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Leachate vs. Worm Compost Tea

Keeping the distinction between these terms is actually quite important.


Leachate – The liquid run off (or seepage) that settles in or below the vermicompost or worm castings. Check for accumulated leachate in your vermicomposter frequently (when you feed, or weekly).

Worm tea – The end result of suspending worm castings in highly oxygenated water (brewing).


Leachate can contain phytotoxins (toxins that can harm plants and humans). Some of these toxins are created by bacteria. Every worm bin has good and bad microbes. This is ok of course, as long as the good ones outnumber the bad ones. Some leachate can contain harmful pathogens because it has not been processed through the worms intestinal tract. It should not be used on edible garden plants.

During decomposition, waste releases liquid from the cell structure. This liquid or leachate seeps down through the worm composter into the collection area. The leachate should be drained regularly and if you are getting more than 2-4 ounces of liquid in a week, the composter is probably too wet! We recommend leaving your spigot open with a container underneath to catch the leachate to avoid having it build up in your system. Just keep an eye on it to make sure your container doesn’t overflow!

While leachate can have value as a liquid fertilizer it should be treated with caution. For every story extolling the benefits of using leachate there is one lamenting the problems from having used it. If you decide you want to use the leachate we recommend taking some extra steps.

1. DO NOT use it if it smells bad! Pour it out on an area where it cannot harm living plants like a roadway or driveway.
2. Dilute it ten parts water to one part leachate (10:1)
3. Aerate it with an air pump if available.
4. Use it outdoors on shrubs, ornamentals or flowering plants only. DO NOT use on plants you intend to eat.

Worm Tea

Worm compost tea is known mostly for its ability to boost microbiological activity in soil by adding bacteria, fungi, acinomycetes, and protozoa to the soil. It is brewed by either soaking a porous bag full of worm castings in water or simply dumping the castings into a container of clean chemical free water. Molasses (a food source) is then added to the water as a catalyst to stimulate growth of the microbes. Then last, an air pumping system is installed to increase an aerobic (oxygenated) environment for the inoculation of the microorganisms.

Worm tea is beneficial in so many ways. The microbes delivered in worm tea help plants by out-competing anaerobic and other pathogenic organisms and by occupying infection sites on plants’ root and leaf surfaces.

The purpose behind creating worm tea is to speed up the growth rate of microbes such as bacteria, fungi, protozoa, and nematodes, and to multiply their numbers exponentially. One reason for applying the tea to your plants is that it is absorbed more rapidly by the plant than castings, which are released over time.

When you spray or pour the tea on the soil not only are you feeding the plant, but you increase the number of beneficial microbes in the soil, thus crowding out the bad. It has been proven that the tea, along with the castings, can significantly increase plant growth, as well as crop yields, in the short term (a season) and especially the long term over a period of seasons.

Along with these great benefits come a boost in the plant’s own immune system to be able to resist parasites like the infamous aphid, tomato cyst eelworm, and root knot nematodes. Plants produce certain hormones (like the jasmonic hormone) that insects find distasteful so they are repelled. Worm tea also helps a plant to resist diseases such as Pythium and Rhizoctonia.

When worm tea is sprayed on leaves and foliage, the bad disease-causing microbes are again outnumbered and cannot populate to the levels of taking over a single plant. The tea also aids the plant in creating the “cuticle”, a waxy layer on top of the epidermis, or plant skin. This waxy surface protects the leaves from severe elements and reduces attacks by certain harmful microorganisms and insects.

Making an organic compost tea involves several important steps 1) choosing the right compost, 2) choosing the right nutrients and 3) brewing and applying tea correctly. Our instructions here are only meant to give you some background to tea making.

The compost used in making tea is like the starter you use in making yoghurt, or bread. The compost inoculates the tea with organisms. Thus, you want the compost you begin with to have a good diversity of beneficial organisms!

Plants differ in their soil preferences. Some need a bacterial-dominated soil, others want a fungal-dominated soil, and still others like a soil that’s somewhere in between.

To make an organic compost with more fungi, mix in larger amounts of cardboard, paper, sawdust, wood shavings and heavy stalk plant material as you prepare the compost. For bacterial dominance, use food waste and green plant waste. Whatever compost you use, be sure it is finished, well-stabilized compost, and that it’s fairly fresh.

Always use only dechlorinated water, rainwater, pond or distilled water.

Brewing nutrients also influence the finished tea. To encourage the development of fungi in the tea, mix two parts humic acids, two parts yucca, saponin or aloe vera and one part fish hydrolyzate or other proteins into the water. For bacterial dominance, you’ll feed one liquid ounce black strap molasses per gallon of tea and and an equal amount of cold-water kelp. For the molasses, you can also substitute brown sugar, honey or maple syrup if you like.

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