Early fall, between mid-August and late-September, is the best time to aerate your lawn in Minnesota. This timing allows your lawn to take advantage of the decompacted soil, and have a strong fall growth spurt. It also sets your grass up to easily survive winter dormancy and have an incredible spring green-up.
Avoid spring aeration because this invites invasive weeds. It also doesn’t take advantage of the strongest growth period of grasses planted in Minnesota, which is fall. If you want to serve your yard best, aerate in autumn.
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Why Aerate in Fall in Minnesota?
The cool-season grass varieties planted in Minnesota thrive in temperatures below summer peaks. Simply put, aerating in fall takes advantage of the strongest natural growth period for our northern grass varieties and magnifies its benefits.
You’ve probably noticed that after spring green-up, your lawn growth slows in peak summer months, then roars back to life in fall. This season represents the best opportunity for grass growth because temperatures are optimal for Minnesota grass species and there are fewer weeds sprouting and stealing nutrients from your lawn. The biggest benefits of fall aeration are:
- Decompacts soil prior to fall grass growth spurt.
- Does not invite weed seeds in soil to sprout.
- Encourages grass root growth, to store energy for winter dormancy.
- After aeration, you have the perfect conditions for fall grass seed overseeding.
Don’t wait too late to aerate, though. Aerating in late fall exposes roots to winter temperatures and halts growth, preventing your lawn from benefiting from the process. Also, never aerate dormant, brown grass. Aeration only gives benefit to actively growing lawns.
Can You Aerate Your Minnesota Lawn in Spring?
Aerating your Minnesota lawn in spring is not recommended. Many lawn care services in the region advise against it because it simply doesn’t set your lawn up for success. Some of the downsides of spring aeration are:
- Grass will experience a smaller boost in growth compared to fall.
- Weed seeds exposed by aeration will sprout.
- You may have to spread herbicides to stop invasive weeds, adding to lawn care costs.
Similar to spring, avoid summer aeration. Cool-season grasses grow slowly in summer, and the holes created by a good aeration machine may cause the soil to dry out during hot daytime hours. This can harm your grass or necessitate extra watering.
How to Tell if Your Lawn Needs to be Aerated
Testing to see if your Minnesota lawn needs aeration is a simple process. All it takes is a screwdriver and a few minutes of your time. Simply follow these steps:
- Water your lawn 1 day before testing soil.
- Push a screwdriver into the soil.
- If it is difficult to push the screwdriver into the soil 2–4 inches, the lawn requires aeration.
- If the screwdriver easily sinks 2–4 inches into the soil, the lawn does not need aeration.
- Test 3–5 areas of the yard, including high-traffic areas. Sometimes only portions of a yard become compacted.
What is the Best Aerator to Use on a Minnesota Lawn?
Rent a core aerator from your local hardware store. These machines do the best job because they remove cork-shaped cores of soil from the ground and drop them on the lawn surface. This promotes true soil decompaction, breaks up thatch, and allows nutrient and water penetration.
Spike aerators won’t do the job nearly as well. By driving a spike into the soil you are actually compacting all the soil around the spike. This a negative in the long run. If you want a healthy lawn, go with a core aerator.
Benefits of Lawn Aeration
Aeration has a host of benefits, from encouraging a fuller lawn to allowing nitrogen in fertilizer to enter the soil. If you’re on the fence about whether to aerate, consider these benefits:
- Brighter, healthier visible grass.
- Increased grass root growth.
- Increased water penetration down to the root layer.
- Decreased thatch buildup.
- Better nutrient absorption from fertilizer and natural sources.
- Creates ideal circumstances for spreading grass seed.
There’s a reason so many experts treat aeration as the holy grail of lawn care—it makes so many other tasks easier. If timed correctly, it provides a huge upside for your lawn.
How Often Should Minnesota Lawns Be Aerated?
There is no catch-all aeration schedule for Minnesota lawns. Whether you’re in Rochester, Minneapolis, or further north in Duluth, it all depends on how quickly your soil becomes compacted. There are many factors behind this, from soil composition to the amount of traffic your lawn gets. It may not seem like much, but human and pet traffic can go a long way to compacting the soil.
Lawns should be aerated as often as the soil fails the soil test described above. Although aeration may not be necessary on a yearly basis, check the soil once per year to see if your lawn is in need of aeration.
Best Time to Aerate Your Lawn in Minnesota
The best time for lawn aeration in Minnesota is early fall. Plan to aerate between the end of August and the end of September for best results.
This timing gives your lawn ample opportunity to take advantage of cool fall temperatures for impressive growth but doesn’t allow weeds to invade. Aerating in early fall also avoids the pitfalls of aeration in other seasons. Spring aeration invites weeds, summer aeration can dry out your soil, and aerating too close to winter will not benefit your grass. For a greener Minnesota lawn with less hassle, make sure to aerate in autumn.