Worm ‘Leachate’ vs Worm Tea

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“Hi, Please explain what worm tea is exactly and how to use it. Is it the liquid coming out of the bottom of the bin, or is it made using the compost hanging in a bag in a bucket of water? Regards,” ~ Dewald R.

Hi Dewald –

The liquid coming out of the bottom of a bin is more accurately referred to as ‘leachate’, and definitely is not as desirable (from a gardening standpoint) as actual worm tea (aka castings tea, vermicompost tea, compost tea).

Leachate is produced when excess water is released from decomposing wastes and/or is added directly to the system. Partially decomposed  materials are not nearly as well stabilized as mature composts, and thus can contain a variety of potentially phytotoxic (i.e. they can harm your plants) compounds.

Generally, if you dilute leachate and add it to your garden you will likely see some benefits (especially if your worm bin is quite mature), but again you are better off to make tea using finished vermicompost.

Worm tea can be made simply by suspending a permeable bag of castings/vermicompost into a aerated bucket of water.

Aeration of the mixture can be achieved quite easily using an aquarium air pump. Some people suggest that adding a source of simple sugar (molasses, honey etc) and other amendments can help, since they provide fuel for the ‘good guy’ microbes we want associated with our plants. Others have suggested however that this added sugar can also stimulate the growth of pathogens as well.

Worm tea can be used as a foliar spray and root drench – not only for its growth promoting properties, but also as a means of helping to protect plants from the attack of pathogenic microbes.

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  1. I am raising some African violets that I am running tests on using Leachate. I had one violet that was given to me almost dead I watered it with leachate and at first it came back to life and bloomed. After a month or so the same violet has limp stems and leaves and a white substance on the flowers. I tasted the flowers and they were salty. I tested the soil it had a hi level of salt. I also tested the leachate which also contained high level of salt. The casting and bins are not salty. so can anyone explain the very salty Leachate.

  2. My violets like leachate just once in a while,,a long while. Like every 2 months and then a very weak strength in small amount. Yes they perk up and bloom, but have lost color and strength with too much. Same reaction with other soft plants. Don’t over use on bulbs. They grow too fast and lack strength. I find putting too much casting in the soil also gives too much of a boost to bulbs. so with my plants less is more.

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