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Fall Lawn Decisions: To Seed or Not to Seed (Cool Season Lawns)

by Allyn Hane 07 Aug 2018

This guide for fall seeding is pretty long. If you want a PDF copy sent to you via email, click here and enter your email address

To Seed or Not to Seed, That is The Question

Hey there Lawn Care Nuts! Did you catch my video from the weekend? If not, some big announcements in there and some DIY Perimeter Pest Control action - spraying and praying on Sunday… loads of fun - go watch it here.

Today’s subject though, is much more important. It’s about seeding. Many of you will remember my guy Chris Heider who runs Handy Dad TV. He has been getting some great results following my cool season lawn plan this season. As you will see below, his results have been stellar - which has him wondering about fall time seeding vs applying pre-emergents. You can’t do both so a decision has to be made. With that, let’s get right into it:


Chris writes:

Al - Do you have a video that speaks to the "Big Fall decision" - whether to overseed, or apply a pre-emergent for poa annua and other winter weeds?

Your Cool Season Program mentions the decision needs to be made, but it doesn't discuss the decision process and tradeoffs.

I've seen other videos that say Poa Annua seeds can lay dormant for years, so I will potentially need a Fall pre-emergent for several seasons. My lawn looks good - best it's ever been - so I could probably skip seeding for a while. But...

You mention the use of the Jonathan Green fert plus crabgrass preventer (Tupersan) in Fall Step 3 (November). But the label only talks about using it in Spring.

Is there any reason I couldn't overseed in late August and apply the JG Tupersan fert at the same time to suppress the Poa germination?

I have a bag of Dimension too. Would it make sense to throw that down a couple months later - after the grass seed is sprouted?


So I asked Chris to send me some pictures of his lawn and where it stands today as a first example. You’ll see those scattered amongst the text below. But first, let’s look at the scenarios.

Should I seed in fall or should I not? And similar, aeration - should I aerate or not?

First off, if your lawn is sufficiently thick and healthy; don’t seed it. There is no need to seed just because all the other cool kids are doing it. I actually think that anytime you seed you run the risk of introducing foreign invaders into your lawn.

I’ve seen too many lawns that never had issues with poa trivialis suddenly show up with it one year. I’m not here to fight with seed suppliers - I will recommend a couple here in a minute who I KNOW have clean seed -- but I am just saying, whenever you put something that can grow in your lawn you run a risk.  

If your lawn is at least 75% turfgrass, then I’d say skip any fall seeding and work on the existing stuff. Save the expense and the risk.

From what I see in Chris’s pictures, he has strong, healthy turf that has come out of summer looking good. I’d rather then focus fall applications on helping push roots.

Cool season grass types strengthen roots in fall in prep for winter. Let’s help them. Hose that lawn every 3-4 weeks with a Greene County cocktail of:

  • 3oz RGS
  • 3oz Air8
  • 3oz Humic12

Combined 9oz/gallon, 1 gallon covers 1,000 sq ft

GET IT HERE - this is truly a great way to get your soil healthy and optimized just before winter but more importantly, it’s prep for Halloween Lawn Domination 2018!

Drive that into those roots while hitting it with steady doses of Milorganite or Ringer Lawn Restore. Feel free to mix up your fert if you want, and have a little fun. Be sure to get some more potash in there somewhere (3rd number in the analysis), potash is good for root development.

It’s time to flex with your fert my guy. Find a bargain closeout at Walmart or your local garden center. See what’s available at your local landscape supplier or Site One. You’ve made it all season so far and have done an incredible job - now it’s time to steer this boat all on your own and enjoy the Fert Life!

Tupersan - Pre-Emergent but NOT for Poa

Next, let me clear up the use of Jonathan Greene Starter Fert with Tupersan pre-emergent. That is mentioned on page 26 (I realize most of you won’t understand this part if you don’t have the book but read it anyway if you want good info). That’s a great product.  It allows you to throw down grass seed when you apply it and the pre-emergent Tupersan won’t affect the seed!

Awesome right?  

Not in this case. The issue with it is that you, Chris... you have poa-annua issues and Tupersan (the active ingredient in that product) is not labeled for control of that problem.

It’s good on crabgrass and foxtail and that’s why I mention it for a later fall application as a hedge against any strange early weather occurrences the next spring. But in all actuality, I should just take that part out of the book as it is a bit confusing.

This is also why the manufacturer themselves tell us it’s a spring product. So for everyone reading - Tupersan is a good pre-emergent that you CAN use with seeding but it only prevents:

  • Crabgrass
  • Barnyardgrass
  • Foxtail

Those are not really concerns in the fall time… but they are in spring and summer.

Preventing Poa-Annua/Trivialis

Now, since you are not going to seed, this is where you can put in work on preventing poa-trivialis or poa-annua next season. You have a couple choices here, those being Prodiamine or dithiopyr.

Prodiamine has a yearly maximum usage that is lower than dithiopyr but both are going to do the trick, so get the one that is cheapest for you.

Chris has dithiopyr already on hand so he is good to go…  ...but if you didn’t have that already... now is a good time to buy, DoMyOwn has pre-emergents on sale use code “FALL18”.

Make sure to water it in, ½” of water right after application.

When to Apply Fall Pre-Emergent (remember soil temps?)

Timing with pre-emergents is everything. I know you remember me hammering this home in spring when we were talking about crabgrass. If you remember back then, we were looking to get our pre-emergent herbicide down before soil temps hit 55 degrees.

We used tools like this one to know where our soil temps were sitting every day!  Crabgrass is a “spring annual” grassy weed and we watched soil temps rising as winter left and spring came in.

Now with, Poa Annua and Poa Trivialis (just call them “annual bluegrass”), they are winter annuals, meaning, they germinate in fall time, wait over winter, grow stronger in spring, show themselves in summer, go to seed and die when air temps near 85-90F.

Then the cycle starts over when soil temps get cooler and dip below 70 degrees F. The good news is, it’s only early August right now, so you are at a good time to get stocked up!

Guess what else? ... We have soil temp markers for poa-annua that we can follow online … remember, our target here is soil temps at 70F -- the poa will germinate when we hit that mark for several days (seed depth matters, and available moisture too)… so for your PRE-emergent herbicide to work, it’s got to get down and watered in prior.

Right now, soil temps in Jersey where Chris lives are still in the 80s so he’s all good and still too early. But don’t you get complacent my dudes!! (and dudettes, thanks Denise B) because it only takes a few overcast (no sun) gray cold days and you’re there.

Also, keep in mind, you only have to cover yourself for 90 days or so. If you get this down in early September, for example, you should be good. If you live further south, and your winter is later, you may consider a double application here too - hitting the lawn in September, and again in later November.

This is why dithiopyr is effective because it has a higher “yearly maximum” giving more flexibility. Throw’er Down!  (check your own soil temps here)

Quick: just because my guy Chris is good in Jersey, don’t you sit back northerners! Look at my friends in Bozeman, MT. Ya’ll better get to spraying and praying for your poa here pretty darn quick!

In summary - let me make clear - if you are throwing down grass seed in the fall, you CANNOT use a pre-emergent. You have to make the choice - do I need to seed or can I make a go at thickening my existing grass and also protect against poa next year?

But What About Aeration and Seeding?

My friends - I love to aerate. Truth be told, when I was working for TruGreen and feeling a bit fat, (like always), I’d take an aeration route for the day and kick my own ass. Ain’t no Cross Fit that can match a $4,000 day out aerating in Mokena, IL.

Character building aside, if you are seeding, aerating the lawn makes a nice seed bed. Double or triple pass the lawn with the aerator and pull as many cores as you can. If you watch the Discovery show, Gold Rush, you’ll know that Tony Beets says “Drill holes, Drill holes” to Parker when prospecting… that’s all he says… it’s the key!  

I’ve always said the same thing about aeration and seeding - poke holes, poke holes, poke holes!

How to Succeed with Grass Seed

Reason being is that when you seed… the success depends on 3 factors;

  • Heat - gotta have warm soil and air temps to germinate the stuff, and they have to sustain long enough for the new grass to “harden off” for winter.
  • Water - water-water-water - keep the seed constantly moist. Like your first real girlfriend. Always wet.
  • Seed-To-Soil contact. This is how aeration can help. Poking those holes helps, and you should poke as many as you can. Yes, seed falls into, and gets washed into (from your irrigation) the holes… the more you create, the more better… but in general, just getting everything all stirred up helps too.

So in my experience, aeration is still very important IF you are going to overseed. That’s how I have been taught, and that is what my experience has proven to be true. If you are going to seed, aerate first.


That last one there - the poking of the holes to create that seed-to-soil contact -- that is a bit of a myth so it seems, at least according to the George Clooney of lawn care, John Perry. He is the man who created the Greene County Next products that I have been using this year. I’m a strong believer from the results I have seen. However, he is now saying that Air8 can be used not only to create a great top-soil (over time) but can also be used straight up with overseeding and NO MECHANICAL AERATION is needed!

John and I are friends. Everything he has told me about his stuff has been true. And iron sharpens iron, so… we are going to test it this fall. Here is my buddy Jake The Lawn Kid showing you the lawn we will test it on. Gonna be fun right?


Where to Buy Grass Seed

I’ve used the stuff you can get at Home Depot and it’s worked fine. Scott’s seed and Pennington seed are what I have seen and used the most often. Get the stuff that has the green coating on it. This will help retain moisture against the seed and improve germination.

However, if you want some really good, clean seed that I KNOW is top quality, there are two sources for you.

  1. Seed Super Store. I know Drew the owner and he cares about his product and only carries the best of the best. He also cares about homeowners. I don’t make any money from Drew and he is not a sponsor. I trust him and that is why I recommend him to you. Call him and tell him what you are looking for, your site situation, your sun/shade ratio, etc. You will not be disappointed. Check out his KBG selection here.
  2. If you want larger quantities of Turf Type Tall fescue (50 LB sacks) then Pete from GCI Turf Academy has come out with his own blend and based on how awesome his own lawn looks, this has to be quality stuff. Plus, Pete is a lawn care pro -- he knows how picky homeowners can be about grass seed so if a guy like Pete is going to put his name on something like that - I know it has to be high quality.


As always, I get way too wordy in these emails. But I think you guys who make it this far down the page appreciate the details. Either way, here’s a summary:

  1. If you have a poa-annua issue, lay down pre-emergent herbicide before soil temps hit 70 degrees on the decline in fall. Use Prodiamine (here is a liquid option) or dithiopyr. Water it in immediately.
  2. If your lawn is sufficiently thick, don’t seed and don’t aerate. Spend your time and money building thicker roots with organic fert. Push in some potash (Air8) and bio-stimulants.
  3. There is no need to mechanically aerate your lawn anymore unless you are seeding. If you are seeding, then mechanical aeration helps make a nice seedbed. If you don’t need to seed but want to help your compacted soil - use this.
  4. If you need good grass seed - Call Seed Super Store or Pete at GCI

Thanks for reading all the way to the end here. I hope this has been helpful, I’ll see YOU in the lawn!

This guide for fall seeding is pretty long. If you want a PDF copy sent to you via email, click here and enter your email address


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