Garden innovations - worm bins

Worm composting, or vermiculture, requires very little work, produces no offensive odours, and helps plants thrive. It's not a new technology, but the new bins and worm cultures have made it a trouble free experience.

Your bin needs to be around ten to sixteen inches deep, since compost worms are surface feeders. You need to be sure your bin has a lid to keep out flies and rodents, and holes in the bottom a quarter inch or smaller, for ventilation and drainage. The rule of thumb for bin size is two square feet of surface area per person, or one square foot of surface area per pound of food waste per week. Because worms like moderate temperatures, place it in a shady location where it will not freeze or overheat.

Black and white newspaper is the most readily available and easy-to-use bedding material. Tear it into strips about one inch wide and moisten so it is as damp as a wrung-out sponge and a handful or two of soil, ground limestone, or well-crushed eggshells every few months are good for providing grit and calcium. Fill your bin with moistened bedding, toss in a few handfuls of soil, and you are ready to add the worms and food. Over time, the bedding and food are eaten by the worms and turned into dark worm compost.

The best kind of worms for composting are often found in old compost piles. These worms have a big appetite, reproduce quickly, and thrive in confinement - and they can eat more than their own weight in food every day! Many organic garden centres supply worms by post now.

Worms will devour stale bread, apple cores, orange peels, lettuce trimmings, and all kinds of non-greasy leftovers. Do compost: vegetable scraps, fruit peelings, bread and grains, tea bags, coffee grounds including filters, and well-crushed eggshells. Do not compost: meat, bones, fats, dairy products, rubber bands, twigs and branches, dog and cat waste and greasy foods. Begin feeding your worms only a little at a time. As they multiply, you can add larger quantities of food. Bury the waste into the bedding regularly, rotating around the bin as you go. When you return to the first spot, most of the food you buried there should have been eaten. If not, don't worry. Just feed the worms less for a while.

After you have been feeding your worms for three to six months, you may notice the bedding has been eaten, and you can begin harvesting the brown, crumbly worm compost. Harvesting the compost and adding fresh bedding at least twice a year is necessary to keep your worms healthy.

Worm compost is more concentrated than other composts, so use it sparingly for best results.

Garden innovation worm bin photograph by sporkist, used under a creative commons attribution licence