David L. Grove and Vandas: Their Botany, History, and Culture, by Dr. Martin R. Motes.
The above information has been gathered from growing culture tips by Dr. Martin Motes (a foremost leader in vandaceous culture in the United States) and is used with his permission.