What is worm tea?
Worm tea is one of the very useful by-products of running your own Worm Farm. It should not be confused with the leachate or liquid exudate which accumulates in the bottom tray of your worm farm. Leachate or ‘worm juice’ is basically runoff from unfinished worm castings, this can contain alcohol as a result of fermentation, and can also contain fungal and bacterial plant pathogens. Because of this it is best not to apply leachate from unfinished castings directly to your plants. Leachate can be diluted and applied to the soil, as both worm castings and the liquid leachate are high in nitrogen and phosphates even diluted leachate makes a useful soil tonic and liquid food but should not be applied directly to leaves or in concentrated form as it may harm your plants.
A much more beneficial liquid feed and general plant tonic can be created by making your own Worm Tea. Worm tea is a nutritious plant tonic and liquid food made from finished Worm Castings or ‘Vermicast’. Worm tea is created by providing food and oxygen for beneficial micro-organisms to thrive, returning life and nutrients to your plants and soil. Worm Castings and tea can also help to improve water retention of soil and condition poor sandy soils.
By adding Worm castings to water, and providing oxygen and food we create an environment in which beneficial micro-organisms can thrive and reproduce, creating a soil tonic as well as returning recycled nutrients to your plants and garden. Worm tea can also be used as a Compost starter or activator as it contains the same beneficial soil microbes.
What you will need
Worm castings
- Start with worm castings and or leachate
- An old sock or cotton cloth to put castings in
- Water
- A food source; Molasses is suitable, or any raw sugar product is acceptable
- Other ingredients; Including comfrey or comfrey tea to balance nutrient composition, kelp and seaweed are also excellent additions to balance the nutrient composition of the brew.
- Oxygen- You will need to stir the brew regularly or buy a small aquarium pump and airstone for an automated set up, this will allow you to produce a constant supply of worm tea for your plants.
How to brew worm tea
- Worm castings should be contained in an old sock or cotton cloth to filter any large particles from your worm tea.
- A generous handful of Worm Castings is enough to make about 10L of Worm Tea.
- It is best to use filtered water as the chlorine in tap water can kill some of the beneficial microbes in the worm castings.
- Add the ‘food’ of your choice, simple sugars such as molasses or raw sugar provide a simple source of food for beneficial micro-organisms and other soil life.
- Add oxygen to the brew by stirring at least once or twice a day. This is a very important step as the beneficial microbes in the brew cannot survive without oxygen and it will become stagnant. Stagnant Worm tea provides an environment in which anaerobic microbes will thrive, they are responsible for unpleasant smells and are not as beneficial to soil and plants as aerobic micro-organisms which naturally thrive in soil.
- For a constant supply of worm tea with little maintenance you can invest in a simple aquarium pump and air stone to bubble oxygen through your worm tea constantly as it brews.
- The ideal brewing time is a day or two, however a little more or a little less will still create an excellent Worm tea for use as liquid feed.
How to use worm tea as fertiliser
- Adding a small amount of seaweed fertiliser or comfrey brew will further balance the nutrient levels of your worm tea, making it a more complete fertiliser.
- Remove castings when you are going to use the worm tea, which should be diluted about 1:10 parts worm tea to water.
- Apply to your plants and soil as a foliar spray, liquid feed and general tonic. It is excellent for both container plants and the garden and can be applied quite frequently as it is not as harsh as more concentrated fertilisers, it will actually encourage root growth and will not harm leaves when applied as a foliar feed or spray.
- Suitable for use on all plants, it is one of the best ways to make your own liquid plant tonic and recycle nutrients in the garden.
Video: How to make liquid fertilizer
Further reading
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