Aeration is the process of rearranging of your lawn’s soil by breaking up its surface layer. The result is "pores" in your soil that can help address absorption and drainage issues caused by heavily trafficked and compacted soils.
Aeration is essential for heavily trafficked areas with soil prone to compaction (clay and silt). Compacted soil impacts the ability for oxygen, water, and nutrients to penetrate past the topsoil to reach the root zone, where crucial lawn nutrients can stimulate root growth to create healthier, stronger grass. Some benefits of aeration for compacted soils include:
If you have a clay loam or clay heavy soil, you should evaluate the need to aerate each season. If you have softer soils, it’s a good idea to check, but if your soil and grass are healthy, you likely don’t need to aerate.
A great way to test if your lawn needs aeration is with a screwdriver. Yep, a screwdriver! Flathead or Phillips, it doesn’t matter – take the screwdriver and insert the head into the soil. If the screwdriver can’t be inserted very easily when the soil is moist, then your lawn likely needs a little TLC (aerating and fertilizing).
If you’re not core aerating, then you’re probably not helping your lawn. Core aeration is when those little tube plugs are removed from the lawn. Some aeration practices just force a hole in the lawn without any removal; this jamming makes soil compaction worse.
For compacted soils, raking up the plugs will go a long way. Otherwise, these plugs will break down back into the soil. If your soil is not compacted, plug removal is not necessary.
There’s no need to own the mack daddy of lawn aeration equipment outright (and let it collect dust in the garage with your high school trophies) because you won’t aerate your lawn all that frequently. Rent the equipment from a local hardware store, or hire a local landscaper.
To maximize benefits of core aeration, you want it to be synchronized with peak growth of your lawn. For cool-season grasses, you’ll want temperatures to be between 60 – 75 degrees for several weeks after the aerating. (80 – 95 degrees for warm-season grasses.) These temperature ranges are more so guidelines as opposed to strict rules; your lawn will be fine if the weather gets outside of this 15-degree window.
This creates a choice for cool-season grasses: is it better to aerate in the spring or fall? It really depends on your own goals and challenges with your lawn. Aerating in the spring will have a better benefit over the whole growing season, but can also be inviting to spring weeds like dandelions. Aerating in the fall has fewer weed risks, but then you’re getting close to the end of the growing season. It really depends on you and your lawn.
Some yards don’t need aeration or don’t need it very often and can be aerated once every two or three years. High-traffic areas with compact prone soils can benefit from yearly care. If you’re aerating in the fall, be sure to faithfully remove as much lawn thatch as possible by raking deep rather than just skimming the autumn leaves off the top of the lawn.
BOTTOM LINE: Knowing if and when to aerate your lawn really depends on the health of the grass and your lawn’s soil.