We recently received another question from a reader about worms and gardens, which is a perennial topic of concern among our readers. If you are into gardening, you have to pay attention to worms. Our reader found some worms under a dead plant near her house. A couple of the worms were somewhat long, around six inches in length, but one of them was short and plump, at least relative to the long worms. Thinking the worms would be good for the soil, the reader moved them into her garden. Upon doing this, it occurred to the reader that she might have introduced something into her garden that isn’t conducive to its health. After all, she found the worms under a dead plant, and she worried that the worms might have caused this plant’s death. More generally, the reader was wondering, what worms are suitable for one’s garden?

A lot of different ground is covered in our reader’s email, so we’ll focus on some general information about worms and gardens. In doing so, we hope to answer our reader’s questions and provide some helpful advice to gardeners interested in worms.

With respect to the reader’s specific situation, we of course can’t say exactly what type of worm our reader found, if indeed she found a worm at all. (It is extremely common for people to mistake creatures like caterpillars and millipedes for worms.) For this reason, we don’t know if they will be harmful to her garden, but we suspect that they won’t be. Why? Because the soil will do more damage to the worm than the worm will do damage to the soil, generally speaking. If you introduce a worm into your garden and it is not “meant” for your garden, the worm likely won’t wreak havoc on your garden. It will simply leave your garden or die trying. For example, if you were to put red worms, which are commonly used for composting, in your garden, they simply won’t live there. Their way of life, in other words, is not conducive to most garden soils. But red worms won’t ruin your garden either.

Unfortunately, the same can’t be said of every creature you might put in your garden. There are a number of caterpillar species, for example, that can damage trees and plants, and it would be best to keep these away from your garden. Of course, not all caterpillars are harmful to plants, and even if they are harmful, they won’t be damaging to every type of plant. So, whether or not our reader introduced a creature into her garden that will cause problems is simply something we cannot comment on: it depends on what she put into her garden, and it also depends on what is in her garden. This is a vague answer, but it is vague by necessity.

One thing we can say with certainty is this: if our reader found earthworms, then she definitely didn’t cause any problems by putting them in her garden. Earthworms dig tunnels through soil, allowing air and moisture to more easily travel through it, increasing the soil’s health. Earthworms also produce waste, called castings or vermicompost, and this waste is basically a super vitamin for soil and the plants that grow in it. Plants grow quickly and remain healthy in soil rich with worm castings. Earthworms are nothing but a boon for your garden, and indeed their presence in your garden is a sign of its overall health.

Fortunately, based on the reader’s description, the creatures she found could very well be earthworms. Earthworms that are about six inches long are very common, as are shorter and plumper ones (because earthworms come in a number of sizes).

In general, putting worms in your garden is not harmful. They will either help maintain the health of your garden, or else they will merely abandon your garden without doing harm. However, not all creatures are benign at worst, so it is best to exercise some caution when introducing a worm or worm-like creature into your garden.