Cool Season Lawns Across America: September 2018

What’s up ya’ll, how is your September “fall recovery” plan working out? Hopefully you have one! Or maybe you think it’s too late? Cool season lawns… let’s find out!

Cool Season Lawns

Hello there Cool Season Friends. That’s you folks with the Kentucky Bluegrass (KBG), Turf Type Tall Fescue (any fescue really) and Perennial Ryegrass. Most of you have blends of these - which is great!

So let’s talk through some options and look at the weather to help you decide just where to take action. First off, for a good majority of you across the US, it’s not too late to undertake the big one: the full Fall Aeration, Overseed, Starter Fert and Milo. Me and Jake have been working through it together - here is the full playlist with my vids and his all put together:

Now that playlist is our way of working through the very steps that I illustrate in my cool season hybrid organic lawn guide. If you’ve been waiting to pull the trigger, now is the time because you have FRESH vids to back up what’s written in the guide.

On top of that, I’ve already started updating it for 2019. I’ve gotten HUNDREDS of questions since we started selling this plan and that then allows me to update it with the most current info and detail, every single year.

So if you buy it now, fear not, when I update it in 2019, you’ll get the updated version free - this is advantage to ebooks! In fact, every time I update the book (yearly) you’ll get the fresh, updated copy. Buy it once, get lifetime updates. That’s domination!

But is it too late for seed? Let’s talk about that by looking at weather windows.


When seeding, we care about air temps and soil temps, but for ease of understanding, let’s just focus on the outside air temperatures today.

Ideally, when seeding, you want outside air temps to be under 80 degrees during the day, and over 50 at night. You really don’t want more than a few hours of time where the temps rise or dive into either extreme and that window needs to last 30-45 days or so. (grass type matters - more on that down below)

So just keep that timeframe in your mind: 30-45 days. That’s about how long it’s going to take most cool season grass types to grow in and gain enough strength to survive the coming winter.

First off, consider where you live and how fast the winter is actually coming!

Let’s look, for example, at Miamisburg, Ohio. A great little town in Southwest Ohio where I lived for a bit when I worked for TruGreen in nearby Springboro. If you ever visit, be sure to stop at the famous downtown Hamburger Wagon. Miamisburg, here is your 10-day forecast:

You guys are right in the perfect window to seed. Get your seed down now and it will be germinating in perfect temps a few days later. Start this coming Saturday, September 15, and your perennial ryegrass seed will be coming up sometime around the 22nd.

Make sure you water! Water! Water! ...for a good 20 days or so! Don’t Worry, Be Happy!

But hold on now… winter is certainly coming, and this is where you may have to take some risks. Remember, ideal temps for our grow should not dip much below 50 degrees until we’ve gotten in a good 2-3 mowings.

This gives the adolescent grass enough time to put down roots and store up energy. At this point, my math then takes us to somewhere around October 15. It looks like this:

As the month wears on, the threat of frost will loom, which is not good… but it’s the freeze and then dreaded, “hard freeze” that we need to be mindful of.

Freezing is pretty obviously bad right? Temperatures fall below 32 degrees F and growth can stop and even shut down. In our scenario here in Miamisburg, the average first freeze occurs Nov 1-5.

If we seed in Perennial Ryegrass Sept 15, it germinates Sept 22-26 and grows perfectly because you keep it watered… then you are golden. Your Perennial Rye will have enough roots to hold up over winter as long as you help it pack in nutrients just before it shuts down for good. (John Perry, aka. George Clooney, talks about lawns storing up for winter in this video here.)

Why Perennial Rye Though?

Yes, I have been favoring Perennial Ryegrass in this scenario haven’t I? That’s because of the window; it’s shrinking.

And one way to hedge your bets if you still want to get a seeding in is to choose a blend that is more heavy in Ryegrass than other cultivars. You could theoretically seed in something that is 100% ryegrass if you want. Nothing at all wrong with that!

Perennial Ryegrass typically germinates within 7 days or so, whereas Kentucky Bluegrass is going to take more than 3 weeks! Go back up and look at the screenshots and charts but run the Miamisburg math adding 14 days waiting on Kentucky Bluegrass.

See the weather window slamming shut there real quick there? So if you still want to seed, and you are in Miamisburg, choose a blend heavier in rye and fescue, then Throw’er Down, and hope for the best.

Of course, you can run this same scenario for your own area; just do a few google searches like I did and you’ll have your data in no time. Then record your findings in your lawn journal and get ready to rock!

One Last Thing - Super Cool

There’s a YouTuber named Ben, The Lawn Guardian, and he has organized a fundraiser that me and several others in the lawn care community are participating in.

The cause is one that I am 100% behind and I’ll be talking about it more later this week. In the meantime, please go subscribe to Ben’s channel so you can see the official launch video when it is published this Friday.

I love the fact that we are coming together as a community to do something good for others and I’ve got great respect for Ben who has put in work to organize it. I’m excited to share it with you.

I’ll see you in the lawn!


PS-  On SEED GERMINATION TIMES: yes, I know that you know someone who germinated bluegrass in 3 days and fescue in 12 hours or whatever else you have seen and heard online. I get it, those things can happen… but for the most part, the germination periods I give you here are general standards that apply time as a hedge. I never make strategies based on outlier results. I try to make strategies that allow for some fudge factor. Capish?

←  Back to News