Worm castings can either be obtained by raising worms at home or by purchasing worm castings from a commercial source. It is also possible to buy castings from someone who raises worms fishing or feeding to exotic pets.
Worm tea is made by placing worm castings in a bucket or bin and soaking them in water. Once the water darkens, stir it and pour it into a separate container for use on orchids and other plants.
The best way to use worm tea on orchids is to use it once a month instead of water as part of routine plant care. Saturate the roots with worm tea. Allow the excess to run out the bottom of the pot.