Grass Seed Germination Temperature

Grass Seed Germination Temperature

Everybody wants a think, luscious, healthy lawn, however getting to that point isn’t always as easy as it seems. Not only does it take good equipment, but it takes perfect timing to plant your grass seed for optimal growth and health. In this article I’ll discuss the ideal grass seed germination temperature, so you don’t waste that expensive seed you purchased.

Here are some things to consider when deciding when to seed your grass.

Timing: When to Plant Grass Seed

Now, I know what you may be thinking, “Why does timing matter? Doesn’t grass grow the same all year long?”

The answer is no.

When seeding your grass, it is important to consider the planting season as well as the natural growth period of your seeds. Different types of grass grow better in different seasons.

While some grasses may seed and grow better during hotter weather, others may grow better during colder weather. It is important to know your seeds and know the type of grass you are growing so you can time your planting accordingly.

Best Temperature for Grass Seed Germination of Different Types of Grass

Taking advantage of your grass type and its natural growth patterns will help it to germinate more quickly, therefore giving you the best chance to live and be healthy. It will also decrease the likelihood that you will have dead patches in your lawn.

So now you know that timing is important, but you may be thinking, “So, when should I plant my grass?”

Grass Seed Germination Temperature (Cool Season Grasses)

Getting straight to the point, Fall is the best season to plant cool-season grasses. 

Cool Season Grasses Germinate Best Between 50 and 65 Degrees Fahrenheit.

The best way to determine your soil temperature is by using a soil thermometer. You can order one online, or you can buy a soil thermometer at any local home improvement store.

Keep in mind when thinking about when to plant your seeds that where you live has a big effect on when you plant.

For some climates, you may need to plant your cool-season grasses at the beginning of the fall season. In other climates, you may have to wait a little longer and plant them closer to winter.

If you live in a colder climate, a good rule of thumb would be to plant your cool-season grasses at least 45 days before the first frost. This will give you seed enough time to germinate and grow before the soil gets too wet.

When to Plant Warm Season Grasses for Best Germination

Keeping it short, the best season to plant warm-season grasses is Spring.

Warm Season Grasses Germinate Best Between the Temperature of 65 to 70 Degrees Fahrenheit.

It is best to plant in the Spring because of the balance between wet and dry. In the Spring, you have enough rain to create the moisture needed to germinate the seeds. You also, however, have the heat needed for your warm-season grass to thrive.

Do Your Research

Growing and taking care of your new grass is not hard if you have done your research. Before buying seed, make sure that you know what seed you’re buying and when it is best to plant it.

Now that you know the ideal grass seed germination temperature for your new seed, you will be ready to grow a healthy lawn!

Related: Help My Lawn is Nothing but Weeds!

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Sarah’s blog, Lawn Chick, is read by over 2 million homeowners each year and she is regularly cited as an expert source of lawn care knowledge by major publications. Her goal is to meet you where you are, and help you achieve a yard you’ll be proud of. Ready to take the next step toward improving your lawn? Grab her free lawn care cheat-sheet: What to Do When - Take the Guesswork Out of Lawn Care, or upgrade your garage by browsing her favorite DIY lawn care products.

8 thoughts on “Grass Seed Germination Temperature

  1. kim hill

    Hi, great site! I live in upstate NY with about an acre of yard. I missed the fall planting season : (. Weeds like creeping charlie, clover, crab grass, etc… are taking over. I dethatched last fall and I am dying to aerate and over seed this spring although I believe fall is better from what I’ve read. So do you think it’s a good idea to work on the weeds this spring and summer and seed in the fall? I will hate looking at the yard for that long but it seems to be the best plan?

    • Hi, Kim! Yes – I’d probably recommend that you wait until fall if you already have crabgrass germinating where you live and didn’t get a pre-emergent down this spring. If you haven’t seen crab-grass germinating don’t wait! Get a pre-emergent down this week to block it and you might still be able to overseed this spring. Here’s my guide on that topic. If you’re already seeing some annual weed pressure, you’re better off just making peace with it, mitigating damage from crabgrass and spraying your creeping charlie this season, and going gang-busters in the fall. Make sure you apply a good pre-emergent next spring and I’d overseed again in the spring as well. Your lawn should be nearly perfect next season if you follow my tips for a fall lawn reno and are on top of pre-emergent and a second round of overseeding next spring. Good luck!

  2. Andrea

    Hello, I just finished doing a lot of seeding and overseeding in our lawn. After reading your article I;m guessing I should have used a pre-emergent first. Will I still be able to do this, and if so, when should I do it? Live in Ontario, 1-2 hours hours west of Toronto if that helps. Thanks very much!

    • Hi, Andrea!

      Thanks for the comment. I recently overseeded as well and all my seedlings are starting to peak out of my New England soil now.

      You’re right – when you do plant new grass seed and begin watering frequently you are creating ideal conditions for crabgrass and other weeds along with your seedlings, which can be a problem. But many pre-emergents will block your grass seed from germinating, so you have to be careful about what you choose and use. You really have two options:

      1. Choose to just keep going as you planned, knowing there will be some weeds that germinate that you’ll have to treat with a selective herbicide (or hand-pull) in 4-5 weeks. There’s a good video and product list to combat crabgrass in a lawn without killing your grass toward the bottom of this article if you decide to stay the course and deal with any/all weeds that come up later.
      2. Apply a starter fertilizer with a crabgrass inhibitor now. There are a few that will block crabgrass from germinating while allowing your grass seeds to germinate, and a good starter fertilizer will promote root growth in your seedlings and accelerate the rate at which your new grass becomes strong and resilient. This article covers pretty much every aspect of seeding in spring, and the section on Cool Season grasses has a link to the starter fertilizer/crabgrass preventer I use and recommend. If you haven’t applied any fertilizer when you overseeded, you can do that at any time now.

      Hope this information is helpful! Thanks for reading and commenting and best of luck with your lawn this year.

  3. Jim Fruits

    I live inCincinnati area, and want to do some landscaping including new grass seed. It is now 10/11/2021. Is it too late for grass seed and /or weed control? Sjhould I wait until spring?
    Thanks

    • It’s getting close, Jim.

      If you go with something with a short germination time (Perennial Ryegrass, for example) and use a quality starter fertilizer with it when you spread the seed you can probably get a nice thick lawn established now. If you do that, I’d overseed the area with a blend of seed in the spring to thicken it up and avoid having a monoculture. That will help you establish a more resilient lawn that stands the test of time.

  4. FRANCES P FULTZ

    I live in Verona, Va I just sowed some grass seed scotts turf builder sun and shade it calls for 39 tonight with 75 tomorrow, would it help if I ncover it tonight?

    • Hi, Frances!

      Those temperatures sound just fine for your grass seed. If your daytime temperatures are in the 70s your soil temp should be just fine for germination, and it looks like new seedlings are safe from frost for the time being as well.

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