How to Compost with Worms

By Cathy Cromell and The National Gardening Association from Composting For Dummies

3 of 4 in Series: The Essentials of Worm Composting

Vermicomposting is a composting method that employs certain worm species to consume and convert organic matter into a useful soil amendment and organic fertilizer. Provide moist bedding at all times for your worms to romp around in while they process your organic matter. Over time, worms consume their bedding along with your food scraps, but that's okay. By then, you'll be ready to harvest castings and provide fresh bedding.

Making bedding for your worms requires only two materials: two handfuls of native soil and newspaper or computer paper. You may also use leaves and shredded cardboard for bedding, either in place of paper or in addition to it.

Follow these steps to make your worms the sort of bedding they'll never want to leave:

Wash bins thoroughly before adding bedding and worms.
Tear paper into 1-inch (2.5-centimeter) strips.

Fill one side of your sink with water. Soak the paper in it. Lift it out and let excess water drain in the other side of the sink. Don't squeeze the paper because then it will dry into hard chunks.
Lightly place the paper in the bin.

Composting worms work in 8 to 12 inches (20 to 30 centimeters) of bedding depth. Fill the bin at least 12 inches (30 centimeters) deep because the bedding will settle a bit. Fluff up the bedding so that it's loose, with air pockets, rather than compacted.
Sprinkle two handfuls of your native soil into the bedding.

This provides grit for the worms' digestive process and adds microorganisms to aid with decomposition.
Bury one handful of food scraps in the bedding.

Don't overwhelm wigglers with too much food in the first week while they're getting acclimated. When these scraps are gone, add more, gradually working up to greater quantities.

Place your red wigglers on top of the moist bedding and they'll begin disappearing into it. If they seem slow to go, shine a bright light above the bin. They should dive for the dark depths.

Vermicomposting worms in your indoor bin eat the same organic goodies that you add to an outdoor compost pile, including spent garden plants, landscape trimmings, scrap paper, and kitchen scraps.

Plan on feeding your worms about half their weight in food scraps per day. When starting a new bin, offer just a handful of food until they get acclimated and start digging into your provisions. As a general guideline, feed your worms when the majority of the previous food has disappeared.

The more variety in ingredients, the better the vermicompost. Try not to overload your worm bin with fruit and vegetable skins, which may attract vinegar flies. Also, avoid lots of salty food waste, which will dry out the poor little worms. Worms are known to have food preferences (really), so experiment to see what your red wigglers prefer. Here's a hint: sweet mushy stuff like melon, pumpkin, and squash is often popular. Other good additions include

Raw or cooked vegetables
Coffee grounds and filters
Tea and paper tea bags
Stale bread and grain products
Ground-up eggshells
Fruit rinds and cores

Just as there are items that shouldn't be added to a regular compost pile, the following items aren't appropriate worm food:

Meat, fish, or dairy: These foodstuffs may turn rancid and smelly as they decompose, as well as attract undesirables such as houseflies or vinegar flies (also called fruit flies).
Greases and oils: Worms breathe through their skin. Oils and grease coat their skin and prevent them from breathing.
Pet or human waste: It may contain pathogens that are transmitted to humans.

Chopping scraps into 2- to 4-inch (5- to 10-centimeter) bits speeds the decomposition process in your vermicomposting bin, just as it does in your outdoor compost pile. However, it isn't always essential if you aren't in a hurry and your bin has been functioning well.