Vermicomposting 101

Well, my worms are doing fine so I figured I'd make the post I promised a long time ago in which I explain vermicomposting. Vermicompost, in a gist, is intentionally feeding your food scraps and junk mail to a bin full of worms, who then poop out "worm castings" which you put in your garden.

White person's hands holding a handful of worms and soil.

What kind of worms?
Red wriggler or red earthworms. My worms were obtained from a neighbor who works as a middle school science teacher and who used them in a class project.

What can you feed them?
Feed them: non-oily vegan food scraps, egg shells, non-glossy paper, tea bags, coffee grinds and filters, dead but not diseased plants, hair and nail clippings from humans and pets, dryer lint, and old natural fiber rags. Keep a ratio of about 70:30 brown (paper and dead stuff) to green (plants) materials.

Do NOT feed them things that aren't on the list. Also, they don't like yeasted products or spicy food, and you should go easy on the citrus, onions, and garlics.

Cartoon of a worm sitting on a toilet with a newspaper that says "poo of today."

What's so great about worm castings?
Worm castings are rich in water-soluble plant nutrients like calcium, magnesium, nitrates, phosphorus, and potassium. They also have over 50% more humus than is usually found in garden topsoil. And it has a neutral pH, which is important for plant growth. Plus it contains beneficial microbes and bacteria.

In case you're wondering what humus is: Humus is the molecules left of decomposed organic materials once they're done decomposing. It basically acts like a big sponge and can hold 90% of its weight in water. So a soil that is rich in humus is a soil that will hold moisture longer and release it slowly to your plants. It will hold nutrients in the same way. And it also helps make a loose soil structure that is easier for gardening.

What sort of home do they need?
I have a fancy pants worm bin from Plum's earlier attempts at vermicomposting. But the neighbor that gave me the worms had made his own worm bin by taking an old lidded plastic bin and drilling air holes in the lid. Whatever you use for a bin, it should be kept somewhere between 55-75 degrees F so you don't freeze or overheat your worms. You also need to make sure it stays moist, which you can do by misting them if the soil looks dry.

Picture of seedlings growing in tiny containers with percentages of worm poop in each container labeled. The container with 20% worm poop has the biggest seedlings and the one with 0% has the smallest.