Regional Gardening Reports :: National Gardening Association

In the Garden:
New England
September, 2005
Regional Report

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Worms will give you a steady supply of fertilizer in exchange for your food scraps.

As the Worm Turns

Worms are the best pets a gardener could ask for. They need no food other than scraps from the table, they make no noise, create no mess, take up little space, cost next to nothing for upkeep, and give us fertilizer for our plants. All you need is a worm bin for them to live in and a place to keep it that doesn't get too cold or too hot. Then instead of throwing away all those food scraps, you can recycle many of them in the worm bin. The worms benefit, you benefit, your plants benefit -- there's just no downside.

I occasionally get quizzical looks from people when I talk about keeping worms, but worm composting is no longer the fringe pastime it was back in 1982 when Mary Appelhof, a biologist and educator, started spreading the word about the enormous potential of the humble worm through her book, Worms Eat My Garbage. Over the years she got so many people hooked on the idea of using worms to recycle food waste that the book was reprinted 15 times and then revised by Mary seven years ago.

Now there are commercial worm composting (vermicomposting) enterprises that produce and sell worm compost, others that raise the worms for sale, and they are considered farming operations deserving of tax breaks in some states.

All the hubbub is because an earthworm can consume its weight in organic matter daily. Granted, a single worm doesn't weigh much, but a worm bin can hold several pounds of worms just waiting for leftovers. I don't weigh my worms or the quantity of food I give them; I just save food scraps from my family of four (no meat, bones, fish, or anything else smelly) and bury them in the worm bin every couple of days. I've never had any problems with odor, and I keep fruit flies from visiting by making sure the scraps are covered with worm bedding or a sprinkling of soil.

Redworms, also called red wigglers, are the best type of worm for composting in a worm bin. Eventually they will turn the leftovers into worm manure or "castings," rich in nutrients such as nitrogen, phosphorus, potassium, and calcium. Every three or four months or so, you need to separate this material from the bedding so you can mix it into potting soil or the garden. This is the only time-consuming routine of worm ownership, pretty nominal considering the only daily walk they require is the one you take to bring vegetable scraps to the basement or garage or wherever you locate your worm bin.

Numerous studies have demonstrated how the nutrients in worm castings improve plant growth, and in recent years they've turned up some other surprising effects. The castings apparently also contain microbes that can suppress diseases and increase plants' resistance to insects. We're sure to hear more about this benefit.

The Basics
To set up a worm composting system you need the following:
1. Red wiggler worms. You can order them by mail or harvest some from a friend's worm bin.
2. Bin. Many types are commercially available or you can fabricate your own. It needs to have drainage holes on the bottom.
3. Bedding. Shredded paper, coconut fiber, leaf mold.
4. Grit. Small amounts of soil or rock dust help the worms break down organic material.
5. Food. Most any fruit or vegetable, bread, cereal, coffee grounds, tea bags and leaves, eggshells. Avoid meat, bones, large amounts of citrus rinds, pet waste, and anything nonbiodegradable.

There are lots of ways to fine-tune the process but basically you place the bedding in the bin, add the worms, then feed them your food scraps regularly. The worms will digest the scraps along with some of the bedding material and produce castings. As the castings build up, you need to separate them out for mixing into potting soil or the garden or spreading on the surface of your container plants. Then add more bedding to the bin to keep the process going. Good bins have drainage spouts so you also can collect the liquid as it accumulates and use it to fertilize your plants.

I look at worm composting as a way to expand the recycling process that goes on outside in my compost piles. It's also the best option in winter when the outdoor pile is too frozen to bury scraps.

Mary Appelhof died last spring, but it's easy to imagine you're having a conversation with her when you read her book. She devoted 25 years to working with worms, and had enormous respect for the important role they play in recycling waste. Thanks to her, so do many of us.

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