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. Else, your grass seedlings will be fighting against weed competition, dormancy, and slow germination. These hurdles can quickly kill a young lawn.
Grass Dormancy In Warm Seasons
Warm season grasses should, ideally, be sowed in the spring. Most grasses of this type 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 last frost of winter, there is a greater chance the seeds become dormant until their preferred soil and air temperatures come back. The seeds then become fodder for birds and squirrels, and this makes your lawn more susceptible to erosion.
Grass Dormancy In Cold Seasons
By nature, cool season grasses are durable and hardy. 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 result in dormancy. If these seeds are sowed before the final frost, the warming temperatures will encourage the seeds to germinate and begin sprouting; however, the next frost will effectively kill the young grass. Seedling grass does not have the established root system to store critical moisture and nutrients for the more stressful growing conditions.
Failure to Germinate
Under the preferred conditions, grass seed will generally begin to germinate after 14 to 21 days of contact with prepared soil. Sprout emergence is aided by warm temperatures and proper amounts of water. However, if seeds are sowed before the season’s final frost, germination can be slow to occur or halt altogether. 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. This problem can easily be avoided by waiting to lay down grass seed until the last frost.
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 final 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. The final frost effectively kills growing weeds, so that your new grass can grow unimpeded.