These are not the usual big burrowing earthworms that live in garden soil. Called red worms, tiger worms, brandlings, angle worms, manure worms, or red wrigglers, they occupy a different ecological niche, living near the surface where there are high concentrations of organic matter, such as on pastures or in leaf mould, or under compost piles.

Two breeds are used in vermicomposting: Eisenia foetida or Lumbricus rubellas. Many garden centers now supply them, and in most countries they can be bought by mail order from worm farms. Some sellers advertise special high-performance breeds or specially developed hybrids, but don't believe them -- they'll be one of these two breeds. There's no such thing as a hybrid worm.

You'll need 1,000 worms (1 lb) to start a worm box, maybe twice that if you want to process your garden wastes too -- they breed very fast in the right conditions, but starting with more will give the system a good start.

Worm populations double each month. In ideal conditions they can reproduce much faster than that: 1 lb of worms can increase to 1,000 lbs (one million worms) in a year, but in working conditions 1 lb will produce a surplus of 35 lbs in a year, because hatchlings and capsules (cocoons or eggs) are usually lost when the vermicompost is harvested.

Mature redworms make two or three capsules a week, each producing two or three hatchlings after about three weeks. The hatchlings are tiny white threads about half an inch long, but they grow fast, reaching sexual maturity in four to six weeks and making their own capsules. Three months later they're grandparents!

This rapid breeding rate means the worm population easily adjusts to conditions in the worm box according to the feed supply and the proportion of worm casts to feed and bedding -- their casts are slightly toxic to them, and as the box gets "full" they'll either leave, if there's anywhere for them to go, or they'll die off.

This is an important consideration -- if you only want the vermicompost for the garden it doesn't much matter if the worms die off, as long as you've kept some aside to set a new box going. It also makes it easier to harvest the castings, and you'll have a higher proportion of pure castings.

But if you want to produce excess worms as well, to extend your worm system, for sale as fishing bait, or to feed to poultry or fish (they really thrive on wormfeed), you'll need to separate them from the vermicompost before the proportion of castings gets too high.

Fill the box with moist bedding for the worms to burrow in and to bury the food scraps in. You need about 6 lb (dry weight) for a 2ft x 2ft x 8" box. Worms will eat the bedding as well as the food scraps, so you'll need to top it up in a few months.

• Cardboard cartons (corrugated): cut them up into strips an inch wide and a few inches long. Don't use the shredded cardboard sold for insulation because it's treated with toxic chemicals.
• Newspaper: tear it into 1" strips -- it's easy to tear with the grain. Black ink is non-toxic, avoid glossy paper.
• Shredded computer paper.
• Autumn leaves: spread them thickly in the driveway and drive over them with the car a few times to break them up, or shred them with a lawnmower. Or moisten them, sprinkle some lime, ground limestone or wood ash over them and bundle them up in a garbage bag, tie the top closed, and in a few months they'll have broken down enough to be excellent worm bedding. Or just use them as is, though it'll take a bit longer for the worms to break them down.
• Aged manure, or composted manure: cow, horse, rabbit.
• Sphagnum peat moss: use Canadian peat moss, soak it in water for 24 hours, squeeze it out and sprinkle some lime on it.
• Coco peat moss or coir (coconut fibre): comes in compressed bricks, soak in water and they swell up -- no need to add lime.
• Chopped-up straw or other dead plant material, spoiled hay, yard clippings, dried grass clippings: any plant material "aged" beyond the green stage.
• Sawdust, wood shavings: from non-aromatic wood, avoid treated wood, about a quarter to a third of the bedding mixture.

Add a couple of handsful of soil or sand -- it helps the worms grind up the food in their gizzards. Sprinkle a bit of lime, ground limestone or wood ash over the bedding (not too much!). Ground limestone is best.

Worm bedding and feed can be wetter than compost material: 75%, compared with 65% maximum for compost. Dry bedding usually needs a bit less than three times its weight in water (a pint of water weighs a pound, a liter weighs a kilogram).

Once it's all suitably shredded, mixed and moist, put it in the box and add the worms (about 1lb -- 1,000 worms). Leave it for two or three days to let the worms settle in before adding wastes.

No metal, foil, or plastic. Use vegetable and fruit scraps, coffee grounds (including paper filters), tea bags (remove the staple), eggshells (best dried and crushed first, then sprinkled over the surface), stale bread, houseplant trimmings. Chop up big chunks. Some people advise against citrus, and also onion and garlic, others use them: try small quantities first. Not too much vegetable oil, be cautious at first with dairy products, meat and fish -- small amounts chopped fine, well-dispersed and well-covered with bedding should be okay. Broken chicken bones are okay, bigger bones won't break down but shouldn't cause problems either -- they'll be picked clean.

It's best to collect food scraps in a small bucket with a lid and add them to the worm box every couple of days (or more often in hot weather -- don't let it go rotten). Bury them in the bedding in a corner of the box. Next time, bury the new scraps near the first scraps. You can have about nine burial sites in a 2x2ft box: by the time you've used the ninth one, you can go back to the first site again, the worms will have cleared it.

You'll be surprised how much feed you can put in that box -- the worms and micro-organisms reduce it more than you'd think possible.

The box will need emptying every 3-6 months.

Best tool for burying feed: a three-pronged hand-cultivator (hand-fork).