Wednesday, April 16, 2008

Composting with Worms

Worms. They are all around you -- some in places you may never have imagined! Of course, during one of the wettest summers in 50 years, many of us are seeing worms almost daily on sidewalks and patios as they crawl out of their terrestrial burrows to avoid drowning.

But they are also showing up in some unexpected locations such as school classrooms, government offices, libraries (though not as "book worms"), and in tens of thousands of homes across the country. More and more people are learning to appreciate worms thanks to their remarkable ability to recycle (i.e., gobble up) apple cores, banana peels, and coffee grounds, and transform these and other organic materials into sweet-smelling humus or compost -- indoors!

Composting enthusiasts are used to seeing worms in their piles, and gardeners have long cherished coming across these beneficial wigglers as they work their garden plots. Small wonder, since worms are the world's first gardeners! They tunnel through the soil creating burrows which improve drainage and aeration, and eat decaying leaves and grass clippings, leaving behind lots of nutrient-rich castings, as they have for millions of years. Their value in helping to create healthy soil has been easily recognized since antiquity, with Aristotle calling them "the intestines of the world." More recently, Darwin spent a considerable portion of his scientific career studying these remarkable and essential organisms.

Today, all sorts of people are interested in harnessing the gentle power of the worm, some to understand more about the natural world, others to create compost for houseplants and gardens through vermicomposting (worm composting), and others for profit -- such as the many commercial worm farms nationwide. Fisherman are -- well -- another story.

It is important to realize that there are many different species of worm, each suited to a different habitat. Regular garden worms or nightcrawlers are great for the soil, but they would quickly perish in the indoor worm boxes used for vermicomposting. Similarly, the special redworms used for indoor composting would do poorly in an outdoor compost pile. Don't bother adding worms to an outdoor bin: they will come on their own. And do not spend money on worms or worm cocoons to sprinkle on lawns or garden areas. Using organic mulches and avoiding toxic chemicals is the only way to increase worm activity outdoors.

On the other hand, if you are intrigued by the notion of indoor composting with redworms, you will be pleased to learn that the whole process is fun, easy, and very inexpensive. Starting with a colony of 1,000 redworms, you'll be able to convert at least 60 pounds of kitchen scraps and old newspapers into about 15 pounds of nutrient-rich worm compost in less than half a year. Since worms and worm boxes are odor-free, you will be able to set one up in your utility room, basement, heated garage, or even in your kitchen. And don't worry: redworms dislike bright light and dry surfaces, they will not climb out of their comfortable boxes to go exploring. Feed them and they will stay put.

Vermicomposting Basics

There are several essential elements in vermicomposting:

  • a container
  • bedding
  • moisture
  • worms
  • food
  • maintenance
  • harvesting

It is easiest to build a worm box using either an old sweater box with a lid, or simply buy a dark-colored plastic storage container with a cover (usually $8 on average). Surface area is more important than depth -- and too deep a box can lead to complications. Look for a container approximately 2' x 3' x 1' deep. Drill or punch about 10-20 small holes (1/4" or less) around the side of the bin for aeration, about 1" - 2" up from the bottom.

Bedding is easily made by ripping up about five pounds of old newspaper (just the black and white sections) into one-inch wide strips. An easy method is to take several sheets of paper at one time, fold in half, and use scissors to start 1" long cuts about 1/2 to 1" apart. Then tear down the length using your initial cuts. Place the shredded newsprint in a bucket, and add about one to two gallons of water to soak thoroughly. Drain excess water and place in the worm box so that it's still fluffy. Worms need moist bedding to breathe through their "skin" and they also eat the cellulose fiber.

Now add your worms. Redworms only! (Biologists call them Eisenia foetida or Lumbricus rubellus.) Never use garden worms. Besides, you'll need about 1,000 worms -- or one pound in all. You can purchase worms through the mail or the Internet from a variety of vendors.

Feeding worms is the fun part of vermicomposting. Since redworms eat up to their own weight in food every day, your box will easily handle five pounds per week (but do not overfeed the box -- stop for a week or more if the worms cannot keep up with your supply). Feel free to include almost all fruits and vegetables, such as citrus and melon rinds, wilted lettuce, potato and carrot peelings, etc. You can also add coffee grounds and filters, tea leaves and bags, crushed egg shells, and houseplant prunings. Never add meat, fish, dairy products, or oils.

Add food by lifting up the bedding, depositing the scraps, and always covering it with the damp bedding. This will prevent any odors or fruit flies. Try to place food in alternate areas of the box. You shouldn't need to add any additional water -- but check every few weeks to make sure the bedding does not dry out. If the bedding gets soggy, tear up more paper and mix it in dry with the other bedding.

After about four-six months, the worm population will have grown remarkably and most of the food scraps and older bedding will have been converted into worm castings or vermicompost. There are many ways to harvest compost: hand separate worms from finished compost and put them back into the box with new bedding; or take out about three-quarters of the material and use in your garden -- add fresh bedding and start again with the remaining worm colony; or try pushing the material to one end of the box, add fresh, damp bedding to the other end, and only add food to the new section. Worms will migrate over in about one month -- then harvest your mostly worm-free compost.

Copyright 2009, Joseph M. Keyser

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