Most recommendations are to water only when the plant is completely dry, and to give it a good soaking from the top when it needs it. Indoors, you can place a bucket overtop your Spanish moss and then pour cups full of water over the plant until it's dripping. Light: Tillandsia usneoides requires a lot of light. Don't expose it to very strong sun, avoid full sun in the summer afternoon that will dehydrate the plant soon, unless the relative humidity is high.