Grass seed that has not yet sprouted is extremely unlikely to be harmed by frozen temperatures. It will just wait until the weather warms up before sprouting. However, grass seed can develop mold if it is spread when the weather is shifting between freezing cold and above-freezing temperatures. Additionally, new grass seed sprouts are easily killed if they are exposed to freezing cold. So, it’s always best to wait to spread grass seed until there is no danger of a freeze.
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Will Frozen Grass Seed Still Grow?
Grass seed that has been stored in freezing temperatures over winter—such as in your garage or shed—will almost always sprout when temperatures warm up. Grass seed can remain dormant for years and survive several winters without much harm. So, even if you left a bag of grass seed in a cold woodshed over winter, you can still spread it on your lawn in spring.
- Grass seed that has been stored in freezing temperatures will not be damaged or destroyed.
- You can spread previously frozen grass seed on your lawn when temperatures warm up.
- Grass seeds that are spread in freezing weather conditions will not sprout until warmer temperatures arrive.
Grass seed will not sprout in freezing temperatures. This is a protection method developed by grass plants. Frozen ground is too hard for grass seedlings to send their roots into, so any grass seeds that sprout in freezing cold would quickly die. If you spread grass seed on your lawn while temperatures are still below freezing, don’t expect the seeds to germinate.
Should You Freeze Grass Seed Before Planting?
There is no benefit to freezing grass seed before you plant it. Grass seed does not need to experience a freeze in order to germinate later on. In fact, grass seed that is exposed to repeated freezing and thawing can develop mold that kills the seed. So, you’re a bit safer if you don’t freeze your grass seed.
- There is no need to freeze grass seed before planting.
- Grass seed that is exposed to repeated freezes and thaws can be killed by mold. This is most likely to happen if the seed has already been spread on your lawn.
- Store grass seed in a cool, dry place with a temperature 40–50℉ (4–10℃) to keep it safest.
To ensure the best germination rate for your grass seed, store it in a cool, dry place. Storage temperatures between 40–50℉ (4–10℃) are best for every type of grass seed. These temperatures are cool enough to prevent the seeds from sprouting prematurely but warm enough to prevent freezes. You’re unlikely to harm your grass seed if it is stored in extreme cold, but temperatures slightly above freezing are safest.
Will Freezing Temperatures Hurt New Grass Seed?
If you’ve recently spread grass seed on your lawn only to see freezing temperatures in the forecast, it’s important to take action immediately. If the grass seeds have already begun to sprout, the seedlings can be killed by a single frost. If you find yourself in this situation, take these steps to protect your new grass from frost.
- New grass sprouts are easily killed by freezing temperatures.
- Take steps, such as watering your lawn before a frost, to protect new grass from cold snaps.
- Grass seed that hasn’t germinated will be mostly unharmed by freezing cold.
- There is a chance that a series of frosty nights followed by warm days can cause mold to kill the grass seed on your lawn before it sprouts.
Grass seed that has recently been spread on your lawn but has not yet sprouted will typically survive a freeze without harm. However, if the ground freezes and thaws several times, this exposes the seeds to excess moisture without allowing them a chance to sprout. This is when mold growth attacks your grass seed and kills it. So, it’s best to overseed your lawn when there is no chance of frost for the next 6 weeks.
Can You Plant Grass Seed if it Freezes at Night?
Do not spread grass seed when weather conditions include freezing or frosty nights. This is a recipe for disaster. 2–3 warm days in a row will encourage your grass seed to sprout. A nighttime frost at this point will freeze the top layer of soil, starving and killing your baby grass seedlings overnight.
- If temperatures reach freezing at night, do not spread grass seed.
- Warm days and cold nights are deadly conditions for grass seedlings.
- Track soil temperatures in your area to make sure they are well above freezing before you plant grass seed.
Soil temperatures—not air temperatures—are the most important factor when deciding when to plant your grass seed. Typically, the soil is 10℉ (5℃) colder than daytime highs. So, even if the day is warm, the ground may be too cold for grass to sprout and properly take root. Seeding your lawn at this time may be a death sentence for your new grass.
What is the Lowest Temperature Grass Seed Will Germinate?
Daytime highs between 70–80℉ (21–27℃) are the lowest range where grass seed will germinate at high rates. However, the exact germination point depends on the type of grass. Warm-season grasses germinate once soil temperatures climb to 70℉ (21℃). This lines up with daytime highs that reach 80℉ (27℃). Cool-season grasses will begin sprouting once soil temperatures rise to 60℉ (16℃), which lines up with daytime temperatures of 70℉ (21℃.
- Warm-season grasses begin to germinate when daytime highs reach 80℉ (27℃).
- Cool-season grasses start germinating when daytime air temperatures are 70℉ (21℃).
- Warm-season grasses are best planted in late spring.
- Cool-season grasses grow best when the seed is spread in late summer or early fall.
If you are planting warm-season grass seed, wait until daytime highs first reach 80℉ (27℃) in spring. Sowing the seeds earlier than this puts them at risk of being killed by late frost or being devoured by flocks of birds. Cool-season grasses grow best when they are spread in fall, once summer highs drop down to 75℉ (24℃) for the first time. Make sure to spread cool-season grasses at least 6 weeks before the first average fall frost to prevent them from being killed off by cold.
Can Grass Seed Be Stored Over Winter?
You can safely store grass seed over winter. Grass seeds are biologically designed to survive winter unharmed and sprout in spring. Keep these rules in mind when exposing grass seed to freezing cold:
- Grass seed is extremely unlikely to be damaged by freezing conditions in winter.
- To completely eliminate the risk of frost and cold damage to grass seed, store it in a location that remains 40–50℉ (4–10℃) throughout winter.
- Do not spread grass seed when the weather is freezing.
- Grass seed that has already been spread on your lawn can be damaged if it is exposed to repeated frosts and thaws.
- New grass sprouts can be killed by frost.
- Grass seed germinates best when daytime highs are 70–80℉ (21–27℃). Wait until these temperatures arrive before seeding your lawn.
With these tips in mind, you can keep your grass seed safe in cold weather. After all, there’s not too much to worry about. You can store grass seed in a garage or basement in northern climates with very little risk of harm to the seeds. Once warmer temperatures arrive, it’s time to use those seeds to add more green grass to your yard.