                             Vanda Alliance

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 blooming 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 part 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 and 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 are 60 degrees Fat night, and 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) every 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, re~pot in a slightly larger pot,
positioning the plant in the center.  Use a coarse medium, whether fir bark, treefern,
charcoal, etc., and work it around the roots.   Keep shaded, humid but drier at the roots
until new root tips grow.   Do not overpot.