A regular lawn aeration program is essential for good turf health. In fact, if you ask any turf care professional what are the most important ingredients for healthy turf, all of them will mention aeration.
Turf that receives inadequate aeration is often dominated by shallow rooted grasses and broad-leaved weeds. Other common turf disorders such as disease, moss, poor drought resistance and water-logging are common place where aeration has been neglected.
What is aeration
Lawn aeration is the process of punching holes through the turf into the soil profile or root-zone below. This is done to increase the airspace within the soil. Over a period of time the air is squeezed out of the soil. This is caused by traffic, which can include people, machinery and vehicles.
Eventually the soil becomes compacted and growth begins to suffer as air, water and nutrient movement through the soil is restricted. When this happens then remedial action is required in the form of aeration.
Although all soil types suffer from compaction, clay soils are more prone to it than sand based soils. This is because the particles in a clay soil are a lot smaller, which means the air is easily displaced under constant traffic, especially during prolonged wet periods.
Benefits of aerating
- Improves the surface drainage: When a soil becomes compacted and air space is squeezed out, then drainage is impeded. This eventually leads to a saturated or water logged lawn during periods of frequent rainfall. Aeration helps move the water from the surface and into the soil profile, creating a drier lawn surface.
- Aids the breakdown of thatch: The bacteria (micro organisms) that degrade thatch require air in order to survive, if the soil becomes anaerobic, due to a lack of oxygen then the micro organisms will die out. Therefore aeration plays a major role as it encourages bacteria, thus keeping the thatch layer in check.
- Removes thatch from the lawn: Not only does lawn aeration help degrade thatch by encouraging a healthy population of micro organisms, it can also be used to physically remove thatch. Hollow tining or core aeration as it is sometimes called removes small plugs of thatch from the lawn.
- Improved rooting and the increase of desirable grasses: When a lawn is suffering from compaction, the grass roots have difficulty penetrating into the soil profile, due to reduced air space. Shallow rooted weed grasses, such as annual meadow grass begin to dominate the lawn, at the expense of the more desirable bent and fescue grasses.
- Helps integrate top dressing into the root-zone: A lawn top dressing is a thin layer of fine sandy soil that is spread over and worked into the surface of the lawn. Aeration, especially hollow tining or coring helps integrate the top dressing into the soil profile. This has several benefits to the overall health of the turf as it improves the soil structure.
- Helps increases the temperature of the soil: As lawn aeration creates a drier soil by aiding drainage, then this will help create a warmer soil as a dry soil retains more heat than a wet soil. A warmer soil will produce stronger growth than a colder soil. This is particularly beneficial in spring as it encourages early season grass growth.
- Relieve soil compaction: When a soil becomes hard and compacted, with little or no air space, then grass growth is often weak and sparse. The lawn becomes susceptible to a range of weeds, pests and diseases. Remedial action in the form of aeration will help relieve compaction, restoring the turf to its former glory.
When to aerate
Generally speaking, lawns can be aerated at any time of the year when ground and soil conditions allow. However to get the most from lawn aeration there should be some warmth in the ground. Therefore, in a typical year, early spring to late autumn are the best times to aerate the lawn.
During early spring a deep spiking would be beneficial to the lawn. However if the lawn has a deep layer of thatch then spiking should be substituted for hollow tining, as it removes thatch from the lawn. As hollow tining can be a little disruptive, wait for temperatures to rise and consistent grass growth, to speed up recovery.
During the summer period a shallow spiker such as a sarrel roller (a roller with small fixed spikes) is ideal to keep the surface of the lawn open. This lets in air and also helps any rain or irrigation penetrate into the soil and down to the roots of the plant. This can be carried out monthly during the growing season, if soil conditions allow.
Early autumn is the ideal time for hollow tining the lawn. This can be used in conjunction with scarifying, over seeding and top dressing. Autumn is a great time to renovate the lawn, as the ground is still very warm from the constant summer warmth. This ensures your lawn will get the maximum benefit from these tasks. Avoid hollow tining once the temperature drops and growth slows, as it can be quite disruptive and requires warmth to make a full recovery.
Once growth starts to slow at the end of the season slit tining or spiking can be beneficial, before growth finally tails off and winter sets in. Slitting is great for pruning the grass roots, aiding root development.
Types of aeration
When we talk about the different types of aeration we are referring to the various tines used to aerate. The three main types of tine are solid, slit and hollow tine.
- Solid tines: Also called pencil tines, these tines are used for spiking the lawn. Although they can be used at any time of the year, they are particularly beneficial during the growing season.
- Slit tines: These tines are a knife like blade, that penetrate into the soil and prune the roots. They are commonly used during the autumn and winter months. Deep slitting should be avoided during the summer as it can cause the surface of the lawn to crack open up during dry periods.
- Hollow tines: Also known as coring tines, remove a small pug of thatch/soil from the lawn. The ideal time to use these tines is early autumn as hollow tining compliments the other operations in the renovation program.