Worm tea is fertilizer made by soaking worm castings in water to extract the valuable nutrients inside. Gardeners who practice vermicomposting can make their own, while others can order castings or prepared tea from gardening stores. This fertilizer can be used on indoor and outdoor plants and is typically low-odor as well as nontoxic. This makes it safe to use on cut flowers and food plants, as well as plants that pets and children may handle.
Gardeners start a batch of worm tea by adding castings to a bucket of water. Some gardeners add molasses to encourage beneficial bacteria, and they may also aerate the mixture. This discourages the growth of harmful, and smelly, anaerobic bacteria. After around 24 hours, the tea should be ready for use. The mixture is typically dark, with minimal smell. It contains a number of essential plant nutrients and minerals, and should be diluted for best effect.
To apply worm tea, gardeners can spray or sprinkle it on their crops; one option is to fit a sprayer onto a hose, allowing the water flowing through the hose to dilute the pure fluid. It can be applied at any time to a variety of crops. One side benefit of worm tea is that it tends to discourage small insects, and will keep plants healthier. Gardeners should use it quickly, as it will lose potency with time.
It is important to make worm tea from completely processed worm casings. The fluid draining from a vermicomposting pile is leachate, not tea. While it can have some beneficial nutrients, it may also contain raw materials and harmful bacteria, and is not suitable for applying to the garden. Gardeners can maintain two compost piles to have one fully finished and worked pile available for use at all times; as they deplete the first pile, they can switch to the second pile and start adding new material to the first pile.
With houseplants, worm tea can add luster to leaves and promote healthy, vigorous growth. The low odor is helpful for enclosed environments, and diluted worm tea is unlikely to cause fertilizer burn. It will also be safe for pets like cats and dogs who may explore houseplants out of curiosity and could become ill from chemical fertilizers. The castings and sediment left over after making a batch of worm tea can be returned to the compost pile or applied directly to the garden to add body and loft to the soil.