Worm tea, also known as vermicompost tea or worm casting tea, is an organic liquid fertilizer that is made by steeping worm castings in water. The benefits of worm tea for plants are two-fold: it serves as a potent fertilizer and a natural pesticide.

When compared to time-release fertilization of castings alone, worm tea has a rapid absorption rate, making it an extremely potent fertilizer. The microbial activity in worm castings is 10 to 20 times higher than in soil and organic matter that the worm ingests. This microbial activity refers to the powerful combination of enzymes and good symbiotic bacteria in worm digestive systems that carry over its castings, adding healthy bacteria, fungi, actinomycetes, and protozoa to soil. Worm tea makes soil far richer than it could ever become on its own, and it contains two times more calcium, five times more nitrogen, and seven times more phosphorus and potassium than regular soil. Unlike chemical fertilizers, worm tea will never burn plant roots, no matter how much is applied.

Worm tea is also an effective non-chemical pesticide that works on two levels. First, it promotes a healthy plant immune system so it can produce more of the hormones insects find distasteful, which wards away a number of insects, including aphids, parasitic nematodes, and eelworms. Second, when sprayed on leaves, the tea stimulates growth of a waxy layer atop the leaves called the cuticle, which both protects the plant from the elements and wards away leaf munching insects. Coating leaves with worm tea also promotes growth of good microbes that outnumber disease-causing ones, preventing harmful fungi and diseases.

Various studies have investigated the practical role of worm castings in agricultural production. Subsequent meta-analyses of such studies have confirmed worm castings and tea help increase crop production about 25% in both short and long-term growing periods. Being 100% organic, it can safely be used in organic farming to increase plant and soil health and crop yield.

Overall, worm tea is a natural and effective way to improve soil health, plant growth, and ward off pests and diseases. It can be easily made at home using a watering can or spray bottle, aeration, and dilution with dechlorinated water. By incorporating worm tea into gardening practices, gardeners can enhance the health and vitality of their plants.