Friday, August 27, 2010

Earthworms - Wriggling Wonders of the Garden

Earthworms are the intestines of the soil. – Aristotle

One of the most memorable questions that I ever received from a fellow gardener was from the gentleman who called me with his earthworm problem. “What can I do to get rid of all of these awful earthworms,” he said. “They’re all over the place.”

Although most gardeners would love to see slimy, wriggling earthworms, rolling around in their soil, this gentleman saw them only as a nuisance. Such is the case with many garden critters, which are shunned at first sight and sometimes even eradicated from a yard long before the gardener takes the time to learn their bountiful benefits.

There is no doubt that earthworms are slimy little critters. Nevertheless, if you have earthworms in your yard, you should feel lucky. If you could create a miniature little robot that could aerate your soil by creating passageways for air and water, all the while adding valuable nutrients to the soil, wouldn’t you do it? Too late. Nature has already created this creature and we have named him “earthworm”.

Like many creature’s, an earthworm’s primary activity is eating and eliminating what it eats. But in the case of the earthworm, the old adage of “garbage in, garbage out” isn’t very accurate. With earthworms, what they eliminate, called castings, are pure gold to your garden soil.

You don’t have to go to the extent of Cleopatra who supposedly considered earthworms so indispensable to the agricultural economy of ancient Egypt that she declared them sacred, subjecting exporters to the death penalty. But you should definitely roll out the red carpet for these creatures by giving them what they like – a nice layer of damp fallen leaves or other organic matter.

In my continuing effort to learn more about “environmentally friendly” landscaping, I decided to see what else I could find out about earthworms.

Environmental benefits of earthworms
  • Earthworm poop peps up your plants. Earthworms eat microorganisms in the soil. As the organic matter passes through their system, it is fragmented and inoculated with other microorganisms. The resulting feces or casts contain nutrients and organic matter that is more readily taken up by plants.
  • Earthworms help stir things up! A large proportion of soil passes through the guts of earthworms, and they can actually turn over the top six inches of soil….in about ten to twenty years. But in the process of moving dirt around, they can bring essential nutrients back to the top layers of the soil that had leached down.
  • Earthworms help prevent erosion. Earthworms make soil more porous as they move through it. Some species make permanent burrows deep into the soil. These burrows can remain long after the worm has died, and can be a major conduit for soil drainage, particularly under heavy rainfall. At the same time, the burrows minimize surface water erosion.
  • Earthworms help soil retain moisture. By fragmenting organic matter, and increasing soil porosity, earthworms can significantly increase the water-holding capacity of soils.
  • Earthworms help prevent water pollution. By allowing more water to seep into the soil, earthworms help prevent pollution by minimizing runoff.
  • Earthworms provide channels for root growth. The channels made by deep-burrowing earthworms are lined with readily available nutrients and make it easier for roots to penetrate deep into the soil.
  • Earthworms help feed local wildlife. Earthworms are a favorite food of many bird species and other friendly garden predators such as toads and turtles.
If you see earthworms in your yard, then it is a good sign that you have a somewhat “healthy” garden. Earthworm populations tend to increase in areas with richer organic matter levels and decrease with soil disturbances, such as tillage and potentially harmful chemicals. If you would like to attract MORE earthworms, here are a few tips:
  1. Avoid using chemicals. Pesticides are one of the biggest threats to earthworms today. Many common pesticides, even "organic" pesticides, kill earthworms, some with mortality rates as high as 100%. Chemicals that are used to kill Japanese beetle grubs, for example, also kill earthworms. Some chemical fertilizers, herbicides, and fungicides can also kill earthworms.
  2. Avoid unnecessary cultivation. Studies have found a direct correlation between the frequency of cultivation and the number and size of earthworms: the more frequently the ground is cultivated, the fewer and smaller the worms. When possible, cultivate beds by hand or with a digging fork. Hand cultivation has a significantly lower mortality rate for earthworms than machine cultivation.
  3. Add compost and other organic matter to your soil. If you make your own compost, you may see earthworms in your compost pile. Spreading a thick layer of finished compost on new garden beds, or digging it in when you plant, is a great way to improve your soil, produce healthier plants, and attract worms, all at the same time. If you don’t have a compost pile, you can feed the worms by adding certain food scraps such as vegetable peelings and coffee grounds directly to your garden either in shallow holes or under layers of mulch.
  4. Add mulch. Worms are easily killed by surprise frosts on unprotected soil in spring and fall. Mulch provides an insulating blanket that can help protect them from the cold. It also helps keep soil cool and moist in the summertime when worms are typically driven deep underground to hide from warm temperatures and dry soils. Organic mulches such as straw and shredded leaves are also favorite worm foods.
*Many of the facts for this article were found from this source: The Living Soil: Earthworms, NRCS website


  1. Great informative article. Love my garden worms.

  2. As avid 'composter' and friend of all critters, including earthworms (which aren't slimy when I touch them), I thank you for this article. I never thought about worms' role in soil erosion although I noticed of course that our small green patches are doing better during rainstorms because plants grow healthier (and why do plants get healthier? so it's just a matter of thinking it through, thanks!). This helps to prevent runoff and consequent increased water pollution as mentioned in the article. However, any stable toxins will stay in the soil or leak out eventually.

  3. This is a very informative post about earthworms. I absolutely agree that earthworms are some of our garden's bestfriends! Our lawn and garden are beautiful not just because we know how to take care of them but because of our little friends such as earthworms as well. Thanks for sharing this very educational and interesting post!

  4. I am a novice gardner with two small children. My time is limited however I would very much like to grow vegetables this year. Last year we were successful with about 5 tomato plants, however I did not have time to tend to much of my garden, so I put newspaper down and mulch on top. It was great weed control, but now I am trying to figure out what to do with it. I have started to weed out the crab crass and am finding lots of worms (my 3 yo daughter is very excited too). The crab grass under the decomposing newspaper is easy to pull out, but I am not sure what to do with the paper or the mulch. Can I just turn it into the earth, add some more soil and compost and plant?

  5. I wanted to clarify that the much I used was untreated shredded wood type.

  6. Yes, as long as the the mulch is untreated it should be fine to turn it into the soil. Most newspapers are printed with soy based ink and can be added to compost piles or worked into the soil.


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