UK gardening help and assistance

Lawn Aeration - Aerating the lawn

What is lawn aeration?

Lawn aeration is the process of creating air channels in your lawn so that air can freely pass into the soil and circulate around the grass roots. This aeration is achieved by either:

  1. removing small cylinder shaped cores about 0.5cm wide and 5-10cm deep (similar to the idea of coring an apple) , this is known as core aeration.
  2. creating aeration channels by inserting solid spikes (such as the tines of a garden fork) into the soil. This form of aeration can give rise to soil compaction and so

Why do we need to aerate the lawn?

Over time the soil that the lawn grows on can become compacted due to a number of reasons such as use for sports, walking, vehicles, parking and children playing. This soil compaction can have a negative effect on your lawn. The damage to your lawn from soil compaction results from the pore spaces within the soil becoming smaller and this leads to both a reduced amount of air held in the soil, restricted air flow and reduced water infiltration into the soil. These results of soil compaction are damaging to a lawns health.

Reduced air levels and restricted air circulation in the soil means that the grass roots are less able to take up oxygen. Reduced soil pore space also leads reduced levels of nutrient uptake from the soil. Oxygen is a vital input into a plants growth cycle. If the ability of water to infiltrate the soil is limited by soil compaction then the water will not infiltrate as deeply into the soil as normal, this means the lawns roots will not develop as deeply and so the lawn will be more at risk from drought and other environmental stresses. Soil compaction also means there is greater resistance against the roots as they try to develop to greater depths. Poor development of roots below the soil will result in a poor lawn condition above the soil.

There are other factors besides soil compaction that may give us reason to aerate our lawn. If our lawn contains a considerable build up of thatch then we can use core aeration to help break down the thatch. This process occurs as the cores of soi that are left on the lawn surface by core aeration introduce soil micro organisms into the thatch layer. These micro organisms breakdown the layer of thatch and return nutrients to the soil.

Lawn aeration may be necessary on heavy clay soils to help soil air circulation and water filtration.

How does lawn aeration benefit my lawn?

Lawn aeration has a number of benefits including:

  • The increased water, oxygen and nutrient uptake by the grass roots
  • Improved development of roots to greater soil depths
  • Enhancing water infiltration into the soil and to greater depths
  • Encouraging the breakdown and decomposition of thatch by soil microorganisms
  • Helps prevent the loss of valuable fertilisers due to run off from compacted areas

Does my lawn need aerating?

How can we tell if our lawn needs aerating? The simplest way to determine this is to remove a section of turf from the edge of the lawn to the depth of a spade. If the roots of the grass are only reaching and inch or two from the soil surface then your soil is potentially compacted and could benefit from aeration. If you know which grass type your lawn is then you should be able to determine the normal depth that the roots should develop to.

How do I aerate the lawn?

Lawn aeration can be carried out by hand or with the aid or a lawn aerator machine. Lawn aeration should be carried out once a year and should be carried out at the beginning of the lawns growing season, early spring in the UK. There will be less competition for light, water and soil resources from weeds at this point in the growing season.

When should I avoid aerating the lawn?

If you have sown a new lawn from seed then do not aerate it in its first year of growth. If you have a lawn that receives no significant compacting influences and you have aerated it recently then there may be no need to aerate it every year.

You should also avoid aerating the lawn after periods of heavy rainfall when the soil is wet through. This is because wet soil will stick in the ‘cores’ of the aerator and so the coring action of the aerator is greatly impeded.

A moist soil is suitable for using the aerator on so thoroughly water the lawn a few days before you intend to aerate it.