Using earthworms to break down organic matter is called vermicomposting or worm composting. The worms produce castings that are called vericompost, a natural soil conditioner and fertilizer that is rich in nutrients. What to feed worms, and how much, is largely a matter of knowing what they like and how much they can handle.
Top Feeding/Pocket Feeding
In top feeding, you spread food on the top layer in your bin and cover it with another layer of bedding. In pocket feeding, you bury the food in pockets in different places in the top layer and cover with other parts of the top layer.
After your worms have been at home for a week, start feeding them. Eisenia fetida, the most popular composting worm will chow down comfortably at anywhere between 55 and 70 degrees Fahrenheit.
Feed in small amounts a couple of times a week. You can feed them more often if you use a lesser amount of food. Give them only what they will eat or compost bin will start rotting and begin to smell bad.
Add something gritty to help your worms digest their food: sand, soil, sawdust or ground eggshells are all good. If you want to feed them more, chop up the waste into finer bits or add more worms. The greater the exposed area of chopped-up food, the easier it is for worms to eat. Adding blended food can make the bin too wet.
If you have more chopped scraps than your worms can handle, put in a plastic bag and freeze. You can thaw it out later and feed it to them then.
Foods Worms Love
Worms love corn cobs, pumpkin, and the rinds of watermelon and cantaloupe. They like fruits, vegetables, potato peels, lettuce, old bread, spaghetti, tea bags, coffee grounds, crushed eggshells and banana peels. They will tolerate garlic, onions and citrus fruits.
What Not to Feed Worms
Don't feed worms meat or dairy products. Worms will eat meat, but it takes longer for them to digest it; in the meantime the meat rots. Don't feed worm salty or oily foods or bones. Also don't feed them glass, aluminum foil or other inorganic waste or newspapers with colored ink. Don't feed them grass clippings. Too many grass clippings can build up heat and kill your worms. Use your grass clippings in your hot compost pile.
Worms eat tomatoes, but not the seeds. If you feed them tomatoes, you might have small tomato plants popping up in your compost.