Are Earthworms Good for Plants? Benefits, Worm Castings and When to Worry
Are earthworms good for plants? Learn the real benefits of earthworms for soil and roots, what worm castings do, how to attract earthworms to your garden, and why invasive jumping worms are the one type you do not want.
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Dig into healthy garden soil and you will almost always find earthworms. Most gardeners see them as a good sign, and with good reason: earthworms recycle dead leaves into nutrient-rich castings, open up tunnels for air and water, and help roots grow deeper. But not every worm is a friend. Invasive jumping worms are spreading through gardens in many parts of the United States, and they do real damage.
This guide answers the question “are earthworms good for plants?” in practical terms. You will learn the main benefits of earthworms, what worm castings are, how to attract earthworms to your beds and lawn, when earthworms can be a nuisance, and how to recognize and contain jumping worms.
What Are Earthworms, Exactly?
Earthworms are not insects and not mollusks. They belong to the phylum Annelida, the segmented worms, as the University of Minnesota Extension notes. They have no eyes or lungs; they breathe through their moist skin, which is why they come to the surface on rainy days, especially in spring.
| Fact | Details | Source |
|---|---|---|
| Group | Phylum Annelida (segmented worms) | University of Minnesota |
| Length | Most garden earthworms are about 1 to 6 inches long | University of Minnesota, University of Wisconsin |
| Body | About 75 percent water | Washington State University |
| Soil pH range | Tolerate roughly pH 4.5 to 8.2 | Washington State University |
| Temperature | Temperatures around 85°F and below freezing are harmful | Washington State University |
| Number of species | The University of Wisconsin mentions over 7,000 species worldwide | University of Wisconsin |
Older articles, including the previous version of this page, often mention around 4,000 species. Current estimates are higher, and new species are still being described.
Are Earthworms Good for Plants?
Yes. In gardens, lawns and vegetable beds, earthworms are among the most useful soil animals you can have. The University of Minnesota describes them as “beneficial to gardens by aerating and fertilizing the soil.” The University of Florida IFAS Extension explains that their tunneling loosens and aerates the soil, and that their burrows provide paths for roots to grow and for water to soak in.
So when people ask “are earthworms good for plants?”, the honest answer is: almost always, with two exceptions. In fine turf, their castings can be a cosmetic nuisance, and invasive jumping worms damage soil instead of improving it. Both are covered below.
The Main Benefits of Earthworms
| Benefit | What happens | Source |
|---|---|---|
| Recycling organic matter | Earthworms feed on dead leaves and other organic matter and turn it into nutrient-rich castings | University of Florida IFAS |
| Better soil structure | Their activity builds soil structure and crumb | University of Florida IFAS |
| Aeration | Tunnels loosen the soil so air can reach roots | University of Florida IFAS, University of Minnesota |
| Water infiltration | Burrows help rain and irrigation water soak in instead of running off | University of Florida IFAS, University of Wisconsin |
| Root growth | Roots follow earthworm burrows deeper into the soil | University of Florida IFAS |
| Thatch breakdown | In lawns, earthworms help decompose thatch | University of Wisconsin |
These benefits of earthworms add up over time. A bed that is regularly mulched and rarely dug usually develops a dark, crumbly topsoil that drains well after rain yet holds moisture in dry spells. That is exactly the kind of soil vegetables, flowers and shrubs thrive in. For watering tips that suit healthy soil, see how often to water your garden.
What Are Worm Castings?
Castings are earthworm manure: the dark, granular material left behind after earthworms digest organic matter. Washington State University describes castings as worm manure rich in nutrients, and the University of Florida calls them a nutrient-rich humus.
- In the garden: earthworms deposit castings in their burrows and on the soil surface, enriching the topsoil for free.
- From a worm bin: red wigglers kept in a worm bin (vermicomposting) turn kitchen scraps into castings you can mix into potting mix or spread around plants.
- Bagged castings: sold as a soil amendment. Use them as part of your potting mix or as a top-dressing, not as a complete fertilizer.
Castings improve soil, but they are not magic. Healthy soil comes from regular additions of organic matter, not from one product.
Types of Earthworms in Your Garden
Washington State University describes three practical groups of earthworms:
| Group | Where they live | Role in the garden |
|---|---|---|
| Nightcrawlers | Deep, vertical burrows | Pull leaves down into the soil; create deep channels for water and roots |
| Shallow dwellers | Horizontal burrows in the topsoil | Mix and loosen the upper soil layer |
| Red worms (red wigglers) | Leaf litter, compost and manure | Ideal for compost piles and worm bins |
Washington State University also notes that nightcrawlers are the only earthworms that adapt to being moved to a new location. That is one more reason not to buy worms to “seed” your garden: if you improve the conditions, the earthworms already present in the area will usually move in by themselves.
How to Attract Earthworms to Your Garden
You do not need to buy earthworms. If you want to know how to attract earthworms, focus on food, moisture and shelter. Washington State University recommends these steps:
A leaf blower with a vacuum and shredding function makes it easy to turn fall leaves into earthworm-friendly mulch; see our best leaf blowers guide. For weed control without disturbing the soil, see how to keep weeds out of the vegetable garden.
Earthworms in Pots and Raised Beds
In raised beds, earthworms are just as welcome as in the ground. Beds that are filled with compost-rich soil and mulched every year usually develop a healthy earthworm population on their own, especially when the bed sits directly on the soil. See our guide on how to build a raised garden bed.
In containers, things are different. A pot has a limited amount of soil and organic matter, and drainage holes can let worms in or out. Garden earthworms that end up in a pot are usually harmless, but they are not needed: potting mix is already loose and airy. If you find many worms in a pot, check whether it stands directly on soil and whether the drainage holes are blocked. For container tips, see our container gardening guide.
Earthworms in the Lawn: Castings and Moles
In lawns, earthworms improve aeration and water infiltration and help decompose thatch, according to the University of Wisconsin. The downside is cosmetic: small mounds of castings on the surface can make fine turf look uneven, and earthworms can attract moles that dig in search of food.
- The University of Wisconsin states that there are no pesticides registered for earthworm control, and chemical control is not recommended.
- Rake, roll or brush out casting mounds when they are dry.
- Removing earthworms can lead to more thatch and more compacted soil, so the cure is worse than the problem.
Jumping Worms: The Earthworms You Do Not Want
Jumping worms are invasive earthworms that are spreading in many U.S. states. The University of Minnesota Extension explains that they change the soil texture so it looks like coffee grounds, strip the soil of nutrients and can kill plants.
| How to recognize jumping worms | Details (University of Minnesota) |
|---|---|
| Collar (clitellum) | Smooth, cloudy-white and flush with the body, about one-third of the way down from the head; European earthworms have a raised, saddle-like collar |
| Behavior | Wiggle vigorously and flip when disturbed; can move in an S-pattern like a snake |
| Size | About 1½ to 8 inches or more |
| Soil | Loose, granular soil that looks like coffee grounds in the top few inches |
| Life cycle | Hatch in late spring; adults lay eggs from August; adults live for only one season, but eggs survive winter |
What gardeners can do to contain them, based on University of Minnesota advice:
- Buy compost and mulch from suppliers who heat their piles to 131°F or above according to a pathogen-reducing process.
- When sharing plants, wash the soil off the roots and share bare-root plants where possible.
- Never release worms into the environment; throw unused fishing bait in the trash.
- The University of Minnesota notes that jumping worm eggs die when held at 104°F for three days, which is why properly heated compost is important.
- Clean soil from tools, boots and equipment before moving between gardens.
Signs of Healthy, Worm-Rich Soil
| Sign | What it tells you |
|---|---|
| Dark, crumbly topsoil | Plenty of organic matter and active soil life |
| Small channels and holes | Earthworm burrows that help water and roots |
| Casting piles on the surface | Earthworms are actively feeding |
| Mulch disappears over the season | Earthworms and other soil life are pulling it in |
| Rain soaks in quickly | Good structure and infiltration |
| Soil looks like dry coffee grounds | Possible jumping worms; check the collar of the worms you find |
Earthworms vs. Other Worms and Grubs in the Soil
Not every worm-like creature you dig up is an earthworm. Some are harmless, others are pests. This quick overview helps you tell them apart (widely accepted horticultural knowledge):
| Creature | What it is | Good or bad? |
|---|---|---|
| Earthworm | Segmented worm (Annelida) with a smooth, moist body and no legs | Good: improves soil |
| Jumping worm | Invasive earthworm with a smooth, cloudy-white, flush collar; thrashes when touched | Bad: degrades soil |
| White grub | C-shaped, cream-colored beetle larva with legs near the head | Pest of lawn and plant roots |
| Cutworm | Gray or brown moth caterpillar that curls up when disturbed | Pest: cuts off seedlings at soil level |
| Wireworm | Thin, hard, shiny yellow-brown beetle larva | Pest of potatoes and root crops |
| Red wiggler | Small red composting earthworm | Good in compost piles and worm bins |
If it has legs, it is an insect larva, not an earthworm. So when you wonder whether earthworms are good for plants, first make sure what you found really is an earthworm. For pests in the soil, see our garden insects guide and when potatoes are ready to harvest, where wireworms are a common problem.
Common Mistakes with Earthworms
| Mistake | Why it hurts | Better approach |
|---|---|---|
| Buying worms to add to the garden | Most species do not settle; you may introduce invasive worms | Improve conditions and let local earthworms move in |
| Frequent deep tilling | Destroys permanent burrows | Use a fork or no-dig methods |
| Leaving soil bare | Soil dries out and heats up | Mulch and keep plants growing |
| Using soil pesticides routinely | Can harm earthworms and other soil life | Use targeted, label-directed controls only when needed |
| Buying unheated compost or mulch | Risk of jumping worm eggs | Ask suppliers how their compost is heated |
| Trying to kill earthworms in the lawn | No products are registered; you lose the benefits | Rake out castings instead |
For pest control that protects soil life, see our guide on how to apply insecticide to plants safely and our garden insects guide.
What You Need
| Item | Why it helps | More information |
|---|---|---|
| Garden fork or hand tools | Loosens soil without destroying burrows | See our gardening tool sets guide |
| Leaf blower with vacuum and shredder | Turns fall leaves into mulch that feeds earthworms | See our best leaf blowers guide |
| Hose with gentle nozzle | Keeps soil moist in dry spells without compacting it | See our garden hose nozzle guide |
| Gardening gloves | Handling soil, compost and mulch | See our gardening gloves guide |
| Kneeling pad | Comfortable work in beds | See our kneeling pad guide |
| Compost bin or worm bin | Makes your own compost or worm castings | Use red wigglers in worm bins |
| Lightweight expandable hose | Keeps mulched beds moist in dry spells | See our expandable garden hose guide |
Frequently Asked Questions
Are earthworms good for plants?
Yes. Earthworms recycle organic matter into nutrient-rich castings, loosen and aerate the soil and create channels for roots and water.
What are the main benefits of earthworms?
Better soil structure, aeration, faster water infiltration, recycling of leaves and other organic matter, and nutrient-rich worm castings.
Are earthworms insects?
No. Earthworms are segmented worms in the phylum Annelida. They are not insects or mollusks.
How do I attract earthworms to my garden?
Add organic mulch, keep the soil moist, till less and reduce pesticide use. Earthworms move in when there is food and shelter.
Should I buy earthworms for my garden?
Usually not. Most species do not settle well in a new place, and you risk introducing invasive worms. Improve the soil and let local earthworms come to you.
What are worm castings?
Worm castings are earthworm manure: dark, granular material rich in nutrients that improves soil structure.
Are worms in potted plants bad?
Garden earthworms in a pot are usually harmless but not needed. Check whether the pot stands on soil and whether drainage holes are blocked.
Can earthworms damage plants?
Common garden earthworms do not. Invasive jumping worms can, because they strip the soil of nutrients and change its structure.
How do I recognize jumping worms?
Look for a smooth, cloudy-white collar that is flush with the body, about one-third of the way down from the head, and worms that thrash and flip when touched.
How do I get rid of earthworm castings in the lawn?
Rake, brush or roll them out when dry. There are no pesticides registered for earthworm control, and killing them removes their benefits.
Why do earthworms come out when it rains?
They breathe through their moist skin and often come to the surface on rainy days, especially in spring.
Do earthworms help compost?
Yes. Red wigglers are especially good at breaking down kitchen scraps in compost piles and worm bins.
Do earthworms eat plant roots?
No. Earthworms feed on dead and decaying organic matter such as fallen leaves, not on living roots. Root damage in the soil is usually caused by insect larvae such as grubs.
Can you have too many earthworms?
Not in a vegetable garden or flower bed. In fine lawns, many earthworms can mean more casting mounds and sometimes moles, but the benefits for the soil outweigh the nuisance.
Does tilling kill earthworms?
Tilling destroys their permanent burrows and can injure worms. Reducing tillage helps earthworm populations grow.
Final Thoughts
So, are earthworms good for plants? Absolutely, as long as they are the right kind. The benefits of earthworms include better soil structure, aeration, water infiltration and free fertilizer in the form of worm castings.
If you want to know how to attract earthworms, think like a worm: plenty of organic mulch, moist soil and as little digging and soil pesticide as possible. At the same time, stay alert for jumping worms, buy heat-treated compost and never release worms into your garden.
Sources: University of Florida IFAS Extension: earthworms in your landscape; University of Minnesota Extension: earthworms; University of Minnesota Extension: jumping worms; Washington State University Extension: earthworms; University of Wisconsin Extension: earthworms in turf.
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