ORIGIN/HABITAT: Burma and Thailand. This orchid has a rather limited distribution in the Shan States of eastern Burma and in the neighboring mountains of northern Thailand at elevations of about 3300 ft. (1000 m).
Veitch (1887-1894) reported that this orchid grows “on trees in a deciduous jungle fully exposed to the sun in the dry season, when the temperature frequently rises to 45C (112F) in the shade and when its leaves are often scorched.” According to Seidenfaden (1988), plants reported as Vanda bensonii from China are actually a dark-colored form of the Vanda brunnea-complex.
LIGHT: 4000-5000 fc. Visitors to the habitat report that plants grow well in almost full sunlight. In the habitat, however, heavy summer cloud cover dramatically reduces light. This suggests that some shading is appropriate
for cultivated plants at midday in summer. Strong air movement is recommended at all times. Long, deep green leaves indicate light levels are too low. Short, pale, yellow-green leaves that do not spread fully open indicate light levels are too high.
TEMPERATURES: Summer days average 78-80F (26-27C), and nights average 65-66F (18-19C), with a diurnal range of 13-14F (7-8C). The warmest days occur in spring during the clear weather at the end of the dry season.
Spring days average 86-89F (30-32C), and nights warm from 53F (12C) at the start of spring to 67F (19C) at the end of the season, and the diurnal range decreases from 35F (19C) early in the season to 19F (11C) at its end.
HUMIDITY: 80-85% in summer and early autumn, dropping rapidly in early winter to 50-60% which lasts until late winter or early spring.
WATER: Rainfall in the habitat is heavy from late spring to early autumn. Averages then decrease fairly rapidly until they are very low in winter and early spring. During the early part of the dry season humidity is high enough so that additional moisture usually is available from dew and late-night mist. But for a month or so in late winter and early spring, conditions are so dry that even this moisture is seldom available. Cultivated plants should be watered heavily while actively growing, but they need much less water starting in late autumn when the new growth matures.
FERTILIZER: 1/4-1/2 recommended strength, applied weekly when plants are actively growing. Many growers use a high-nitrogen fertilizer from spring to midsummer, then switch to one high in phosphates in late summer and
REST PERIOD: Winter days average 76-81F (24-27C), and nights average 48-50F (9-10C), with a diurnal range of 26-33F (14-18C). Rainfall is low in winter, but additional moisture from heavy dew and mist is usually available for most of the dry season. For 1-2 months in late winter or early spring, however, conditions are so dry that even moisture from dew is uncommon. Cultivated plants need less water in winter, but they should not be dry for long periods. Water should probably be reduced even further for a month or so in early spring, however, with only a light misting given if plants show signs of stress. Fertilizer should be reduced or eliminated until new growth starts in spring and heavier watering is resumed.
GROWING MEDIA: Plants are usually grown in hanging pots or slatted wooden baskets filled with a very open, chunky, fast-draining medium. Some are grown with only enough medium, such as charcoal, wine corks, or large cork chips, to anchor the plant until it becomes established. Roots should be allowed to grow and hang down as far as they choose and should not be trimmed to make a plant look neat. Growers indicate that anything more than minimum root trimming may set the plant back 2-3 years. Continuous brisk air movement around the roots is very important.
*Cultural notes from http://www.orchidculture.com/