How to Make a Worm Bin

Make a worm bin for a great small-space composting setup that will yield free, nutrient-rich compost for your garden.

| July 25, 2011

The following is an excerpt from Making It: Radical Home Ec for a Post-Consumer World by Kelly Coyne and Erik Knutzen (Rodale, 2010). In this ultimate guidebook for living a homemade life, Kelly Coyne and Erik Knutzen take back home ec and restore it to its original, noble form, in which the household is a self-sustaining agent of production at the center of your life. With projects ranging from the simple to the ambitious, you’ll build all the skills you need to do everything from making your own laundry soap to becoming a backyard beekeeper. This excerpt is from Chapter 61, “Worm Farming.” 

Worms eat kitchen scraps and create worm castings, which are a valuable soil amendment and plant tonic. Though castings are often called fertilizer, they’re actually not very high in nitrogen, but they are full of plant-supporting nutrients.

Sprinkle castings on potted plants and over garden beds. A little goes a long way. A handful can go into the bottom of a planting hole to get a plant off to a good start. Unlike nitrogen-rich fertilizers, worm castings won’t burn the plant’s roots. They can also be mixed with potting soil, in concentrations of up to 20 percent castings, to make an extra-rich growing medium.

Here’s what you should know before you start: A worm bin is a supplement to a compost pile, not a replacement for one. Worms don’t consume indiscriminately the way a compost pile does, and they can only eat so much at a time. But, as we said above, castings are a fantastic resource, so it’s well worth keeping both a worm bin and a compost bin. That said, a worm bin makes a fine green-waste disposal system for an apartment dweller. If you don’t have yard trimmings to worry about, worms can handle a good deal of your day-to-day food waste — such as coffee grounds, wilted lettuce, stale bread and so on — and give you castings in return that you can apply to container plants.

Worm bins are best kept indoors. Worms thrive in temperatures between 50 and 75 degrees Fahrenheit, and those conditions are usually found in the cool parts of a house instead of outdoors. During hot summers, worms dig down deep to keep cool. They can’t do that in a worm bin, which will heat up to ambient summer temperatures. In winter, freezing cold will kill them, too. Of course, it all depends on your climate and situation. If you have cold winters and mild summers, the worms could spend the summer outdoors and the winter indoors. Or in the opposite situation, they could come in for hot summers and stay out for mild winters. You can also take steps to keep the bin’s temperatures reasonable, such as insulating it. Just remember that when temperatures are extreme, worms are unhappy.

Sourcing Your Worms

While you can buy worms from online suppliers, it’s more fun to get them from a friend who keeps worms or to hunt them in your own garden. Worms from a friend are truly local and already well-adapted to life in a worm bin. In addition, they’ve not undergone travel stress. Mail-order worms are understandably freaked out on arrival (as freaked out as worms can be) and will often try to escape from the bin their first few nights before they’ve calmed down.

Alicia Previn
5/21/2012 9:09:00 PM

Get your children involved by introducing them to The Earthworm Book, a children's picture book that tells them how important they are in this big world, but how a tiny creature can turn garbage into gold that helps the soil become living and able to grow and protect your gardens. The book comes with a full-length CD audio book and The Earthworm Song (kids and adults love it) and explains how to build a simple worm box at home. Visit for more information

7/28/2011 1:58:36 PM

Gayle,I run a hot compost, where the maggots will die off no problem. In a worm compost I don't think they will displace the worm population, but they will mature to nasty buzzing flies. You may want to consider burying that batch in the ground to rot more hygienically. I am considering augmenting my compost row with a dedicated worm pile. //P

7/27/2011 1:03:11 PM

I took a little long emptying my kitchen waste bucket, and got a TON of maggots, which turned into really big whitish worm crawler things in the worm bin, I'm guessing from flies. Wondering if these crawler worms overcompete with my redworms and if I should toss out this batch?

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