Worming Your Way To Rich, Black Compost
Worm composting (or vermicomposting) is a natural and efficient way to recycle your
organic kitchen scraps. And it sure beats plowing through knee-high snowdrifts to the
compost pile in the middle of winter! Worm bins really require very little in the way
of maintenance and care. You can keep them anywhere the temperature will not go down
to freezing such as a basement, insulated garage or under the kitchen sink. The best
temperature range is 55-77 Fahrenheit.
This is a great project to do with kids; it's easy to make compost using worms as long
as you have the right container, bedding material and the right worms. And the finished
product, consisting mostly of worm castings, can be used with perlite to make a houseplant
potting mix, added to planting holes when transplanting seedlings, or simply incorporated
into flower or vegetable beds.
You can either make your worm bin yourself or order it from a number of different sources
(listed later). Common materials for a do-it-yourself project are opaque plastic storage
boxes and wooden boxes built from exterior-grade plywood. A basic design would be 1 foot
high, 2 feet deep and 3 feet wide with aeration holes in the bottom. Depending on the size of
your container, you'll need to drill 8 to 12 holes (1/4-1/2 inch in size) in the bottom. A
simple cover can be made from a sheet of black plastic. A cover will help conserve moisture
and provide darkness for the worms. A box this size will accommodate about 6 pounds of kitchen
scraps a week (the average amount from a family of 4-6). You will need to keep the bin
elevated at least an inch off the ground for air circulation. Place a tray underneath to capture
excess liquid which can be used as liquid plant fertilizer.
The bottom of your bin will need to be lined with a 2 to 3 inch layer of bedding material.
Cellulose-based materials like shredded newspaper, corrugated cardboard or coarse sawdust
are best. Tear newspaper or corrugated cardboard into 1 to 2 inch-wide strips. Before putting
bedding material into the bin, dampen it with lukewarm water until it has the same moisture
content as a wrung-out sponge. Adding a little garden soil or leaf mold to the bedding will
provide microorganisms for the composting process and grit for the worms' gizzards. Check your
bedding at least once a week to make sure it stays damp. Add water if necessary by misting with
a spray bottle.
After spreading the bedding over the bottom of the bin, you're ready to add worms! What worms
do you buy? Of the 17 species available in North America, you want redworms or red wrigglers.
You can buy them at a bait shop or through mail order. You want redworms because they can process
large amounts of kitchen scraps, don't mind confined spaces, reproduce well in culture and
tolerate a wide range of temperatures. For the bin described above, you'll need about 2 pounds
(about $25-$35). You'll get between 600 and 1,200 worms per pound. They will be red and from
2 to 4 inches long. Put your worms on top of the bedding and watch them quickly burrow to escape
light.
Now comes the fun part, feeding your worms. Put leftover kitchen scraps into the bin: vegetables,
fruit rinds and peelings are great. Bread, coffee grounds, cereal, crushed eggshells, pasta or rice
and houseplant clippings are also okay. Food should be cut into small pieces and buried in the
bedding every few days. By covering food waste with a few inches of bedding, you avoid odors and
pests (like fruit flies). Rotating the burial places in the bin will provide your worms with a
balanced diet of kitchen scraps and bedding. As with outdoor compost, you want to stay away from
meat, bones, oils and dairy products.
After 6 or 8 weeks of feeding the worms, most of the bedding should be gone and a dark, crumbly
soil-looking material should be in its place. Now it's time to harvest. Do this by pushing the
nearly finished compost to one side of the bin. Put fresh moistened bedding with some fresh garbage
in the vacant side. Over the next few weeks the worms will migrate to the new bedding, and you can
harvest. Take the finished compost out, and put fresh bedding in, starting the cycle all over again.
On occasion, unpleasant odors may waft from your bin when it is overloaded with food waste. If this
occurs, gently stir up the entire contents to allow more air in. Stop adding food waste until the
worms and micro-organisms have broken down what is in the bin. If that doesn't solve the problem,
check the drainage holes to make sure they are not blocked. Drill more holes if you need to. If
the moisture level seems right, the bedding may be too acidic due to a lot of citrus peels and
other acidic foods. Adjust by adding a little lime and cutting down on acidic wastes.
Discourage fruit flies by always burying food scraps and not overloading the bin. If flies persist,
move the bin to a location where the flies will not be bothersome.
If you're interested in more information on worm composting read Mary Apelhof's
book, Worms Eat My Garbage (1997) or check out the Worm
Digest.
The following are sources for composting supplies and worms:
- Flowerfield Enterprises-10332 Shaver Road, Kalamazoo, MI 49002.
(269)327-0108
- Gardeners Supply Co.-128 Intervale Rd., Burlington, VT 05401
(800)833-1412, minimum 2lb order-available mid-March to November
- Vermico, Peter Bogdanov - 4425 Galice Road, Merlin, OR 97532
(541)476-9626
- Willingham Worm Farm-Route 1, Box 241, Butler, GA 31006.
(478)862-5545, e-mail: wworm@gnat.net
- Worm World - 26 Ihnat Lane, Avella, PA 15312-2106. (724)356-2397
