by Rob Sproule
Of the humble earthworm (Lubricus terrestris), Charles Darwin said it best: “It may be doubted whether there are many other animals which have played so important a part in the history of the world, as have these lowly organized creature.”
Native to Europe but introduced worldwide, earthworms are vital to the health of our soil. A square acre of healthy earth has about 50,000 worms working hard to keep it that way, and there are things that we can do to ensure that they flourish in our home gardens.
Nicknamed “Nature’s plow”, worms are the humble workhorses of the garden. Their tube-like bodies tunnel through soil, soft or hard, loosening it as they go. Plants’ delicate root systems thrive in well aerated soils where they can expand freely into air pockets, leading to healthier plants and better harvests.
Besides loosening compacted soil, worms leave castings behind that are so stuffed full of nutrients they have become a valued ingredient in many organic fertilizers. Called Vermicompost, the castings contain about 7 times the nutrients as common compost, including micronutrients that plants can’t get anywhere else.
The castings act like sponges, soaking up water and retaining it far longer than soil. Having ample worm castings increases overall water retention in the soil and, in doing so, will help plants better tolerate droughts.
Bacteria living inside worms’ bodies have the ability to actually break down some toxic chemicals that accumulate in garden soil. Their bodies actually detoxify some fungicides and pesticides, although it’s often at significant cost to the worm’s health.
Worms have become big business in recent years, with more people worm-composting and looking for worm casting enriched organic fertilizers. You can buy worms for the garden, just as you would for your tackle box, but you really don’t need to. If you keep a worm-friendly garden, you’ll get them naturally. If your garden isn’t worm friendly, they’ll die or leave no matter how many you buy.
Nurturing your Worms
Having a healthy worm population can take your veggie garden from fair to flourishing. It’s easy to make your garden inviting to worms if you think like a worm!
Worms love moist soil that’s amply loaded with yummy rotting organic matter. Let a 3′ by 3′ square in the garden accumulate leaf litter and, if you’re keen, bury some kitchen scraps a spade depth below the surface. Worms don’t travel far, so make sure the plot is adjacent to the garden you want them to move into.
Keep your garden consistently watered; parched soil is dangerous to their moist bodies. Try to keep digging and, especially, roto-tilling to a bare minimum. Once you’ve established your squiggly population, protect it by not spraying harsh chemicals into the garden.
Earthworms Invasive in Forests
While they’re beneficial in the garden, it’s important to keep them in the garden and out of our forests. Earthworms damage Albertan forests by breaking down leaf litter, which many other species of plants need to survive, faster than usual. Worm-invaded forests lose a lot of biodiversity at the forest floor level.
All of Alberta’s native earthworms were wiped out during the last Ice Age, and our forests evolved to flourish without them. Now that we’re widely importing earthworms from Europe, they’re wriggling their ways back into forests that don’t need them.
The worms in your garden are not going to ravage the nearby forests. Left alone, they will rarely travel more than 10-20 metres in a year, and rarely pass artificial barriers like roads. If you use them in your tackle box, however, than you’re probably giving them a free ride into pristine forests.
Earthworms have invaded our forests from fishing, not gardening. Anglers, please never throw your unused wriggling bait into the forest. You’re actually aiding and abetting an invasive species.