Compost worms are beneficial nematodes that break down organic waste and turn it into nutrient-rich worm castings that can be used to fertilize your plants. Red wrigglers, the type of worms that tend to live in compost heaps or worm bins, feed near the surface of the soil. Other types of earthworms in your garden live deeper down where they break up buried organic matter like old root clumps. Worms in your garden also work for you by aerating and turning the soil.
Start a worm bin to grow your own red wriggler composting worms. Worm bins are usually kept indoors in a warm place, and you feed the worms with kitchen scraps. After feeding the worms for several months, there will be enough worm castings to harvest and use in your garden. Remove about half of the material from the worm bin (including the worms) and spread it in the garden. The castings will fertilize the plants and the worms will continue working the soil.
Check your compost pile for worms. If the compost is healthy, red wrigglers usually just appear there on their own. If you want to give your compost pile a boost of worms, add a few handfuls of worms from the worm bin or buy some from a garden store. Make several holes in the compost heap about 6 inches deep and bury the worms in them.
Increase the worm population in your garden by burying kitchen waste in the soil to feed them. The worms will create compost directly in the soil when they eat the food scraps. Use only vegetable and grain scraps and avoid meat and dairy products (except for eggshells). Find a bare spot in the garden and dig a hole about 1 foot deep. Fill it with about 4 inches of scraps and work them into the soil with a fork. Cover it well so animals don't dig it up.