If you’ve noticed small mounds of soil in your garden, you might be wondering what’s causing them. These mounds can appear suddenly and disrupt the smooth surface of your lawn or garden beds. They may be a sign of burrowing animals, insects, or soil conditions.
Understanding the causes of these small soil piles is the first step in addressing the issue. In this guide, we’ll explore the common reasons behind these mounds and effective solutions to keep your garden healthy and tidy.
Common Causes of Small Mounds of Soil in the Garden
1. Earthworms and Their Castings
One of the most common causes of small soil mounds is earthworm activity. These beneficial creatures create small, granular piles called castings as they tunnel through the soil.
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Signs of earthworm mounds: Tiny, rounded mounds with a grainy texture.
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Are they harmful? No, earthworms improve soil aeration and fertility.
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Solution: Simply rake the castings into the soil or let them break down naturally.
2. Ant Hills
Ants create small mounds of soil when they build underground tunnels. These mounds can appear in lawns, flower beds, or near sidewalks.
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Signs of ant hills: Dry, loose soil piled up around a small entrance hole.
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Are they harmful? Some ants aerate the soil, but others may attract aphids or bite.
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Solution: Sprinkle diatomaceous earth around the area or use ant bait to control infestations.
3. Mole Activity
Moles are burrowing mammals that create raised tunnels and cone-shaped soil mounds. They dig underground in search of worms and insects.
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Signs of mole mounds: Larger, conical mounds with disturbed soil nearby.
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Are they harmful? Moles don’t eat plants but can damage roots while tunneling.
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Solution: Use castor oil repellents, remove their food source, or install mole traps.
4. Voles and Their Runways
Unlike moles, voles create surface tunnels and push soil out of the way, forming small mounds. They may also chew plant roots and bulbs.
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Signs of vole activity: Shallow runways with small, scattered soil piles.
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Are they harmful? Yes, voles damage plant roots and garden beds.
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Solution: Set up live traps or use natural predators like owls to control their population.
5. Gophers and Their Mounds
Gophers dig deep burrows and create horseshoe-shaped mounds of fresh soil. These rodents are larger than moles and can damage plants by eating roots.
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Signs of gopher mounds: Large, crescent-shaped piles with a plugged entrance hole.
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Are they harmful? Yes, gophers can destroy lawns and gardens.
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Solution: Use gopher traps, repellents, or plant gopher-resistant plants like daffodils.
6. Cicada Killers and Ground Bees
Certain insects, like cicada killer wasps and ground bees, dig small burrows and leave behind loose soil mounds.
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Signs of insect burrows: Small mounds with a visible hole in the center.
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Are they harmful? Most are harmless pollinators, but some wasps can sting.
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Solution: Leave them alone if possible, or use soapy water to discourage nesting.
7. Poor Drainage and Soil Settling
Sometimes, small soil mounds form due to poor drainage or soil settling after heavy rain. When water collects in certain areas, it can cause soil displacement, leading to uneven surfaces.
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Signs of drainage issues: Irregular mounds after rain or in low-lying areas.
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Are they harmful? Not directly, but they can make your garden uneven.
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Solution: Improve drainage by adding organic matter or installing French drains.
How to Get Rid of Small Soil Mounds in the Garden
Once you identify the cause of the soil mounds, you can take appropriate action. Here are general solutions to keep your garden mound-free:
1. Rake and Level the Soil
For harmless mounds like worm castings or soil settling, simply use a rake to level the surface. This will keep your lawn even and prevent bumps.
2. Remove Food Sources for Pests
Moles and gophers dig in search of food. Reduce their presence by controlling grubs, earthworms, and insect larvae in your soil.
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Apply beneficial nematodes to reduce grub populations.
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Use milky spore powder to eliminate beetle larvae.
3. Use Natural Repellents
If burrowing animals are the problem, try natural deterrents:
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Castor oil for moles and gophers.
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Garlic or cayenne pepper for voles and ants.
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Diatomaceous earth for insect control.
4. Install Physical Barriers
To keep animals from burrowing, install underground mesh or fencing around your garden. A hardware cloth barrier can prevent gophers and voles from entering plant beds.
5. Trap or Relocate Pests
For severe infestations, use humane traps to catch and relocate moles, voles, or gophers. Check local regulations before relocating wildlife.
6. Improve Soil Health
Healthy soil is less attractive to pests. Enhance your garden’s soil by:
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Adding compost to improve structure.
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Avoiding overwatering, which attracts insects and rodents.
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Keeping grass short to discourage ground-dwelling animals.
Preventing Small Soil Mounds in the Future
To prevent small mounds from forming again, maintain a consistent garden care routine.
1. Regular Lawn Maintenance
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Mow the lawn regularly to discourage moles and voles.
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Rake leaves and debris to reduce hiding spots for pests.
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Keep the soil evenly moist but not soggy.
2. Encourage Natural Predators
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Attract owls, hawks, and snakes to control rodent populations.
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Encourage beneficial insects like ladybugs and lacewings.
3. Monitor Soil and Drainage
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Check for signs of poor drainage and improve water flow.
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Fill in low spots with topsoil to prevent pooling water.
Frequently Asked Questions
1. Are small soil mounds always a sign of pests?
No, some mounds are caused by earthworms, insects, or soil settling rather than harmful pests.
2. How can I tell if mounds are from moles or gophers?
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Mole mounds are round and volcano-shaped.
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Gopher mounds are crescent or horseshoe-shaped.
3. Can I use chemical pesticides to get rid of mounds?
It’s best to use natural solutions first. Chemical treatments can harm beneficial soil organisms.
4. Will grass grow back over ant hills?
Yes, but it’s best to flatten the mound and reseed the area for even growth.
5. How do I stop earthworms from making castings?
You can’t eliminate earthworms, but frequent raking can spread their castings evenly.
Small mounds of soil in the garden can be caused by earthworms, ants, moles, voles, gophers, or drainage issues. Identifying the source of the mounds is key to finding the right solution.
By raking, improving soil health, removing food sources, and using natural repellents, you can maintain a smooth and healthy garden. Regular maintenance and monitoring will help prevent future soil mounds, keeping your landscape in perfect condition.