JoAnne Skelly: Worm composting in the house or garage

Red wriggler worms are decomposing work horses. They eat paper and food scraps turning them into compost, a nutrient-rich material for plants.

I asked Cory at the Greenhouse Project to share a worm composting method. He suggests a three-bin method, starting with plastic bins approximately 1.5 feet by 2.5 feet. The boxes are shallow because worms are surface-dwellers and prefer to live in the top 6 inches of bedding material. The first bin on the bottom is empty. It catches the drippings that drain or fall from the upper bins, which can be used as compost tea.

The second bin is where the worms live initially and it is stacked on the first bin. It has 1/8-inch holes drilled in the bottom to allow the excess moisture to escape and air to get in. Bin two is filled with dampened shredded paper such as computer paper, paper towels or newspaper into which red wriggler worms are placed.

Bin three is added after the worms have made compost in bin two. Bin three also has holes in the bottom and shredded paper bedding. Once bin two is filled with compost, start adding kitchen scraps to the damp shredded paper in bin three and the worms will migrate from bin two into bin three. Cover the stacked bins with a loose-fitting lid that allows air in.

Order red wrigglers online or look for them on craigslist.com. They are smaller than earthworms and more efficient eaters.

Start with damp shredded paper until the worms get established. They will feed on the newspaper. Depending on the temperature (the process is slower in the cold), worms can establish in a week or so. Once you start seeing more worms in bin two, you can start adding in raw fruit, vegetable scraps and coffee grounds.

Stay away from meats, oils and dairy products, which take longer to break down and can attract pests. Cooked foods are often oily and can also attract pests or smell. Avoid citrus fruits, which are too acidic and can attract fruit flies. Stay away from onions and broccoli, which are smelly.

Layer the kitchen scraps in and among the paper strips. If your bins stink, they need more air so mix in more paper or dried leaves.

After a while, there will be less bedding and more compost in the worm bin. When it is filled with compost rather than bedding, remove the finished compost from the bin and use it on plants. Bin three allows the worms to separate from their castings, which, at high concentrations, create an unhealthy environment for them.

For details, go to http://compost.css.cornell.edu/worms/basics.html.

JoAnne Skelly is associate professor and Extension educator, Emerita at University of Nevada Cooperative Extension. She can be reached at skellyj@unce.unr.edu.