“Fresh earthworm castings contain more organic material – nitrogen, calcium, magnesium, phosphorus and potassium – than soil itself,” according to Texas Agrilife Extension Service. Worm castings and the tea you make from them also ward off root-knot nematodes – a parasitic creature that causes deformed roots and drains nutrients out of plants. Plants like strawberries, that tend to attract fungal spores, will also benefit. Castings contain anti-fungal chemicals that help kill the spores of black spot and powdery mildew.
Making simple worm tea is really nothing more than steeping – much like making any other tea you would drink yourself. It is very easy and it is good for your plants too. In steeping, water is added to the earthworm castings to simply extract the microbes from the castings into the water. The resulting liquid solution is then applied to plants or soil in various ways. Many bottled teas you see on the shelf use this method. To make your own, just take a bunch of worm castings and put them in the bottom 1/3 of a bucket. Fill the rest of the bucket with rain water or non-chlorinated water (or tap water left out in the sunlight for 24 hours if you must). Let the mixture steep for 24 hours. Strain out the solids, dilute with water on a 1:1 ratio, and apply directly to you plants or soil.
It's good stuff. And not 'worm wee' as many like to call it. Worms don't 'wee'. Put the solids into the compost or into the garden. Nothing goes to waste with worms.