Learning Center / Lawn problems
How can you tell if your lawn is compacted?
Water that puddles or runs off, ground that is hard to push a screwdriver into, and grass that stays thin along paths and play areas are the usual signs. In Northern Virginia's clay, most lawns compact a little every year.
- By David Obeid, founder
- Reviewed
- 4 min read
The short answer
What does compacted soil do to a lawn?
It squeezes out the air and space that roots, water and nutrients need, so the grass stays shallow-rooted, thin and stressed. A compacted lawn struggles in summer heat, drains poorly after rain and leaves room for weeds.
The clay-heavy soils across Arlington, Falls Church and the rest of Northern Virginia compact under foot traffic, mower wheels and summer heat. Lots that were packed down during construction tend to be the worst.
Warning signs
What are the signs of a compacted lawn?
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Water puddles or runs off
Rain or sprinkler water sits on the surface or runs down the driveway instead of soaking in.
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The ground is hard to push into
A long screwdriver should slide several inches into moist soil without much force. If you have to lean on it, the soil is likely compacted. Test after a rain, not in a dry spell.
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Thin grass where people walk
Worn paths, play areas and the strip beside the driveway thin out first because they take the most traffic.
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The lawn browns early in summer
Shallow roots dry out fast, so compacted areas tend to show heat stress before the rest of the lawn.
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Weeds win in the same spots
Thin, hard ground is easier for weeds to take over than a thick lawn.
The fix
How do you fix compacted soil?
Core aeration, done in the fall and paired with overseeding. A core aerator pulls thousands of plugs roughly half an inch wide and a couple of inches deep, which relieves compaction and leaves openings for seed, air and water.
Spike aeration and liquid treatments don't remove any soil, so they don't relieve compaction the same way. Because compaction comes back with use, most fescue lawns here benefit from core aeration every fall.
Standalone aeration and seed starts at $279 and runs August through October. Here is when to schedule it.
Related questions
What people also ask
Why core aeration instead of spike or liquid aeration?
Core aeration pulls actual plugs of soil out of the lawn, which relieves the compaction common in Northern Virginia's clay soils and creates ideal pockets for seed. Spike aeration and liquid treatments don't remove any soil, so they don't relieve compaction or prepare a seedbed the same way.
How often should a lawn be aerated?
Most tall fescue lawns on Northern Virginia's clay benefit from aeration and overseeding every fall.
What do I do with the soil plugs after aeration?
Nothing. The plugs left on top of the lawn break down on their own.
Keep reading
More from the Learning Center
- How do you get rid of lawn weeds and keep them out? Pre-emergent versus post-emergent, why crabgrass timing follows soil temperature, and why a thick lawn is the best weed control there is. Lawn problems · 6 min read
- Why does a tall fescue lawn turn brown in summer? Heat, short mowing, brown patch and compacted clay are the usual causes. How to tell them apart, and what actually fixes each one. Lawn problems · 6 min read
- Why don't we offer biweekly mowing? Every-other-week mowing sounds cheaper. Here is what it does to a fescue lawn, and why we only mow weekly. Lawn problems · 5 min read
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