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Master Gardener: Here's why you want plenty of worms in your garden
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Master Gardener: Here's why you want plenty of worms in your garden

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I was digging in my garden the other day and I found quite a few earthworms. Is this a good thing or a bad thing? LK

It’s hard to understate the importance of worms in your garden. In fact, in 1881 Charles Darwin wrote “It may be doubted if there are any other animals which have played such an important part in the history of the world as these lowly organized creatures.”

So, let’s talk about some of the benefits worms bring to your garden.

First of all, worms are diggers. To dig, they use a part of their body called the prostomium. The prostomium is kind of like a large upper lip that helps to dig and then move the soil into their mouths. Worms like to dine on decaying organic matter in the soil. After digesting this organic matter, they deposit their nutrient rich excrement (also known as castings) back into the soil.

If you’ve ever been to an organic garden center, you will likely find bags of worm castings for sale since these castings make great fertilizer. It is estimated that each worm can produce the equivalent of 1/3 pound of top-grade fertilizer each year, but worm castings are not the only benefit.

While the worms are digging and dining, they are also loosening up the soil. Loose soil makes a much better growing environment for your plants. Loose soil is less compacted which allows water to better enter the soil and less compacted soil is also better at holding more water for a longer period of time. If you have a yard that is primarily clay-based soil, you know that water tends to pool and run off these soils while more sandy soils better absorb the water. Good garden soil is about half solids, 1/4 water and 1/4 air, so worms are vital to helping the soil become better receptive to water and air. This digging also helps turn the soil as the worms help bring soil to the surface and transfer nutrient rich soil deeper into the ground.

As the worms dig, they are also making it easier for the smallest of roots to grow into and through the tunnels they leave behind. Imagine you are a small root trying to grow. Is it going to be easier for you to push through hard, compacted soil or follow the trail of a worm who has left fertilizer behind their path?

I was careful there not to say his or her path because worms are both/and however, it does take two worms to reproduce. Earthworm populations can vary due to a variety of conditions, but it would not be unusual to find 50-300 earthworms in a square yard of cropland with even more in healthy organic soil. We have all likely seen a football field. Well, an area of land the size of a football field can support close to 1 million worms. Did someone once count this? I doubt it, but that is still a lot of worms.

In this part of the world, we measure our worms in inches, but in South Africa, worms have been measured up to 22 feet in length. It is said that if you are standing above one of these rather large worms, you can actually hear them moving underground. I would put that in both the cool and creepy categories.

The Tulsa Master Gardeners teach a class on worms for students of elementary school age. We take our presentation and several containers of worms to various elementary schools each year and it is one of my favorite classes to teach. We do miss doing that in the last year due to COVID-19 restrictions. Hopefully this fall we will be able to resume these classes.

People ask me “why is the worms class my favorite” and I always say “because no one screams in the class about seeds.” And it’s true. Irrespective of the grade level, the classes typically self-divide into two contingencies. There is the “all about it” group who hold the worms and participate in the scientific exercises and there is the “not in this lifetime” group that wants no part of it. And yes, sometimes there is screaming at the sight of the wigglers, but at least they all leave knowing the importance of worms to our ecosystem, even if they never want to touch or hold one.

My wife and I like to go on daily walks in our neighborhood. However, if our walk happens to occur after a rain, these walks take much longer since we obviously have to help wayward worms in the street get transported back to a nearby lawn. I’m sure that more than one neighbor has discussed our sanity on this issue, but we would do the same for them… probably.

If you are an elementary school teacher or know an elementary school teacher, you/they can sign up on our website to be notified when we will begin going back out into the schools teaching classes once again. These classes not only cover worms, but we also have classes on seeds, trees, soil, insects, pollinators, and more. Just go to and click on School Program. And, if you need to add worms to your garden, you can rescue some that are meant for fish bait at area sporting goods stores.

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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


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