When Should The Last Mow Of The Season Be?

It's mid-September, and the fall season has arrived. You can't wait to put away the lawnmower. Lawn care providers are looking forward to winter vacation. I'm getting ready for customers to call me the last week in September and ask me not to bill them for October.

Is it time to stop mowing?

Located here in Euclid, Ohio, I will honestly say that you or your lawn mowing service provider to keep mowing in September, October, and November. You may even be mowing into December! 

Why?

Historically the grass is still growing at this point. In September, there is usually a brief moment when the growth mimics spring. Then poof. Super slowdown. This sets the mindset to stop mowing. But you should not yet stop.

Before I tell you when it is okay to officially stop mowing, you need to understand the importance of mowing well into the fall.

Why is it Important to keep mowing in the fall?

#1 The grass is still growing

In Northeast Ohio, the average October high temperatures are around 68 degrees at the beginning of October and drop to highs averaging 57 degrees by the end of October. In November the average high temperatures stay above 50 degrees until November 15th. 

Grassroots will still grow with soil temperatures below 50°F.   It is not until soil temperatures drop towards freezing (32°F), that grassroot growth will slow down tremendously.

This would put air temperatures around 42 degrees before the grass slows down. Historically, this does not happen until December 11th.

This leads us to point #2.

#2 Grass length going into winter is critical

Your last mowing for cool season grass should be at 3 inches going into winter.  If you stop mowing too early in the fall, there is a risk your grass will be taller than this height.

A slightly taller height may not do much harm, but if you stop mowing at the end of September, and the grass grows slowly into late November or early December, this could lead to 4 inches of grass.

Worst yet, you probably wouldn't notice until the grass begins to have snow mold. This is a result of having longer blades of grass that bend over each other.

Snow mold could spread throughout the lawn, make dogs feel unwell, trigger allergies, and is completely unavoidable. All that you need to do is keep mowing even though fall has arrived.

So, when is it okay for you to stop mowing the lawn?

We mentioned earlier that the grass will stop growing tremendously when air temperature highs are consistently below 42 degrees. Most articles on the web will tell you to stop mowing at first frost. But in the Cleveland area, this would be around November 7th. After that, you may get 3-4 weeks of temperatures between 50-60 degrees.

While you should never mow the grass when temperatures are below 40 degrees, and you definitely should not mow with frost on the lawn, it still may not be time to safely stop mowing.

I'm not kidding. Our weather is wildly unpredictable around here.

What to watch for in determining when to stop mowing

But based on my experience, and watching our weather each fall, I recommend you stop mowing once temperatures are regularly below 50 degrees. Using a 7-day forecast, I would take the average of those 7 days. If the average is below 50 degrees, stop mowing.  Maybe.

To be sure the grass is not too much above 3 inches, I would mow the lawn one more time once I see the 7-day average temperatures are below 50 degrees, so as long as there is no frost on the grass, and the temperatures are above 42 degrees.

Most likely, this would not happen until mid or late-November or early-December in some years. That means mowing in October is necessary, and you should not stop mowing the grass that early into fall.

But as we mentioned at the beginning of this post, after 6 months of mowing regularly, you want nothing more than to store the mower away come October. Mowing fatigue has set in.

How can you endure these last few weeks of the mowing season?

4 tips on mowing the lawn in the fall.

Mowing in the fall is quite different than mowing in the spring or even summer. At first, the temperatures fell pretty well. Later in the fall, it does get nippy, but because the grass is not too tall, it is usually quicker to finish. Here are a few tips while mowing into October and November.

#1 Adjust your frequency

One of the best tips for lawnmowing is to make sure you are mowing at the right frequency. No doubt, the September growth spurts had you mowing weekly, or every 5 days. In October, it is okay to begin mowing bi-weekly. 

#2 Adjust your mowing height

Because you want your grass no longer than 3 inches going into winter, you need to lower the mowing height in October. If you were following the proper mowing heights for cool-season lawns in our area, you should be at 4 inches.

Lower it to 3.5 inches during the first mowing in October. Around mid-October lower it again to 3 inches. Keep it at this height until the last mowing.

#3 Prepare to mulch leaves

If you deal with leaves on your lawn in the fall, do your lawn a favor and mulch the leaves into the lawn if you can. This should be doable so as long as they are not too thick.

Once they get too thick I would consider the side discharge. If not you will need other means to handle the leaves, like bagging, raking, or blowing them to the curb for city pickup. 

I believe the only time to bag the grass from the lawn is the first mow of the spring.  In the fall, raising the mower height and bagging the leaves with the mower when they get too thick to mulch back into the grass is okay.

#4 Find your mowers' manual

Okay, after all the above has been accomplished, it is time to look for the mower manual. Read and get familiar with the section that talks about winter storage. You'll be done mowing soon.

In Summary

Congratulations! You wanted to stop at the end of September, but you kept the mowing going. You kept the lawn from unnecessary snow mold disease. You feed the lawn valuable nutrients by mulching the leaves back into the lawn.

You rocked. You kept looking at the 7-day forecast calculating and waiting for an average below 50 degrees during any 7-day rolling period.

And come spring, your lawn will thank you for not stopping mowing until the proper time has arrived.