The Vanda Alliance is made up mostly of warm and full-sun growing orchids with colourful flowers. Originating in tropical Asia, they are easily grown in warm climates, where plants are cultivated outside in light shade, such as in a greenhouse. In climates where winters are cold, they are often summered outside, and grown with heat during the winter.
Temperature
Temperatures for most vandas should be warm; a minimum night temperature of 12℃ is recommended. Colder spells can be tolerated for a short time if it is not windy. Optimum temperatures are 18℃ at night, and a maximum of 35℃ during the day. Days should be warm and humid for optimum plant growth, 80% humidity is ideal.
Light
Light is a crucial factor in blooming most Vandaceous plants. There are 2 main types: strap-leaved and terete. The first type has broader flat leaves, while terete types have round, pencil-shaped leaves. Terete types need full sun and are best grown in high-light climates. In a greenhouse, give the plants about 25 to 35 percent shade, less in winter if often overcast. Leaves should be a medium green, not dark green. Broader leaved types need more shade, about 50%.
Water
Should be applied copiously when the plants are growing, but the roots must dry quickly. Because of this, and their extensive root system, they are mostly grown in slatted-wood baskets, or in slatted pots with a coarse potting medium. If their situation is warm and sunny, they may need daily watering. Water sparingly in the winter or during cloudy weather.
Fertiliser
Fertilise with a balanced (such as 20-20-20) fertiliser applied full strength once a week during warm weather or use a quarter-strength solution at every watering. During cool or cloudy weather, apply fertiliser once every two to four weeks. Use a high-phosphorus fertiliser (such as 10-30-20) every third application to promote flowering.
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. Set the plant, with the old basket intact, 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 centre. Use a coarse medium, whether fir bar, tree fern or charcoal, and work it around the roots. Keep shaded, humid, but drier at the roots until new root tips grow. Do not overpot.