Worm tea is made from worm excrement, or castings, from worm compost. The castings are diluted with water and oxygen is added to encourage the growth of useful bacteria. The fluid that drains from the bottom of a worm composting bin is not worm tea; it is leached fluid that contains undissolved solids and some potentially harmful bacteria.
Making Worm Tea
Fill 3/4 of a 5-gallon bucket with tap water. Insert an aquarium air pump and bubbler and let the water aerate for two hours. Insert three to five handfuls of worm castings and 1 tbsp. of unsulfured molasses. Let the mixture bubble for 24 to 48 hours.
The molasses encourages the growth of beneficial bacteria.
Straining Worm Tea
If you don't strain your worm tea, it may contain worm eggs. If you use unstrained worm tea on indoor plants, the eggs can turn into worms that will eventually consume all the organic matter in your potting soil.
Strain the liquid through a coffee filter, then dilute it with four parts of water. It is ready to be sprayed onto your plants. Work the remaining solids into your garden soil or return them to the compost pile.
Used as Fertilizer
Apply properly strained, diluted worm tea can with a sprayer. Worm tea is rich in nitrogen and other plant nutrients. You can use it for flowers, shrubs, lawn and other plants. Add a few drops to vases of freshly-cut flowers to make them last longer.
Worm tea is almost completely odorless and is a good organic fertilizer for indoor plants.
Use a mixture of one part tea to five parts of water in hydroponics system.
Insects and Diseases
Spraying worm tea sprayed on plants serves as a natural repellent for aphids, mites, scale and white flies. It also serves a natural fungicide when sprayed on the surface of plants. Spray worm tea on fruit trees suffering from leaf curl and tomatoes suffering from blight.
Chlorine kills micro-organisms; if your water contains chlorine let it sit for one day in direct sunlight.
You can buy inexpensive aquarium aerators at pet supply stores and many garden centers.
Do not spray your plants in direct sun. Water evaporates more quickly than worm tea. If left on the leaves in direct sun, worm tea concentrates the sun's rays much like a magnifying glass and can burn your plants. Add worm tea when you water your plants.