I was cleaning up my garden for winter and I noticed a lot of earthworms. Is this a problem or a good thing? SW

Up until about March of this year, the Master Gardeners taught classes in elementary schools throughout Tulsa County. That of course changed because of Covid-19. But, my favorite class to teach to the kids was our class on earthworms. We affectionately call it Worms to the Wise.

In this class not only do the kids learn a lot about worms, but there is a hands-on portion that is always fun. Some kids refuse to touch the worm while others can’t get enough and want to take the worms home.

One of the main take-aways we try to leave with the kids is how important worms are to our environment and our ability to grow plants successfully. Since you are reading this and I am not about to lay a worm on your forearm, there probably won’t be any screaming, so let’s just talk about worms…earthworms in particular.

So, what’s going on below the surface with the worms that make them beneficial for our gardens and our general eco-system?

First of all, worms are constantly eating and digging, primarily in the top 18 inches of the soil. The worm’s primary digging part is its mouth or prostomium. As the worm eats and digs, they make tunnels. These tunnels accomplish several things.

The tunnels that the worms dig loosen up the soil and reduce compaction. Loose soil is a better growing environment than hard compacted soil. In addition, the tunnels are great pathways to allow water and air to get down into the soil. Good garden soil is about 50% mineral and organic content, 25% air and 25% water. The tunnels from earthworms help introduce air and water into the soil.

Anything that goes into the worm as food, comes out the other end as fertilizer. We call this worm excrement castings. Worm castings are prized by gardeners and you can actually by bags of worm castings as a supplement for your garden. Earthworm castings are higher in nitrogen, phosphorus, and calcium that typical surrounding soil so as they work their way through your soil, they are leaving it better than when they arrived.

There is also the issue of soil pH. Soil that has worked its way through an earthworm comes out with a neutral pH. If you have high pH soil or low pH soil, earthworms are working on your behalf to return that to a neutral, more appropriate growing environment.

In addition, earthworm castings are high in beneficial microbes that help decompose plant residue. This helps to build up your topsoil layer.

Now let’s talk a little about earthworm biology to help better understand our underground friends.

Earthworms don’t have bones or a skeleton which should come as no surprise to anyone that has ever handled a worm. Their body is comprised of segments. Up front there is a mouth, a very small brain, 5 hearts, and other organs. As we move down the worm, we can see a band called the clitellum which is a sexual organ only adults have, Worms are neither male nor female but it does however take two to tango. The rest of the worm contains its intestines.

While we are here, let’s dispel a myth. If you cut a worm in half, you will not end up with two worms. You will likely just end up with a dead worm. It is possible that if the separation happens in the right place, the worm could repair the damage to its intestines, but a lot of things would have to go right for that to happen which begs the question… why?

Worms also do not have lungs; they breathe through their skin. To accomplish this, their skin must remain moist. Most of us have seen worms on the driveway, sidewalk, or street after a rain. This is because the soil is saturated from the rain and the worms cannot breathe. When they come up for some air, they can get confused and end up on the pavement. If they are there long enough, they dry out, and since their skin needs to be moist for them to breath, they don’t usually make it back to the soil. I told this to my wife a few years ago and now our neighborhood walks include pauses to pick up worms in the street to return them to a more suitable environment. Yes, after a rain our walks take longer.

To help them move, earthworms also have tiny hair-like bristles called setae. As the worms extend themselves in length, they can grab hold with these setae and bring up the rear so to speak. If you have ever seen a bird trying to pull a worm out of the ground, those little setae are working overtime to keep that from happening.

I mentioned earlier that the Master Gardeners teach classes in elementary schools about worms and other horticultural topics. Since that is all on pause right now, we put together a series of activities for kids on our website we are calling Science in a Snap. Each activity includes a video, a trivia game, and some hands-on activities. Until we can get back in the classroom, check out these fun ways to learn about trees, soil, pollinators, and yes worms.

The bottom line: worms are great for your garden.

You can get answers to all your gardening questions by calling the Tulsa Master Gardeners Help Line at 918-746-3701, dropping by our Diagnostic Center at 4116 E. 15th Street, or by emailing us at mg@tulsamastergardeners.org.