Organic Gardener

Earthworms - those fertilizing, rototilling wonders in your soil

Author: Susan Harris

The many virtues of the lowly earthworm have long been recognized, with Cleopatra famously declaring them to be sacred - they benefited Egyptian farmers that much. Then Charles Darwin deemed them worthy of 40 years of study and wrote a whole book about them.

Here in North America the original earthworms were killed off during the last Ice Age, leaving very little of the land suitable for farming.  The few worms that did survive are poor soil-builders and wiggle off to undisturbed parts at the first sign of farming.  That's why America's organic farmers have turned to European earthworms to make the soil fertile to be productive.

So how do earthworms help?  Where to start!  First, their castings are high-test compost packed with nutrients.  And by burrowing through the soil they leave passageways for air and water, which relieves compaction and improves drainage.  As if that isn't enough, earthworms discourage harmful insects and disease while promoting beneficial soil bacteria.  Studies have shown that the introduction of earthworms to farmland has resulted in yields increasing by as much as 20-fold!

Don't have em'? How to get 'em
In a typical quarter-acre garden there could be as many as 125,000 earthworms, or there could be none. Though gardening will usually attract earthworms, the use of synthetic fertilizers, herbicides and insecticides makes the soil too toxic for them to survive, much less thrive.  So if your soil is missing these miracle critters, the first step is to stop using toxic products.  Then if you just spread a 2-3 inch layer of organic matter on top of the soil ever year (keeping it away from the stems of your plants), worms will magically appear. They come for the delicious organic-matter dinner and stay to reproduce like the hedonists they are.

Leafmold, which is simply chopped-up and partially decomposed leaves, may be the best earthworm meal there is and it's definitely my favorite mulch. My town collects our leaves in the fall, chops them up, and offers them back to us the following spring as leafmold, and if your doesn't do that, now's a good time to make a pitch for such a win-win recycling program.

Another option is to jump-start your garden's earthworm population by ordering them in egg form through the mail. Just scatter them on the ground and in about 3 months they're all grown up, making babies, and working hard to improve your soil.

For more information:

• Wikipedia.
• The very readable The Earth Moved: On the Remarkable Achievements of Earthworms, by Amy Stewart.

Photo by Amy Stewart.

Help us to spread the word:

Susan Harris

Susan is a Gardening Coach, GardenRant blogger, Master Gardener, garden writer, and activist for urban and suburban greening. She is an active writer and contributer to the gardening community.
Read more about Susan.

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