When is the best time to aerate a lawn

You are currently viewing When is the best time to aerate a lawn

What is aeration?

Aeration is the process of creating small holes in a lawn’s surface.  Aeration is achieved by three methods:

  • Spike aerators pierce the lawn surface and penetrate down to the bottom of the grass roots.  Spike aeration can be carried out with a garden fork or special garden sandals.
  • Slicing aerators are powered devices that slice through the top layer of a lawn surface.
  • Core aerators pierce the soil surface and remove small cores or plugs from the lawn.

Why is aeration important?

Aerating has the following benefits for a lawn:

  1. Increases drainage to allow roots to absorb water better but also to reduce the amount of surface water that can lead to a build-up of moss and fungi.
  2. Allows air to reach the grass roots.
  3. Reduces soil compaction which allows roots to absorb a greater amount of nutrients.
  4. Stimulates root growth by creating space for smaller, more fibrous roots.

When should I aerate my lawn?

The best time to aerate your lawn is when the grass is actively growing.  This will allow time for the grass to fill back any holes made by the aeration process.

If you are using aerator shoes or a garden fork, aerate the lawn any time in spring and summer.  This process is very beneficial during the drier, summer months as it will allow the maximum amount of water to reach the grass roots.

If you are using a hollow tine aerator to “core” the soil, the best time of year to use this tool is during late summer to mid-autumn.  The grass will be generally damper which will allow the aerator to penetrate the soil sufficiently, but will also allow enough time for the lawn to recover before the grass goes dormant over winter.

Lawn aeration will be easier to perform for both you and your equipment if the soil in your lawn is slightly damp.  It’s much tougher to aerate dry lawns.

Is there a bad time to aerate your lawn?

The golden rule is never to aerate a dormant lawn.  If your grass isn’t growing, don’t aerate it.

Avoid aerating when your lawn is very wet as the lawn can become quite torn or smeared with mud.  This won’t damage your lawn but will make it look poor purely from a cosmetic point of view.

If you have a powered slitter, avoid using it during the drier, warmer months as the slits can open quite wide.  Again, this is purely a cosmetic issue and won’t cause any long term problems with the lawn.

If you are using a hollow tine aerator, avoid using this during early spring as it could cause too much water drainage if the weather turns particularly dry.  Wait until the grass is actively growing.

Another reason to avoid performing this form of aeration during the early spring is due to the increased risk of spreading weeds.  The plugs/cores created by the aerator might expose weed seeds to the top-soil layer at the time of year that weeds are actively growing.  Ideally wait until late summer or early autumn.  If you do need to perform core aerate the lawn in spring, pickup all of the cores immediately after aeration.  

How often should you aerate your lawn?

Coring the lawn with a hollow tine aerator should be carried out no more than once a year.  This form of aeration has the largest impact on your soil so the lawn will take longer to recover from it.  Coring the lawn too often will have a negative impact on its health.

Lightly spiking the lawn with a garden fork and aerator can be carried out weekly if the lawn isn’t too wet.

Should I pick up cores/plugs after aerating?

It is best to leave the plugs to dry on the lawn surface.  The will quickly and naturally break down by drying out and decomposing into the soil.  They will add the nutrients lost from core aeration back into the soil which will further promote strong grass growth.