Can Grass Seed Freeze?

In short, the answer is yes.

Although most homeowners are eager to get a jump on starting their spring lawn, the results may not be what they were expecting. If your grass seed is sowed too early in the season, there is a higher chance of failure.

Most experts recommend waiting to plant spring grass seed until after the final frost has occurred. Or else, your grass seedlings will be fighting against weed competition, dormancy, and slow germination.

These hurdles can quickly kill a young lawn.

In a perfect situation, it’s best to not seed in the spring at all (if you have a cool season lawn).  The best time of year to seed is in the fall [1].

Grass Dormancy In Warm Seasons

Warm season grasses should, ideally, be sowed in the spring.

Most warm season grasses prefer soil temperatures that are around 75 degrees Fahrenheit or higher. If exposed to cooler temperatures, most warm season grasses will, by default, revert to dormancy.

Since cold weather poses a survival threat to warm season grass, their natural instinct is to put off germination until the warm weather returns. If you sow seed before the soil temperatures warm up, there is a greater chance the seed will become dormant.

The seeds then become food for birds and squirrels which defeats the purpose of seeding in general 🙂

Grass Dormancy In Cold Seasons

By nature, cool season grasses are more durable and hardy than warm season grasses. Most types prefer soil temperatures ranging from 55 to 75 degrees Fahrenheit.

Exact soil temperatures will vary depending on which climate zone you live in. Conversely, if the soil temperature drops below 50 degrees F, the majority of cool season grasses will start to go dormant.

If these seeds are sowed before the final frost, the warming temperatures will encourage the seeds to germinate and begin sprouting.

It is important, however, to get the seed down and germinating 4-6 weeks before the first frost.  Frost will kill off seeds that haven’t germinated and grass that hasn’t had time to mature.

Seedling grass does not have the established root system to store critical moisture and nutrients for the winter months.

Failure to Germinate

Under the preferred conditions, grass seed will generally begin to germinate after 7 to 14 days of contact with prepared soil.

Sprout emergence is aided by warm temperatures and proper amounts of water.

Depending on the type of grass seed you’ve laid down, some seeds will remain inactive, while others sprout. What you’re left with is spotty grass coverage, which will leave your lawn susceptible to water and wind erosion.

It’s important to get as many of the seeds to germinate as possible.  Just make sure to keep the soil moist and not pile on the seed too thick – you don’t want it to bunch up too much as this will also prevent germination.

The Danger of Weeds

Unfortunately, weeds often have a broader germination temperature range than grass seed does.

Grass seed that sprouts before the winter’s first frost will be forced to compete for space and resources with emerging weeds.

Weed growth tends to be aggressive, and it can rob your grass seed of the vital moisture and nutrients your helpless grass needs to thrive.

That being said, there are a few ways to prevent weeds from taking over your newly planted grass.

  • Tenacity is a good product to put down at the same time as seeding
  • You can also weed by hand, but be careful to not compact the soil too much as this will hinder germination
  • Make sure the soil is properly prepped before seeding
  • Use a high quality grass seed that does not contain filler or weeds.

Also make sure to store unused grass seed in a cool, dark area.  You don’t want it to get too cold that it freezes.