Red worm bins are great for a small-space composting setup that will yield free, nutrient-rich compost for your garden.
Worms eat kitchen scraps and create worm castings, which are a valuable soil amendment and plant tonic. Castings are often called fertilizer, and though they are not very high in nitrogen, they are full of plant-supporting nutrients.
Vermicompost, or compost made mostly by worms, is seven times richer in plant nutrients compared with compost created mostly by fungi and bacteria. Recent studies suggest that small amounts mixed into soil suppress diseases, slugs and insects.
Sprinkle castings on potted plants and over garden beds. A little goes a long way. You can drop a handful into the bottom of a planting hole to get the 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% castings, to make an extra-rich growing medium.
Here is what to 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. Worm bins make 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 in the soil 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. Everything 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
Worms are hermaphrodites, so they aren't picky about mates. They breed at a rate that puts rabbits to shame. If you’re willing to be patient, you only need to hunt up about a cup of them to get started. If you buy them, you’ll buy a full pound — that’s usually the minimum amount on offer. Whichever way you go, it all works. More worms eat more scraps and make more castings. If you start with lots of worms, the bin will be productive faster. If you start with only a handful of worms, they’ll start breeding as soon as they settle into their new home, and you’ll be up to speed in a couple of months.
Gulley Greenhouse has red worm bin workshops every March! Check our classes page for more details.
It’s also fun to hunt for worms in your garden. The worms you want aren’t the big, fat night crawlers; they’re the smaller red or purplish worms that live close to the surface of the soil. You can find them in leaf litter or in cool compost. They are most populous in spring and fall and can be hard to find in summer and winter. Make a trap for them by burying something tasty in your garden beds or in an area rich with leaf litter. Worms adore squash. It draws them like a magnet. You could also use leftover oatmeal or wet bread. Bury these offerings an inch under the soil or leaf litter and come back in about three days. Scoop them up and take them to their new home.
Which Worm Is Which?
Red worms (Lubricous rubellas) are the worms you most often find in leaf litter and garden beds, but they also hang out in compost piles. Compost worms (Eugenia fetid) are about the same size and can be red too, but they also come in purple and tiger-striped varieties. These are true compost worms whose preferred habitats are compost and manure piles. Eugenia fetid is the type sold for worm bins, but Lubricous rubellas adapt to life in the bin very well.