Can I plant grass seed in 90 degree weather?
High heat prevents cool-season grasses like turf-type tall fescue from germinating properly and stresses young seedlings. Tossing seed down now without waiting for temperatures to drop below 85 or 90 degrees usually results in wasted seed and dead grass, which is why many landscapers choose to postpone seeding until late September.
What people tried
Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.
- 1Waiting until temperatures stay below 85 or 90 degrees before seeding
- 2Watering frequently throughout the day (four times a day for five minutes)
- 3Switching from impact sprinklers to rotary sprinklers
- 4Increasing frequency of daily watering cycles
- 5Replacing coco coir with traditional soil or peat
- 6Watering twice a day instead of three times due to time constraints
- 7Rescheduling the seeding date
- 8Shallowing watering them about 5 times a day
- 9Laying down some Peat moss before germination
- 10Laying down some more seed next week
- 11running irrigation up to 5 times a day
- 12covering the area with straw
- 13watering every 1 to 2 hours for short intervals
- 14using a slit seeder for bare areas to help shield from the heat
- 15Watering frequently (multiple times a day) to help seeds survive high temperatures
- 16Proceeding with seeding immediately despite the heat and adjusting soil amendments later
- 17Delaying seeding until temperatures break or seeding later in the season
- 18Using weekly morning watering
- 19Applying organic fertilizers and aeration
- 20Adding gypsum
- 21Applying disease control products
- 22Mowing at a higher setting with sharpened blades
- 23Using grub killer
- 24Keeping it watered and hoping for cooler weather
- 25Watering at night using an in-ground sprinkler system to offset temperature issues and frost risks.
In their words
Unedited, most upvoted first, each linked to the thread it came from.
“What’s done is done but just looking for some reassurance that I haven’t made a mistake.”source ↗
“Did I make a mistake by seeding this weekend or did I make the right decision?”source ↗
“Planning on reseeding and getting it going again I have TTTF but we're still getting 90-92 degree days can I just toss it down and water or do I need to wait till end of september when temps stay below 85.”source ↗
“I recently moved into a new place and they put down sod for us but now it’s dying?”source ↗
“I haven’t cut it because that seemed to make it worse??”source ↗
“Same general location also using TTTF. Original plan was to dethatch, aerate, top dress, and seed the 17th but Im considering postponing the seeding until the heat is consistently below 90 degrees.”source ↗
“Coco coir on top of new seed, appears to be drying SO fast!”source ↗
“By the time I the 4th one finishes, the soil is already dry on the first area at least on the outer edges.”source ↗
“I can’t imagine going 4 hours between waterings as my soil dries out in less than an hour?!”source ↗
“Lawn Company I use for seeding and aeration insisted it was totally fine and probably better to go ahead with seeding on Monday 14th. This seems to hot no? We are also on a water restriction in Charlotte. It’s a bluegrass fescue seed”source ↗
“Then the forecast changed to 95ish all this week.”source ↗
“will they be able to survive the next 4-5 days of intense heat?”source ↗
“I’m in the same boat as you.”source ↗
“my direct sunlight areas are barely patchy and I’m not happy with the germination so far”source ↗
“Definitely jumped the gun on seeding this year”source ↗
“we have irrigation but I hear even with that it might be too hard to keep seeds moist”source ↗
“as you can see, it’s still hot as blazes here in Volunteer country!”source ↗
“I am watering my back yard every 2 hours for 3 minutes and the front every hour for 5. I am praying the front germinates. It is showing signs in some areas, but I fear I will have to reseed in two weeks.”source ↗
“Given this god awful heat dome, what is your sequence and timing starting to look like?”source ↗
“I think I'm running out of time to wait for a meaningful break in temperatures, then try to soil test, spray, aerate, seed, and fertilize before the bottom drops out.”source ↗
“I'm in a similar boat, just gonna go for it and water like crazy.”source ↗
“I am struggling to fix the lawn for past 3 seasons.”source ↗
“pretty much no grass grows ( except for short time in fall and spring) mostly white dead grass that just peels off and weeds take over whole summer.”source ↗
“after every mow there are brown patches underneath .”source ↗
“Very frustrated and need your help.”source ↗
“This year, average ground temperatures are still running in the 80's and air temperature has been mid-low 90's.”source ↗
“Based on all my research, I'm at the last recommended window to drop seed. Cool season grass (tall fescue). How long can I realistically wait?”source ↗
Where this came up
People with this problem also raised
- 86Why is my overseeding failing to grow?
- 3Should I use a fungicide on brown grass during high humidity?
- 17How to keep a lawn green during a drought with water restrictions
- 18Can you plant grass seed late in the season after missing the window?
- 10How to water new grass seed with a full-time job
- 16How to fix a dead lawn on a new house without experience