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Composting Indoors: Get Worms Working for You

By Contributor ; Updated September 21, 2017

by Susan Ward

You don't need to tote your food scraps out into your back yard or even have a back yard to enjoy the benefits of composting. Turn your food scraps into rich, dark soil right in your kitchen by setting up a red worm composter. Composting indoors is clean, odorless if you do it right, and a great way to cut down on the amount of trash you set out by the curb every week. All you need is a container, bedding material, redworms and food scraps to feed them.

The Container

You can buy "vermicomposting" (worm composting) kits, that provide everything you need, but building a bin is so easy, why go to the extra expense?

A plastic storage container purchased from a department store will work well or you can build a simple wooden box. Use the amount of food waste your family produces each week as a size guide, calculating one foot of surface area for each pound of food waste produced. The container needs to be 8 to 12 inches deep; a plastic utility container approximately 24 inches by 16 inches by 10 inches is convenient for storing under the sink or in a cupboard.

Whether you choose a plastic or a wooden container, you'll need to drill holes in the lid and tops of the sides for air circulation and holes in the bottom for drainage. You'll also need a tray that you can put under the bottom of the composter to collect any excess liquid (which makes great plant fertilizer)! Placing the bin on bricks or wooden blocks also improves the air circulation.


You may want to line the bin with nylon net to keep the smaller worms inside. Fill the composter with about a foot of damp bedding (as moist as a wrung out sponge). The bedding is the worm's living space. If it's too wet, they'll drown; if it's too dry, they'll shrivel up. Maintaining the right moisture level isn't difficult once you're feeding the worms regularly.

Shredded newspaper makes excellent bedding material, as long as you use newspaper with nontoxic (vegetable-based) ink. (The worms eat their bedding eventually.) Other good bedding materials include sawdust, shredded cardboard, shredded leaves, dried grass clippings, loam, or black topsoil. Varying the bedding material will give the worms more nutrients and produce richer compost. You'll want to keep a small pail of soil handy so you can add a handful or two each time you feed the worms; this 'grit' helps the worms' digestion.

The Worms

The best worms to use for indoor composting are red worms (also known as red wigglers, brandling or manure worms). Unlike the earthworms out in your yard, red worms thrive on organic material. In fact, a single red worm can eat up to its own body weight in food scraps every day!

If you live in a rural area, you can get red worms from farmers who have aged manure piles (the red worm's favorite habitat). Red wigglers are often sold as fishing bait. Your local garden centre or community garden should be able to tell you where you can get the worms you need.

To estimate how many red worms you need for an indoors composter, plan on using one-half-pound of red wigglers for each cubic foot of worm bin; (one-half-pound of red worms is about 500 worms, depending on their size).

Red worms are happiest at room temperature, although they'll survive at temperatures ranging from 40° F to 90° F. Red worms need to be protected from hot sun, heavy rain and cold. You can keep your worm bin in the basement, shed, garage, or on your balcony if it stays warm enough; in a kitchen or closet is ideal.

Feeding the Worms

Use a small pail (such as an ice cream pail), to collect food for the worms; they like tea bags, coffee grounds and filters, vegetable and fruit scraps, bread, rice, and pasta. Don't collect meat scraps, bones, dairy products, garlic or potato peelings, as these will attract insects or cause odors.

When the pail is full, chop the food waste up a bit and feed the worms by pulling aside the bedding, burying the food waste deeply, and covering it with bedding again. If you start at one end of the composter and add food waste systematically to a new section each time, until you work back to the original site again, you'll be able to get a good idea of how your worms are doing; if there's still a lot of uneaten food in the first location, the worms are behind. Just wait a few days until you add more scraps.

It's a good idea to add some crushed eggshell each worm-feeding, to keep the bedding from becoming too acidic. Sprinkle the tiny pieces over the top of the bedding. Other than giving them some crushed eggshell, your pet red worms will be a cinch to look after; they don't need to be fed on any regular schedule, they're quiet, and you don't need to look for a wormsitter if you go off on vaction.

Harvesting the Compost

In 4 to 6 months, your worms will have turned their bedding and food into rich, black soil and it will be time to decide how you're going to harvest it. You can either use the "dump" or the "migration" method.

The "dump" method is just what you suspect it is. Dump the contents of the bin onto some newspapers or a plastic sheet and separate it into cone-shaped piles. Then, because worms are light-sensitive, shine a light on the piles for about ten minutes. The worms will start to move towards the center of the piles.

Scrape the finished compost of the sides of the piles. (Watch out for the tiny, lemon-shaped worm cocoons that contain the baby worms as you're scraping.) Do this several times, and you'll end up with a bunch of worms at the bottom of the piles. Put fresh bedding in the bin and reintroduce the worms. Children often love to help when you use this technique.

The "migration" method is just as easy. All you need to do is move the compost to one side of the bin, and put fresh bedding on the other side. If you add food only on the side with the fresh bedding for a few weeks, all the worms will move to that side, and you can then remove the compost. Add some more fresh bedding, and continue feeding as usual until it's time to get ready to harvest again and repeat the process. Worms don't talk much, but I suspect they find this method less traumatic.

The Finished Product

Red worms may not be good-looking, but they sure work hard. As long as you keep replacing their bedding and feeding them, they'll keep producing rich dark compost. Use the finished product as is as top-dressing around plants in containers or beds, dig it in anywhere you want to improve the soil, or put a mesh bag of it in a pail of water to create compost tea to perk up your plants. Nothing improves soil like compost, and nothing could be easier than worm-composting indoors.

Copyright Susan Ward; All Rights Reserved.


Vermicomposting. (2000). In Your guide to composting.

Waste reduction at home: Worm composting (2000). In Composting at home.

Worm composting (2000). In Backyard magic: The composting handbook.


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