Vermicomposting is For the Worms!

Posted on: October 19, 2021
Photo by sippakorn yamkasikorn on Unsplash

It is hard to believe but our food waste and other organic materials such as paper and yard trimmings equate to nearly 55% of our total waste with food making up 20-30% of this total.  When these items are in our landfills, they break down and create a material called leachate, which is toxic and can pollute groundwater, surface water, and soil. Vermicomposting, a process that relies on earthworms and microorganisms to break down organic matter and transform it into a product that can be used as a valuable soil amendment and source of plant nutrients, can help homeowners with their gardening efforts but also keeps organic materials from causing problems in the landfill!

Vermicomposting is a way to get earthworms to work for you in a more organized way. You can become a worm farmer easily. North Carolina State University Extension is a leader in vermicomposting. Rhonda Sherman with North Carolina Extension, states that you need 4 items to begin worm farming.

  1. Worm Bin – You can purchase this through many different garden centers and websites. You can even make this on your own. If you choose to make your own bin, make sure that it has a tight-fitting lid and is a dark color. The bin size depends on the number of food discards produced by your household. According to North Carolina State University, “The general rule of thumb is one square foot of surface area for each pound of food discards generated per week. So, if your household creates two pounds of food scraps weekly, you will need a 2-foot by 1-foot worm bin that is 8 to 20 inches deep.” To access plans simply search on the internet for, DIY worm bin.
  2. Bedding – Bedding is needed to provide a good living environment for the worms. Bedding should be a material that is nontoxic, holds moisture, and allows air circulation. Items to use could be, shredded paper, newspapers, paper bags, office paper, cardboard, decaying leaves, or coir (coconut fiber). Glossy paper or magazines should not be used.

The bedding should be soaked for 5 to 10 minutes in a bucket of water and then should be wrung out. The bedding should be damp but not soaking wet. Worms should have 6 to 8 inches of bedding or at least half the depth of the worm bin.

  1. Worms – It is not as simple as digging worms from a yard or garden. Out of the 9,000 worms, only 7 species are known for use in vermicomposting. Of those, the Red Wiggler (Eisenia fetida) is the type of worm that is used most often with home composting systems. You can buy red wigglers from worm growers found online but be sure to shop around because prices do vary widely.

Once you receive the worms, worms should be placed on top of the bedding in the bin. The worms will immediately start to tunnel under the bedding to avoid the light. If you notice worms outside the bin, place the bin in a well-lit area for a couple of days to help the worms get acclimated to the bin.   

  1. Food Scraps – After a few days, worms should be ready to have some food scraps added to the bin. Items like vegetables, fruits, crushed eggshells, coffee grounds, shredded paper, shredded garden debris are acceptable. Meat items including fish should never be added to the bin. Other items that should not be added are pet/human manure, fat, citrus, tobacco, or onions, and garlic. Once scrapes are added, cover them with 1 to 2 inches of bedding to prevent fruit flies.

Harvesting compost over time is why you vermicompost to begin! It is the valuable mixture of earthworm castings and decomposed bedding and food scraps that will help your plants thrive. There are several methods that are documented by Rhonda Sherman, Extension Solid Waste Specialist with North Carolina Extension:

  1. Sideways Separation - To do this you feed the earthworms on only 1 side of the bin to harvest the vermicompost from the other side.
  2. Light Separation - Empty all contents of the worm bin onto something like a plastic shower curtain in the light. Wait 5 minutes and scrape off the top layer of vermicompost. Continue to do this until you find the worms in clusters. Replace the left-over contents back in the bin. Be sure to add fresh bedding (6-8 inches) to the bin.
  3. Vertical Separation – By feeding the worms in the upper bin the worms will migrate to where the food is, leaving the compost in the bottom bin to harvest.

With all methods of harvesting, you will need to incorporate fresh bedding (6-8 inches) into the mix to ensure that the worms have enough to continue to “work” through. Once your mixture is harvested it can be used immediately or it can be stored for later use. It is best to incorporate it lightly with the preexisting soil in the vegetable garden or around trees and shrubs. Vermicompost can also be used as a top dressing for your lawn.

Sometimes worm bins may have issues that arise over time. It is important to note that your bin should not:

  • smell bad (could be that the bin is too wet, or not enough air is moving through, or too many food scraps have been added),
  • attract flies (could be too much food has been added, or food scrapes have not been buried enough),
  • have mold (could be that conditions are too acidic),
  • have dry bedding (could be too much air is moving through the bin)
  • have large numbers of worms dying/crawling out of the bin (could be too much food or too little food has been added, or the bin has been exposed to extreme temps, or the bin is too wet or too dry), or
  • have lots of liquid in the bottom. This is called leachate and should not form in the bottom of the bin (could be too much food has been added or that there is poor ventilation or overwatering). It is important to note that leachate is not compost tea and should not be added to your garden.

Vermicomposting is a way to get earthworms to work for you and convert your organic waste into a valuable soil amendment that you can use in your garden! Over time you will learn to understand feeding, worm care, and how to best harvest your compost. For more questions regarding Warren County Soil and Water Conservation District programs and/or technical assistance on water or soil questions, visit or call, 513-695-1337. 

Short Recap: 

Vermicomposting is a way to get earthworms to work for you and convert your organic waste into a valuable soil amendment that you can use in your garden!

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