The Vanda Alliance, as this varied group of plants is called, is
made up mostly of warmth- and sun-loving orchids with very colorful flowers. Originating
from tropical Asia, they are easily grown in warm climates, where plants are grown outside
in light shade, such as in a lath house. In climates where winters are cold, they are
often summered outside, and grown inside during the winter in a sunny window, or
year-round in a greenhouse.
LIGHT is a crucial factor in producing blooms for some vandaceous plants.
There are three types of vandas: strap-leaf, semi-terete and terete. The first type has
broader, flat leaves, while terete types have round, pencil-shaped leaves. The
semi-teretes are hybrids between the two, with an intermediate shape. Terete types need
full sun, and are best grown in high light climates. In warm, bright climates, you can
grow any type of vanda, outside (if warm) with partial shade for strap-leaf types and
semi-teretes (especially in midday in summer) or inside (when cold) in a bright, south
window. In climates where winters are dull, try strap-leaf types (or
ascocendas); grow
them outside in summer an in full sun inside during the winter. In a greenhouse, give the
plants about 25% to 35% shade, less in winter if dull. Leaves should be a medium green,
not dark green.
TEMPERATURE for most vandas should be warm; a minimum winter night
temperature of 55 degrees F is recommended. Colder spells can be tolerated for a short
time if it is not windy. Optimum temperatures range from 60 degrees F at night to a
maximum of 95 degrees F during the day. Warmer temperatures mean faster growth, which must
be balanced with higher humidity, air movement, and increased water and fertilizer. Days
should be warm and humid for optimum plant growth.
WATER. Vandas generally like lots of water when growing, but must dry
quickly. Because of this, and their extensive root system, they are mostly grown in
slatted wood baskets, or in pots with a coarse potting medium. If warm and sunny, they may
need daily watering, with misting several times a day in dry or hot climates. Water
sparingly in the winter or during cloudy weather, but do not allow plants to shrivel.
HUMIDITY of 80% is ideal. In tropical climates this may be easy to obtain.
Yet in most climates, misting may be necessary during sunny weather. In a greenhouse, this
is easier to provide by wetting down the floor, or using an evaporative cooler. In the
home, place the plants on trays of gravel, partially filled with water. Do not mist the
plants if the leaves will not dry by nighttime. Air movement must be strong.
FERTILIZING. A well-balanced (20-20-20) fertilizer applied full strength
once a week is recommended when warm, or use 1/4 strength every watering. During cool or
cloudy weather, apply fertilizer once every two to four weeks. Use a high-phosphorus
fertilizer (such as 10-30-20) ever third application to promote blooming. A vitamin B1
compound may be beneficial; use it once a month.
POTTING should be done in the spring. Plants in baskets do not need to be
repotted often; leave them unless the potting medium breaks down. Just set the plant, with
the old basket, into a container of water to make the aerial roots more pliable, and then
set plant and basket into a larger basket. For plants in pots, repot in a slightly larger
pot, positioning the plant in the center. Use a coarse medium, whether fir bark, tree
fern, charcoal, etc., and work it around the roots. Keep shaded, humid, but drier at the
roots until new root tips grow. Do not over-pot.
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