Vermicompost Benefits

Vermicompost is the magical elixir that will make all of your bad gardening habits disappear! It will bring back to life all of your dead houseplants with just a teaspoon of material….OK so hopefully you are picking up on my sarcasm, but YES vermicompost does have many benefits. It’s just not the end all be all of gardening fixes.

Soil Benefits

Most of the benefits vermicompost provides is to the soil itself. Depending on the type of soil you have, the benefits may differ. Some of the general benefits that vermicompost provides are the following:

  • Increase in organic matter – this is sort of a given since vermicompost is organic matter so just by adding it you will be increasing the total amount in the soil
  • Increase in microbial activity – part of what makes vermicompost so great is the large quantity of beneficial microbes see this article from The Atlantic about how these microbes are not just beneficial to plants, but us as well
  • Forms soil aggregates – worm snot (ok mucus…still gross) helps bind soil particles together which helps prevent erosion and increases both airflow and moisture retention

Clay Soils

Vermicompost main benefit for clay soils is improvement of the soil structure. Clay is a very fine particles that have an extremely high surface area. These particles especially when wet clump together and are not easily pulled apart. The air space in clay soils are also limited. Vermicompost helps increase the particle size in the clay soil which increases airflow. It also binds (see soil aggregates above) the soil particles which also leads to increased airflow.

Sandy Soils

Vermicompost main benefit for sandy soils is improved moisture retention. Sand is quite porous and drains very easily (not a bad thing if you are used to clay soil!). This can be a disadvantage during periods of drought. Vermicompost allows the sandy soil to retain moisture longer.

There are way more benefits that vermicompost can provide the soil but a lot of the information is in science speak. Here is a link to 24,900 scientific studies if you want to take a look.

This healthy forest has multiple layers from groundcover to over story trees. This healthy soil provides all the nutrition plants need.

Plant Benefits

Although the soil benefits are really interesting, I think the majority are interested in the effects on plants. Now it should be noted that vermicomposts can vary quite a bit based on how they were made. Manure based vermicompost will be quite different than food waste types. Food waste types can vary greatly too based on the types of scraps provided. In general vermicompost can provide plants benefits through the following:

There are thousands of articles on the benefits vermicompost provides to plants. You can read about benefits without all the science speak here and here.

How to use in the garden

So all these benefits are really great but how on earth can you put it to use? The two main ways vermicompost is used is through a liquid tea or extract and direct application.

Direct Application

A little goes a long way..REALLY! Many of the studies from the links above used vermicompost in rates from 5-40% by volume. There is some evidence that more than 40% and vermicompost can be detrimental to plant growth. Around 10-20% appears to be the sweet spot for most plants.

Seed Germination

In general, seeds have all the nutrition they need to start out with and the soil is just a medium for the roots to hold on to. However, a small amount of vermicompost will help get the small starts off to well…a good start! Only about a tablespoon of vermicompost mixed into the seed starting mix is sufficient.

Transplanting

When transplanting plants into the landscape, you can add about a handful or so into the planting hole. Larger plants such as shrubs and small trees use several handfuls to coat the inside of the planting hole.

Houseplants

Add about a tablespoon once a month or every other month. Remember indoor plants have to rely on the soil in their container only and potting mixes only offer so much nutrition. Also, I have found adding extract to my houseplants has really helped them. I should also mention that I’m really good at killing houseplants…so I need all the help I can get!

Existing or established plants

This is a little harder to determine as the sizes of plants are so varied, but add about 2-3 cups worth around the drip line of the plant. The drip line is where the outer edges of the leaves of the plant are located. So don’t put the vermicompost at the base or trunk of a plant. In fact don’t even put mulch around the base of plants as it can lead to root rot and can kill the bark. This practice is known as volcano mulching and should be avoided, click here for examples. For older, established trees vermicompost isn’t necessary and good luck determining the drip line of a massive oak tree…I should also mention that vermicompost should be covered with mulch or worked into the soil. For these established plants, use a garden fork and rake in the vermicompost into the soil. If left uncovered, the microbes will die off fairly quick as sunlight (UV light) kills the microbes.

Lawns

I would avoid using vermicompost on lawns or at least direct application. By adding vermicompost directly, there is a good chance that the beneficial microbes will be killed off by UV light quite quickly. For lawn application it would be best to mix vermicompost with some other material such as sand so that the microbes can be shielded somewhat from the light. Also, the amount of vermicompost required to cover a lawn is probably not worth the expense. A vermicompost tea or extract is more appropriate for lawns.

Vermicompost Tea and Extract

DO NOT DRINK!!!!

Teas and extracts are similar as both are liquid solutions of vermicompost. The main difference is one takes a long time to make (tea) and the other is well simple (extract). There are other sites that cover this topic but Dr. Elaine Ingham’s methods for making both teas and extracts are the gold standard. Learn about it here and watch a video here. The quick conclusion is that extracts are better for use on the soil and teas are better as a foliar spray. Both contain billions of beneficial microbes that help the both the plants and soil. As mentioned above with lawns, either tea or extract can cover a much larger area than direct application of vermicompost alone.

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