Making a Worm Bin

Most kids love to dig in the dirt, where they naturally uncover earthworms. These squirmy creatures pique kids' curiosity, and they can help keep many a child occupied while adults busy themselves with garden chores. And playing with worms is also a great way to teach kids appreciation for nature and her cycles, especially decomposition. Worms are nature's mini composters, improving the soil by creating channels for air and water, and by breaking down organic matter (including your vegetable scraps) and turning it into valuable fertilizer.

To start your own worm bin, you'll need an aerated container, bedding (such as shredded newspaper), a moist and temperate environment, a small amount of soil, and, of course, some worms.

Choosing a Home

The container can be as simple or as elaborate as you wish. You can purchase a fully equipped bin or convert a plastic dishpan or 5-gallon bucket to a worm home. Worms need only about 8 to 12 inches of depth to move around in.

To make your own bin, drill 8 to 15 drainage holes in the bottom of the container, depending on its size. Many worm farmers also drill holes in the side near the top edge to further enable air flow. (Some believe that holes 1/4-inch in diameter or less will deter fruit flies from entering.) You'll also need a lid -- made of wood, rubber, hard plastic, or a black plastic sheet -- to maintain darkness and moisture.

Raise the bin on bricks or blocks and place a tray underneath to gather excess liquid. Your bin size will affect how much food the worms can process per week. Allow one square-foot of surface area per pound of scraps per week.

HINT: If you use a clear plastic container, cover it with a dark cloth because worms don't like light. However, this is a fun way for kids to observe the worms. As you take off the cloth, you will usually see many worms against the side of the container. They will dart into the depths of the soil when the cover is removed.

Adding Creature Comforts

Fill your worm bin three-quarters full with damp bedding material, such as shredded newspaper (1-inch strips), dead leaves, or coconut fiber (coir). This is where you'll bury food waste. Adding a handful or two of good garden soil or mulch from the soil surface will provide the grit that worms need to digest food, as well as microbes that help break down organic matter. Bedding materials should be moist, but not wet: about like a wrung-out sponge. If using newspaper, dunk the strips in water and let them drain for just a few minutes before filling the container about two-thirds full. When necessary use a mister to keep the bedding moist or sprinkle small amounts of water in the bin.

Inviting the Guests

Redworms (Eisenia foetida), commonly known as red wigglers or manure worms, are the species most likely to survive in a worm bin. They need lots of organic matter and warmer temperatures than night crawlers or other garden-dwelling earthworms. One pound of worms (approximately 1000) will process 3 to 4 pounds of food scraps per week. You can obtain redworms through mail-order sources (such as the Gardening with Kids Store).

What's for Dinner?

Worms can "eat" approximately their own weight in food scraps every day. Keep it vegetarian, providing vegetable and fruit scraps, pulverized egg shells (for calcium), spoiled food, coffee grounds, and tea bags. Avoid meats, dairy products, and oily foods, which can create foul odors and attract flies and rodents.

Indoors or Out?

Locate worm bins inside or outside. In either case, temperatures should remain between 40 and 80 degrees F. If bins are outdoors, shelter from hot sun and heavy rain.

Tending the Bin

Have your young worm caretakers feed the worms slowly at first, gauging whether the food balance and moisture content seem adequate or need to be adjusted. A popular strategy is to divide your bin into 5 to 7 sections, then bury the food in a different section of the bedding each week. The worms will follow their nourishment around the bin.

Removing the Castings

After two to three months, when most of the food and bedding have been transformed into dark, rich compost, it's time to remove the worm castings (finished compost) because excess castings are poisonous to the worms. One method is to move the castings to one side of the bin, then place fresh bedding and food waste in the other side and let the worms migrate naturally, over time, to the fresh food and bedding. You can also dump the entire bin contents onto a plastic sheet and shine a bright light on the pile. The worms will migrate to the bottom to get away from the light, and (with gloved hands) your kids can then scoop the castings into a bucket. Then prepare new bedding and return the worms to the bin, where they'll start all over on a new batch of compost.

Courtesy the National Gardening Association's Kids Gardening Web site.