Timing is everything with grass seed. Plant at the wrong time and you waste money. The seed either never sprouts or sprouts and dies. I have made both mistakes.
Here is exactly when to plant grass seed based on where you live and what grass you are planting.
The Golden Rule of Grass Seeding
Plant when soil temperature matches the grass type. Cool-season grasses need soil at 50 to 65 degrees. Warm-season grasses need soil at 65 to 75 degrees. Check soil temperature, not air temperature. Soil changes slower than air.
You can check soil temperature for your zip code at Greencast Online. Or stick a soil thermometer two inches into the ground. I do both.
Cool-Season Grass Planting Windows
Cool-season grasses grow best in spring and fall. But fall is better than spring for seeding. Here is why.
Fall seeding gives grass two cool growing seasons (fall and the following spring) before summer heat arrives. The grass has time to develop deep roots. Spring seeding only gives grass one season before summer stress hits.
Fall seeding also faces less weed competition. Most weeds sprout in spring. Fall-seeded grass gets a clean start without fighting crabgrass and dandelions.
Cool-Season Seeding by Region
| Region | Best Fall Window | Spring Backup |
|---|---|---|
| Northeast | Aug 15 to Sep 30 | April 1 to May 15 |
| Midwest | Aug 15 to Oct 1 | April 1 to May 15 |
| Pacific Northwest | Sep 1 to Oct 15 | April 15 to June 1 |
| Transition Zone | Sep 1 to Oct 15 | March 15 to May 1 |
The transition zone is the hardest place to grow grass. It stretches from Maryland through the Carolinas, across Kentucky and Tennessee, and into Oklahoma. Summers are too hot for cool-season grasses. Winters are too cold for warm-season grasses. Tall fescue is the best bet here.
Warm-Season Grass Planting Windows
Warm-season grasses must be planted in late spring or early summer. The soil must be warm. Air temperatures must be consistently above 70 degrees. Night temperatures matter too. If nights dip below 55, warm-season seed sits and rots.
Warm-Season Seeding by Region
| Region | Best Window | Grass Types |
|---|---|---|
| Southeast | April 15 to July 15 | Bermuda, Centipede, Zoysia |
| Deep South (FL, TX) | March 15 to June 30 | Bermuda, Bahia, St. Augustine |
| Southwest Desert | April 1 to June 15 | Bermuda (with irrigation) |
| Southern California | March 15 to June 15 | Bermuda, Zoysia |
Spring vs Fall Seeding: The Real Difference
I seeded in spring for years because I was impatient. Every spring seeding struggled. The grass came in thin. Weeds competed hard. Summer heat killed off weak seedlings. By August I had bare patches again.
Then I tried fall seeding. The difference was dramatic. The grass came in thicker. Weeds were minimal. By summer the grass had strong roots and handled the heat without problem. Fall seeding takes more patience but gives better results. Every time.
Frequently Asked Questions
Can I plant grass seed in summer?
You can, but it will be an uphill battle. Summer heat stresses seedlings. Weeds grow aggressively. You will need to water three to four times per day. For cool-season grasses, wait until fall. For warm-season grasses, summer is the normal planting time.
What happens if I plant grass seed too early?
If soil is too cold, seed sits dormant and may rot. Cool-season seed planted before the soil reaches 50 degrees will not germinate. Warm-season seed planted before soil reaches 65 degrees will rot. Wait for the right soil temperature.
Can I plant grass seed in winter?
You can dormant seed in late winter when the ground is frozen. The seed sits in the soil and germinates when temperatures warm in spring. This works for cool-season grasses. It does not work for warm-season grasses. Dormant seeding is risky. Spring rains can wash seed away before it germinates.
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