Bobby Little
Adams County Master Gardener

Many gardeners who have compost bins in their gardens are only fair-weather composters, including me. With a compost bin 200 feet from my house, a special trip there with potato peels in the middle of icy cold January doesn't hold much appeal. An alternative is worm composting, which can take place in your basement using the same kitchen scraps you toss in your outdoor compost bin. The difference is using worms, specifically red wigglers, that will be perfectly happy consuming your vegetable or fruit scraps or other things that rot.

Why worm composting? The primary reason is to generate worm castings, the polite word for 'worm poop,' a magical potion you can spread in your garden. Worm castings provide various nutrients, primarily nitrogen and phosphorus. They also help improve your soil's water retention. I became a believer after my 2005 vegetable garden was the best I ever had… until the drought struck. Worm castings are available through many garden centers, but are somewhat costly. A small 5 lb. bag costs $20, so why not grow your own?

To get started, find a 10-gallon or larger opaque plastic, wooden, or metal container. Holes must be drilled in the sides and the bottom to allow air into the container. Light must be blocked from entering the container, hence the opaque materials. Cedar, redwood and pressure treated lumber should not be used because of excess acidity or chemicals that may harm the worms. The container should be raised off the ground an inch. Start with a bed of thoroughly wet newspaper, squeezing out all excess water. Only black ink newspapers should be used. Add a combination of damp potting soil, humus or other organic plant material. All materials should have the consistency of a well wrung sponge, a useful concept to remember since red wigglers like moisture, but not too much. To keep it simple, the portions can be 1/3 newspaper, 1/3 potting soil and 1/3 peat humus. Next add red wiggler worms. There are many sources available online. You can start small with a half pound or 400-500 worms per 10 gallon quart container. They will multiply rapidly and a 10 gallon container can easily support 6,000 worms. Place some food on the surface of the soil since the worms come there to feed. They will not survive Pennsylvania winters, so it's best to keep them in temperatures between 55 and 75 degrees. I keep an old damp T-shirt over top of the bedding material to help retain moisture, but after only a few months, the worms have eaten most it!

Worm food can consist of vegetable or fruit scraps, bread, tea bags, paper towels, leaves, pasta, or any other material that will break down with time. Avoid foods that attract rodents, such as dairy products, meat, and oils. Also avoid salty foods and acidic products. Egg shells are great for the calcium. A variety of different food types are ideal because of the nutrients they provide the worms.

You can harvest castings after the worms have been established for a few months. Simply move the food to one side of the bin and the worms will work their way to that area in a few days so you can scoop the castings from the other side. Mix the castings with water to create a 'tea' for potted plants or work it into the ground when planting seedlings. Use it when repotting plants, or anywhere you'd use fertilizer or need soil improvement. That's everywhere, folks. The material is very mild, so there's little worry about accidental burning or over-fertilizing. Remember that other earthworms are already in your garden making castings.

Perhaps once every one to two weeks, gently mix the soil to increase air circulation. It should smell earthy with no offensive odors. As you examine the soil, you will see tiny young worms that look like pieces of thread and worm egg sacks that look like an amber colored match heads. They will grow quickly with an appetite to match their size.

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