What is Vermicompost?

Vermicomposting is the process of creating compost with the aid of earthworms. While all composting relies on microbes to do much of the work, vermicomposting allows worms to come to their assistance.

The worm starts the composting process by ingesting organic matter and breaking it down with digestive enzymes. However, the digestive system of an earthworm is rather inefficient, only absorbing about 5% to 10% of the food the worm eats. This is good news for vermicompost, because the rest of the organic matter, now moistened and considerably broken down, is excreted and offers a rich buffet for hungry microbes.

Note that vermicompost and worm castings are not the the same. Worm castings are simply the excrement of the earthworm. Vermicompost includes worm castings, but also worm bedding, food, and remains in various stages of decomposition, all supporting a vibrant community of microbes.

How Vermicompost is Made

Vermicompost is typically made in a “worm bin” filled with bedding (usually shredded paper) and organic material for the worms to eat. A suitable worm habitat is further created by keeping the bin dark and moist.

Two worm species are typically used:

  • Red wiggler (Eisensia fetida).
  • Red worm (Lumbricus rebellus).

The red wiggler is particularly popular because it is easy to care for and produces castings quickly and efficiently.

Of course, you can theoretically dig up any old earthworms in your backyard to populate the worm bin, but there is no guarantee that you will find effective compost-building species this way. A surefire solution is to order red wigglers online.

Finished vermicompost looks very much like high-quality soil, but it is incredibly rich in microbes.

Feed the Worms

Most kitchen scraps and waste paper products make good worm food. However, you will want to avoid anything that produces a foul odor, especially if your worm bins are indoors. That includes meats, oils, dairy products, onions, garlic, potatoes, and anything in the mustard family, such as broccoli. Also note that worms are not a replacement for the neighborhood recycling facility—they cannot process plastic or aluminum.

Benefits of Vermicompost

  • Quick and easy. Vermicomposting does not require the precision or labor that hot composting requires to turn out a successful batch. And it has a distinct advantage over cold composting methods—it’s quick!
  • Year-round composting. Worm bins can be kept inside in the winter, allowing you to make compost for use first thing in the spring.
  • High in beneficial soil microbes. Microbes thrive where worms work, and they are particularly abundant in worm castings. Adding vermicompost to depleted soils can yield dramatic results in garden health.
  • All the benefits of organic matter. Soil that has been amended with vermicompost will not dry out quite so quickly in the hot summer sun, and it has improved texture and nutrient content. (Note that this is true of all forms of composting.)
  • A good use for kitchen scraps. Well-fed worms will repay you by improving your garden soil, which in turn will bring more (and healthier) produce into your kitchen.

Some Drawbacks

  • Expense. Remember, you will only have reliable results with certain worm species. This means you will likely have to buy worms, adding to your gardening costs. (You will also need to purchase a bin the first time out.)
  • Small quantities. Regular composting methods can produce more compost much quicker than earthworms can. You will want to use your vermicompost selectively to feed the plants that need it the most.

Making the Most of Vermicompost

Vermicompost is equally suited to trees, vegetables, flowers, and potted plants.

Because vermicompost is made in relatively small quantities, gardeners will want to use it wisely. A good rule of thumb is to use it to fuel rapidly growing plants.

The best place to apply vermicompost is around the drip line of the plant. Imagine a circle on the ground around the plant roughly marking its circumference. This circle is called the drip line because, if you were to spray the plant with water, this is where the water would drip off of the leaves. Many hungry roots are waiting just below the drip line. Spread the vermicompost on top of the soil along the drip line.

So will vermicomposting meet your needs? Likely not if you have a large garden. For a small garden (or for a good hands-on science project), however, it can be a quick way to improve poor soil.