The Vanda has a very thick water retentive covering on their roots called velamen. This covering holds enough moisture to supply the plant between watering cycles and is why most Vanda are grown without a typical potting medium. Most frequently Vanda are seen grown with large pieces of charcoal or broken clay pot pieces as the potting medium. Basically this material is for anchoring the plant in the pot and not for water retention. When growing in a material such as that, we recommend watering the Vanda every day, to every other day.
Don’t let this frequency of watering prevent you from growing one of these beautiful plants because where there is a will, there is a way. Some of our wonderful customers report using a moist bath towel placed among the roots and then trailed to lie in a nearby container with water. Being away for several weeks has been successfully accomplished using this method.
The proper method of watering your Vanda is to run water across the roots slowly for a period of time to allow the velamen to soak up the water like a sponge. In some cases it is more convenient to soak the pot in water for several minutes. When the roots of the Vanda are dry they tend to appear somewhat white in color. As the water begins to saturate the velamen it begins to turn slightly green in color. This is your indication that you are watering the Vanda thoroughly and properly. If the Vanda leaves begin to fold into a tight “V” shape, then that is an indication the plant is starting to dehydrate and would need more frequent watering. Never allow your pot to stand in any water as this will cause root rot. Never use softened water on any of your orchids.