This is the big question that keeps coming up in forums, on Reddit and various Facebook groups.
- What do I do with the run-off from my worm bin?
- Isn’t that the Worm Tea that we’ve all heard so much about?
- Do worms actually wee?
Many people believe that the runoff is the worm tea that we’ve all heard about. This is incorrect and can be dangerous!
To start with, worms have neither kidneys or a bladder, so it’s not worm pee.
The runoff in the reservoir is moisture that has collected and drained through the worm bin. Leachate is the result of the decomposition of the organic waste that’s fed to your worms. It may contain phytotoxins (that can harm plants AND humans) and are created by bacteria that aid the decomposition process. This waste liquid is being released from the cell structure of the organic waste as it decomposes.
Every worm bin has a mix of good and bad microbes and as long as the good outnumber the bad, everything is okay. The danger with leachate is that it hasn’t been processed through the worm’s intestinal tract and can contain pathogens.
Leachate should NOT be used on plants that you intend to eat.
Just to be on the safe side.
The Gentleman Vermiculturist leaves the spigot open on his Worm Cafe. If there are more than 2-4 ounces of liquid in a week, the worm farm is probably too wet. Make sure you keep a container under the open spigot and check it regularly to make sure the collected leachate doesn’t overflow.
Well, does it have value as a fertilizer or not?
The short answer is sort of. While it can have value as a liquid fertiliser, it should be treated with caution. There are as many good stories about using it as there are bad. Just take some precautionary steps before using the leachate in your garden.
- If it smells BAD just get rid of it. Pour it out somewhere it can’t harm living plants, like a driveway.
- Dilute it heavily before using it in the garden. Ten parts water to one part leachate seems to be the common recommendation.
- Aerate it for twenty-four hours with an air pump or aquarium bubbler
- Use it outdoors on shrubs, ornamentals or flowering plants only. DO NOT use on plants you intend to eat.
So how do I get Worm Tea (and what is it really)?
Worm tea (like compost tea) works by boosting microbiological activity in the soil as the bacteria, fungi, actinomycetes, and protozoa in the worm tea are introduced. 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.
You brew 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 is then added to the water. This works as a food source and as a catalyst to stimulate the growth of the microbes. The molasses can be replaced by brown sugar, honey or maple syrup if you like.
Lastly, install an air pumping system to increase the oxygen in the environment for the inoculation of the microorganisms.
Worm tea is so amazing because the brewing process creates an incubator for microbes such as bacteria, fungi, protozoa, and nematodes to massively grow their numbers. The resulting worm tea that you apply to your garden is also absorbed more rapidly than worm castings alone, which are more a time release fertiliser.
Adding worm tea to the garden is not just feeding the plants, but increasing the number of beneficial bacteria in the soil. The beneficial bacteria should aggressively compete and crowd out the bad. There is a heap of research out there that proves the tea and the worm casting 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. 
Worm tea will also improve a plant’s immune system. This makes them more resistant to parasites and disease. It will also aid the plants to produce hormones (like the jasmonic hormone) that insects are driven away from.
When applied to a plant’s leaves and foliage, disease-causing microbes are outnumbered and cannot populate to the levels of taking over a single plant. The worm 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.
Worm tea is not hard to make, and evidence shows it will boost crop yields and the resilience of your garden!
I’m interested to hear how you go with your brew of worm tea in the comments below.
 David Murphy, Organic Growing with Worms (this should be mandatory reading for anyone considering setting up a worm farm).