EXTENSION CORNER: Vermicomposting 101

Karen Welch, CCE-Yates County Master Gardener Volunteer
Vermicomposting (worm composting) is a simple and easy way to reduce your kitchen waste and some of your scrap paper and cardboard into valuable, nutrient-rich compost; a mixture of worm castings, decomposing organic matter, and microorganisms. Worms in a small bin can produce up to four pounds of castings in one month just from kitchen waste.

Worm composting, also known as vermicomposting, is a simple and easy way to reduce your kitchen waste and some of your scrap paper and cardboard into valuable, nutrient-rich compost. Here in the Northeast, it is a great way to compost these items in the colder months. It is also a great way for children to learn about composting and get involved in the process. What child isn’t interested in worms!

The worms will eat the food you provide and as it passes through the worm’s body it exits as nutrients that plants love. The worm compost is a mixture of worm castings (their poop), decomposing organic matter, and microorganisms. Worms in a small bin can produce up to four pounds of castings in one month just from kitchen waste. The paper and/or cardboard you provide are their “bedding.” Worms need a dark environment, moisture, and of course food! They do best in a temperature between 50 to 80 degrees. They like to be warm, but not too warm. You can purchase a worm bin or make your own using the directions below.

Supplies to get you started

  • You need two plastic bins. The shorter, bottom one does not need a top, and only needs to be deep enough to collect any of the “worm tea” that leaches out of your worm bin. The taller bin that fits on this should be about 2 feet by 2 feet by 8-12 inches. It will need a top.
  • About 1 pound of red wiggler worms (AKA eisenia foetida). Can be ordered online.
  • Light-weight non-metal screening to cover air holes
  • Water-proof glue to glue screen onto bins
  • Shredded black and white newspaper, peat moss or decaying leaves or a combination of these
  • Water
  • 1 pound of dirt

Preparing the bins

Drill a 1-inch hole about 2 inches from the top of the taller bin on opposite sides. Then drill about six holes that are 1/8 inch wide on the bottom of this bin. Cover all holes with the screening material. Place the taller bin inside the shorter one. Let the glue dry well before proceeding further. The holes at the top of the bin allow air for the worms to breathe and the holes near the bottom allow excess liquid to drain out of the box so the worms do not drown. This liquid is worm pee and is full of nutrients for plants.

Preparing the paper, soil, water and adding the worms

Add enough shredded paper to the taller bin to be about 3 inches deep and have some extra on hand to add a little more once a week. Avoid heavy, shiny, or colored paper. Add soil and just enough water to dampen all. The mixture should be moist, but not so moist that it forms puddles. Add the worms and let them adjust for a day before feeding. If you leave the lid off for a few hours, they will go to the bottom to avoid the light.

Feeding the worms

Worms will break down food faster if it is in small pieces. Add the food to one area of the bin each time and not all over. Cover the food scraps with the dirt and moist paper. If you notice the worms aren’t eating a certain food, remove it. It may be that they don’t like it, or it is too big, and needs cut up more. Add fruit and vegetable scraps but avoid citrus fruits, garlic, onions, and broccoli. Citrus fruits make the compost too acidic and strong -smelling vegetables can make the compost smell bad. You can also add eggshells (crunch them up so they are small), tea leaves and tea bags, coffee grinds and filters, feathers, and human or cat or dog hair. Do not put meat, fats, grease, bones, oils, plastics, milk, or dairy products, cat or dog feces, or any diseased plants into the bin.

Keep the bin as moist as a damp sponge. Always keep some shredded paper or sawdust on hand to cover over the top of the pile to discourage smells and bugs. Move the material around in the bin once a week to help aerate it.

Maintaining the bin

Once every 1-2 months scoop the liquid out of the lower container. This liquid, which is really worm pee, can be used as fertilizer outside near plants or watered down to use on indoor plants.

Your worm bin is full when the compost reaches the bottom of your top holes you drilled. When this occurs:

  • Feed your worms on one side only for a few weeks to draw them over to one side
  • Harvest the compost on the side opposite to where you are feeding the worms.

Other tips

- Keep a ratio of 70% brown matter (paper, sawdust, dried and dead plants) to 30% green matter (food scraps or young green plants).

- You can reduce the chances of fruit flies by freezing scraps for 24 hours before adding them and covering over food scraps with your brown matter.

- Make sure the worms have air! Once a week or so, move the compost around to aerate it.

This article was previously published in the Winter 2022 issue of Gardening Matters. Gardening Matters is a newsletter published four times a year in spring, summer, fall, and winter, and is put together by the Yates County Master Gardener Program. Complimentary copies of the Summer 2021 issue of Gardening Matters are available at the CCE-Yates County Office. For more information (or to view previous issues), visit our website athttp://yates.cce.cornell.edu/gardening/gardening-matters-newsletter, or call 315-536-5123.

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