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Those small mounds of fine soil appearing across your lawn are the work of ants. While they’re not directly harmful to grass, ant hills create an uneven surface, make mowing difficult, and can smother grass beneath them if left unchecked. Here’s how to deal with them effectively.
Why Ants Build Hills in Lawns
Ants excavate soil to create underground nests, and the displaced earth has to go somewhere. They deposit it on the surface, creating those characteristic mounds. The fine, powdery texture comes from ants processing soil particles as they dig.
Yellow meadow ants are the most common culprits in UK lawns. They prefer dry, undisturbed soil and south-facing slopes. Black garden ants also build hills but tend to nest in cracks, under paving, and at lawn edges rather than in the middle of turf.
Ant activity peaks in summer when colonies are most active. You’ll notice more hills appearing during warm, dry spells when the soil is easy to excavate.
The Problems Ant Hills Cause
The hills themselves are the main issue rather than the ants. Each mound smothers the grass beneath it, creating a bare patch. As mounds multiply, your lawn becomes increasingly uneven.
Mowing becomes frustrating when your mower scalps the tops of ant hills while missing the grass in between. The exposed soil on scalped mounds is perfect for weed seeds to establish. Over time, what started as a few small hills can turn into a seriously bumpy, patchy lawn.
The good news is that ants don’t eat grass roots or damage turf directly. Unlike leatherjackets or chafer grubs, they won’t destroy your lawn from below. The damage is purely from soil deposition on the surface.
Quick Fix: Brush Them Flat
The simplest solution is regular brushing. Use a stiff brush or besom broom to scatter the mounds across the lawn before mowing. This redistributes the fine soil into the grass where it actually benefits the lawn as a light topdressing.
Do this when the soil is dry. Wet ant hills smear across the grass and create a mess. A quick brush before each mow during summer keeps hills manageable and prevents them building up.
This doesn’t eliminate the ants or stop new hills forming, but it manages the visible problem effectively. For many gardeners, regular brushing is all that’s needed.
Encourage Ants to Move
Ants prefer dry, undisturbed conditions. Making your lawn less hospitable encourages them to relocate without using chemicals.
Heavy watering floods ant nests and persuades colonies to move somewhere drier. Soak affected areas thoroughly several times over a week or two. This works best combined with any of the other methods.
Regular aeration disturbs the soil structure ants rely on. Spiking or hollow-tining disrupts tunnels and makes the lawn less attractive for nest building.
Keeping grass healthy and thick through proper feeding creates a denser root zone that’s harder for ants to excavate. A vigorously growing lawn also recovers faster from any damage.
Ant Powder and Treatments
If brushing and cultural methods aren’t enough, ant powders and baits provide more direct control. Several effective products are available from garden centres.
Ant powders work on contact and are applied directly to hills and nest entrances. The ants carry particles back into the nest, spreading the treatment through the colony. Results typically show within a few days.
Ant baits use a slow-acting poison that worker ants take back to feed the queen. This approach takes longer but can eliminate entire colonies rather than just the ants you see on the surface.
Follow product instructions carefully. Most ant treatments are harmful to other insects too, so avoid applying near flowering plants where bees are active.
Natural Ant Deterrents
Various home remedies are suggested for ant control, with mixed results.
Pouring boiling water into nest entrances kills ants on contact but rarely reaches the queen deep underground. You’ll kill some workers but the colony usually survives and rebuilds.
Diatomaceous earth sprinkled around hills damages ants’ exoskeletons and dehydrates them. It’s non-toxic to pets and children but needs reapplying after rain.
Strong-smelling substances like peppermint oil, cinnamon, or citrus peel are said to deter ants. They may discourage ants from specific spots but won’t eliminate established colonies.
Nematodes marketed for ant control can reduce populations but results are inconsistent. They work better on some ant species than others.
Living With Lawn Ants
It’s worth considering whether ant hills are actually a problem that needs solving. Ants are beneficial insects that aerate soil, recycle organic matter, and provide food for birds.
In wilder garden areas or meadow lawns, ant hills add character and support biodiversity. Yellow meadow ant hills in old grassland can be centuries old and are protected in some conservation contexts.
For formal lawns where appearance matters, control makes sense. For more relaxed gardens, regular brushing to prevent mowing problems might be all you need. The ants themselves aren’t harming your grass.
Repairing Ant Hill Damage
Once you’ve dealt with the ants, you may have bare patches where hills smothered the grass. These repair easily with a bit of seed.
Rake the area to remove dead grass and loosen the surface. The fine soil from ant hills actually makes a decent seedbed. Scatter grass seed, rake lightly, and keep moist until germination.
For advice on patch repairs, see our guide to fixing bare patches. The technique is the same regardless of what caused the damage.
If your lawn has become seriously uneven from years of ant activity, you may need to level it properly with topdressing rather than just treating individual spots.
Preventing Future Problems
A thick, healthy lawn is your best defence against ant problems. Dense turf is harder for ants to excavate and recovers faster from any disturbance.
Thickening thin areas removes the bare, dry soil that ants prefer. Regular feeding promotes strong growth that competes with ant activity.
Keep on top of brushing during summer when ants are most active. A quick sweep before mowing takes seconds and prevents hills accumulating to problem levels. For more lawn pest solutions and maintenance tips, explore our complete lawn care library.
Healthy, well-fed grass recovers quickly from ant damage and other stresses. Our Year Round Lawn Treatment Bundle provides everything your lawn needs across all four seasons, keeping it thick and resilient all year.
