CO-Horts Blog

Friday, April 24, 2015

Aeration Done Right

Posted by: Alison O'Connor, horticulture agent in Larimer County

I'm first to admit that when I give advice it's a "do as I say, not as I do" recommendation. When it comes to lawn aeration (AKA core cultivation), Extension recommends that you aerate at least once a year, twice if you can afford it. The last time I aerated was...well...a few years ago. I did it myself (with the help of burly men to help lift the machine) and it was, quite frankly, an effort!
Aeration is the best!
Last week I was driving by a park in Windsor and saw someone aerating the turf. I was impressed by how great of a job he was doing, so I stopped to chat. It turns out that Mike McFadden, of Barefoot Farms in Windsor, is passionate about doing aeration correctly. After talking for a few minutes, I hired him to aerate my under-aerated turf the following day.

What Mike probably didn't realize is that I'd be photographing him. So thanks to Mike for his willingness to be the subject of this blog.
Mike McFadden of Barefoot Farms
Why should you aerate? For many reasons, including better water infiltration to the turf root system, to combat thatch build-up, to allow for better oxygen exchange for roots and to add organic matter to your lawn and soil. And it helps alleviate soil compaction.

Steps to aerating correctly:

1. Water your lawn a couple days prior to the aeration event. In order to pull deep plugs, the lawn should have good moisture. If the lawn is too dry, the plugs pulled will be very short or the machine will simply bounce around the surface.

2. Before you start aeration, mark your sprinkler heads. I used somewhat unorthodox markers, simply because I didn't have flags. But it's very easy to hit a sprinkler head with the machine. The aeration machine generally has one speed--fast--and they aren't very easy to maneuver.
The tree stump and mini American flag mark sprinkler heads.
The design of my irrigation system is another story...
3. The goal of aeration is to "Swiss cheese" the lawn--make as many aeration holes as possible. Up, down, back and forth, horizontally, vertically, diagonally. Try to get the holes on 2" centers. If the plugs are 2-3" deep, this is also excellent. This is where commercial aeration may fall short if they only make one pass. One pass tends to result in very few holes several inches apart and quite frankly, does nothing to improve the health of your turf, except that it makes you feel good that you aerated. Following aeration, your lawn should look beat up and ugly. This will pass in time. In the long run, aeration is incredibly beneficial. (As a note, Mike made four passes on my lawn.)
A lovely little plug. Not too much thatch and 2-3" long.
4.  If you rent equipment, you have the luxury of being able to control how many passes you make. Honestly, you can't make too many holes. Ok, well if your lawn is mud following aeration, maybe you made a few too many. But really--the more holes the better!
Lots and lots and lots and lots of holes is key.
5. Leave the cores on the lawn once you're finished. If you can't stand the sight of them, then rake them up and put them in your compost pile--don't throw them away. They are full of wonderful organic matter. If you leave the cores, they will break down with a few mowings.

6. Need to seed or fertilize? It's the P-E-R-F-E-C-T time following aeration. The holes you just created are ideal "germination chambers" for seed. Seed that drops into the holes will stay moist, have good contact with soil and be protected during germination. Fertilizer will also reach turf roots better following aeration (be sure to water it in). On a side note, if you applied crabgrass preventer to your lawn this spring, wait until August to seed--the crabgrass preventer will kill seedling grass.

It took Mike about 35 minutes to aerate my 3,000 square foot lawn. And I was thrilled with the result. He did mention that I have a much heavier thatch layer in my front yard (oops) and that doing it again in fall would be wise. So if it's been a few years, do your lawn a favor and aerate! It does the lawn good.
The chickens loved the freshly disturbed earth and had a heyday with worm bits. 


  1. Kate who loves her lawn in MadisonApril 25, 2015 at 10:21 AM

    We (well my burly wrestler son and his buddy) are picking up a coring machine today. He's not going to like mom telling him to go over the yard 4 times. Guess I'm ordering a couple of pizzas to bribe him and his friend. I'll fertilize too, since you say it's a good time to do it. I never knew. Thanks for the super info! Son is probably not so grateful! I love your blog and will show it to my neighbors, who never listen to me when it comes to lawns. What could a woman know about lawns anyway, right?

  2. I also love my lawn! Hope your aeration party was a success. I'm sure your son didn't mind the extra passes...especially when pizza was waiting!

  3. Aeration can be very difficult to do, even if you already have the right machinery for it. It’s great that you were able to meet Mike, and that he was able to help you out with your lawn. Anyway, these steps you’ve posted are very useful for those who want to try it themselves. Thanks for sharing this with us. Have a great day!

    Kristina Cobb @ Denny's Lawn & Garden