The best time to aerate St. Augustine grass is in early summer, when the grass is growing rapidly. On very compacted soils, aerating twice a year would not be out of the question. Apply fertilizer and water after aerating so the turf recovers rapidly.
Aeration is the process of mechanically poking thousands of holes in the soil. This allows water, oxygen and nutrients to better penetrate to the roots of your grass. Motorized aerator machines can be rented from hardware or tool rental stores.
●The best aerator is one having hollow tines (spoons) which pull up plugs of earth as the machine travels along.
●Solid-tine spike aerators pulled by lawn tractors are of little benefit.
●Use a criss-cross pattern. First direct the machine over the entire lawn, going back and forth in one direction. Second, direct the machine back and forth at right angles to the first series of trips.
●Examine a square foot area of the lawn. It, and every other square foot, should have at least 12 holes in it. If not, crank up the machine again!
●If the plugs of soil on the surface are objectionable, let them dry a few days, then drag a 5′ by 5′ piece of carpet across the lawn to pulverize them.
Anyone who has wielded a shovel in Atlanta knows that the soil usually contains a lot of clay. The tiny clay particles are easily packed tightly together by rain and foot traffic. After a hot Southern summer, the earth can seem like it is made of bricks!
The soil under a lawn becomes harder and harder as the years pass. It is rained on, walked on, played on and mowed regularly. Digging up the whole lawn to soften the soil is usually out of the question. What can be done to loosen the earth in a lawn while avoiding extreme damage to the lawn grass?
The answer is to “aerate” the lawn – using a rented machine (an aerator) which pokes holes in the ground and loosens it. The holes allow oxygen and water to penetrate more deeply. This causes roots to go deeper, making the lawn more resistant to drought and disease.
WHEN TO AERATE The best time to aerate a lawn is just before the grass begins to grow rapidly. Fescue grass makes most of its productive growth in fall, so September and October are prime months to aerate fescue lawns. Bermuda, zoysiagrass and centipedegrass lawns are best to aerate in late April – just as they have completed green-up, ready for vigorous growth.
WHICH AERATOR? Dr. Robert Carrow, University of Georgia turf expert, compared the effect of aerating with a “core” aerator versus a “spike” aerator. The hollow tines (sometimes called “spoons”) of a core aerator plunge into the ground and pull up a large plug of earth. Spike aerators insert narrow, solid rods into the earth. He found that the core aerator increased deep rooting and water extraction by 25 percent. The spike aerator showed no effects on grass health.
THATCH REMOVAL In addition to the deeper roots, the plugs of soil that are deposited on top of the ground help decompose thatch – without the risk of turf damage that power dethatchers pose. If you are doing a light fall overseeding on a fescue lawn, the holes left by the aerator make a perfect place for the seeds to fall into and germinate. Fertilizer also penetrates more deeply and helps a lawn recover and look its best after aerating!
Q: I used a hollow-tine aerator on my lawn. Do I have to collect the little plugs of soil that the aerator left behind?
A: Thank goodness you don’t have to collect them! You do have two choices, though. You can either let them gradually disappear or you can drag a section of carpet or chainlink fence over them to break them up. Wait three or four days after the aeration, allowing them to dry, before you drag and crumble the plugs.
Q: My neighbor has a spike aerator that he pulls behind his yard tractor. Will this aerate as well as a hollow-tine aerator that I have to pay to rent?
A: Not at all! In fact, the spike aerator may do more harm than good. It all has to do with the physics of pushing something into the earth. A solid object, like an aerator spike, tends to compact the soil below and on either side of the hole it makes. It also glazes the side of the hole as it withdraws, making penetration of air and nutrients more difficult. Remember, the process is called “aeration”, after all. Anything that impedes oxygen getting to grass roots doesn’t help them. The hollow tines that plunge into the ground and withdraw a plug of soil do not compact the soil and they do allow oxygen movement. Hollow-tine aerators are the best.
Q: If I aerate my lawn after I apply a crabgrass preventer, will that cause the preventer to fail?
A: New research says there will be no effect from aerating. In a research project at Michigan State University, Dr. Paul Rieke found that core aeration opens up such a small percentage of the turf that weed seedlings are still killed by the pre-emergent chemical. Don’t forget that the best time to aerate is when the grass is growing vigorously and when the earth is soft and slightly moist.