Thursday, June 4, 2009

Composting with Worms

On Friday mornings we put our milk jugs, beer bottles, soda cans, and newspapers out for recycling. This act helps reduce the amount of new raw materials needed to create glass, aluminum, and paper, but it also cuts down the solid waste that we are sending to county landfills. One big source of solid waste that we may not be "recycling" -- but we could -- are our kitchen scraps. Vegetable and fruit scraps are easily recycled through composting.

Composting is the process of decomposing organic matter into humus, the dark, rich material that is essential for healthy soil. Many people are already familiar with compost bins or tumblers that facilitate the decomposition of yard wastes and kitchen scraps. In that method, bacteria and fungi do the decomposing. There is another method of composting, however, that is not as well known but is easy and effective, and that is worm composting.

Worm composting, or vermicomposting, does not rely on bacteria and fungi but rather on worms to consume kitchen scraps. As the worms eat the food scraps, they leave behind their excrement, known as castings, which are highly enriched with nutrients, minerals, and microorganisms. Worm castings are one of nature's most potent fertilizers. They feed both the soil and the plants that thrive in it, and worm castings are not dangerous to plants in any concentration or application.

We mentioned in an earlier post a great composting guide, The Rodale Book of Composting. This fantastic book has a chapter on composting with worms. The classic on the topic, however, is Mary Appelhof's Worms Eat My Garbage. The Baltimore County Library system has many copies, as do area bookstores. Mary Appelhof's website,, is a great resource as well.

My family took the plunge and began worm composting in April of this year. I ordered one pound of Red Wiggler worms, roughly 1000 worms, for $19.95 from Uncle Jim's Worm Farm in Spring Grove, Pennsylvania. The worms arrived safely a few days later in a bag of peat moss, and we began composting immediately.

Worm bins come in a variety of shapes and configurations and can be purchased online easily. However, we chose to make one from plastic bins purchased locally (and inexpensively). We bought three Sterilite brand 28 qt. bins, roughly 5.5 inches high, 16 inches wide, and 22 inches long, costing about $7 each.

Worms need air, darkness, moisture, a few inches of bedding, and food to thrive. To provide air we drilled holes into the sides and bottom of two of the bins, leaving the third bin undrilled. For the drilled bins, small holes of 1/4" ring the bin about midway up the side, while 1/2" holes are spread out around the sides and bottom.

Unfortunately, we didn't realize the true significance of worms' need for darkness until it was a little late. As can be seen in the photo below, the bins we purchased were transparent. We thought the basement would be dark enough for the worms. We were wrong. The worms did not thrive.

We realized that the worms were concentrated in the center of the bin, avoiding food on the edges. After applying a coat of black spray paint to one of the bins and transferring the bedding and worms to it, the worms have moved into every corner of the bin.

Tip: When making your own worm bin be sure to buy opaque containers.

To provide moisture, we shredded newspaper and submerged it in water briefly to achieve a moisture level like that of a wrung-out sponge. This bedding is then placed into the first bin, filling it completely.

Lastly, a small portion of food scraps is placed in one of the corners of the bin. The resources listed above can provide a list of foods worms can eat. Our worms did not like potatoes but loved asparagus, cantaloupe, and coffee grounds.

The worm bin sits inside the one undrilled bin which catches any liquid, bedding, or worms that might fall out of the worm bin. To allow air circulation, a few blocks of wood are placed in the bottom of the undrilled bin to elevate the worms.

We have been feeding our worms every week for eight weeks now. The bottom of the bin is filling with castings and baby worms are visible all over the bin. In the next month or so we will be ready to move the worms from bin 1 to bin 2. When we get to that point, we'll post on it.

If you have any questions about setting up a worm bin, please ask.

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