How to Make Vermicompost Tea

Worms in a feeding tray with fresh food and bedding material in an outdoor vermicomposter.
Ashley-Belle Burns / Getty Images

If you've set up a worm bin, hopefully, you've been rewarded with a lovely crop of vermicompost or vermicastings. For the record, there is a difference between the two:

  • Vermicompost. This is a combination of worm waste (vermicastings) and the broken down organic matter in the worm bin. It's much like the material you'd end up within a typical compost bin, where the original contents break down over time, but with a bit of worm poo mixed in for extra nutrients.
  • Vermicastings. This refers to the waste produced by the worms. Pure worm poo with no additional organic material. Vermicastings are dark brown (almost black) and look like dark, rich, crumbly soil. They contain plenty of nutrition yet are gentle enough to be used on plants immediately. You can sort the vermicastings from the rest of the contents of your worm bin or you can simply allow the worms to completely break down the contents of a bin. The worms won't survive long once the bin contains pure worm castings, so you'll either want to set up a new bin for them as soon as you can or plan on purchasing new worms.

You can put the vermicompost or vermicastings to use in several ways. You may topdress houseplants with it, or add it to planting holes when transplanting. You might want to add it to your seed starting or potting soil mix to increase the nutrient content. Another great way to put them to use is to make your own all-natural liquid fertilizer with them.

Benefits of Vermicompost Tea

Vermicompost tea provides an easy way to provide a quick bit of nutrition to your plants. By steeping or brewing the vermicompost in water, the nutrients and beneficial microbes can easily be absorbed by the soil and/or taken up into the plant. Vermicompost tea will not burn your plants the way some chemical fertilizers can. It's just a reliable, easy method of fertilizing all types of plants in your home and garden.

Making Vermicompost Tea

There are a few ways you can go about brewing vermicompost tea. The one that will result in the highest amount of beneficial microbes is actively aerated compost tea, which means that you add your vermicompost (in a linen or fine mesh bag) to a bucket of water with an air pump installed. Then, let the air pump continuously aerate the water/vermicompost for at least 24 hours. This is a fantastic method, and many gardeners highly recommend it.

There is another way to make compost tea. This method simply requires you to steep vermicompost in a container of water overnight.

One way to do this is to simply add about 1/4 cup of vermicompost or vermicastings to a gallon of water, then strain the vermicompost by pouring the mixture through a fine sieve or filter.

An even easier way to steep some vermicompost tea is to put 1/4 cup of vermicompost into a paper coffee filter and tie it closed tightly with cotton twine. Then, simply add this to a one-gallon watering can or bucket, fill the can with water, and let it sit overnight. When you're ready to use it, simply toss the bag into the compost pile.

To get some of the benefits of aeration, you can try stirring the mixture every once in a while, but it's not the end of the world if you don't do so. Letting it steep overnight provides you with a light brown vermicompost tea that you can then immediately use on any plant, indoors or out.

When to Feed Plants With Vermicompost Tea

During the active growing season, feed houseplants weekly to every 10 days with this tea, and feed veggies and herbs in your outdoor garden at least once a week with it. You really can't overdo it. You can also put this tea into a spray bottle or hose-end sprayer and give your plants a nice foliar feed with it. Some gardeners swear that issues such as powdery mildew are reduced if you use vermicompost tea in this way.

Vermicompost tea is an easy, effective organic way to feed your plants. No matter which method you go with, your plants will be healthier for it.

Article Sources
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  1. Compost Tea for Plant Health. University of Vermont.