Snow will not kill unsprouted grass seed. Most grass plants drop their seeds in fall. The seed then safely sits dormant during cold weather and only sprouts once the weather warms up. So, if your grass seed hasn’t germinated yet, snowfall won’t harm it. However, newly sprouted grass seedlings are easily killed by snow and frost.
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What Happens if You Plant Grass Seed and it Snows?
If you’ve overseeded your lawn and experienced an out-of-season snow flurry, your grass seed is likely still fine. Depending on the species of cool-season grass, most varieties take anywhere from 5–15 days to germinate in warm soil conditions. If the seeds are spread on cold soil, or if snow lands on the soil after you spread the seed, this will cause the seeds to stay dormant. Once conditions warm up and stay warm for several days, the seeds will sprout.
- Grass seed that has not sprouted will not be harmed by snow cover.
- Grass seed requires 5–15 days of warm, moist soil conditions before it sprouts.
- In most cases, snow will simply delay the time until your grass seed sprouts.
If the seeds have already begun to germinate (sprout) then a late spring or early fall snowfall is very dangerous. Young seedlings that have not yet developed deep roots are easily killed by frost, snow, and freezing soil temperatures. It’s important to take the right steps to protect grass seed from frost and snowy conditions.
Does Snow Kill Grass Seedlings?
Newly sprouted grass seedlings are at risk of being killed by snow and frost during the first 6 weeks of their life. The beginning stages of a grass’ life cycle are the most delicate. The fragile roots of new grass seedlings are destroyed by cold weather and frozen ground. An out-of-season snowfall can kill seedlings of both cool and warm-season types of grass.
- Snow and frost can kill grass seedlings that are less than 6 weeks old.
- In fall, plant grass seed 6–8 weeks before the average first fall frost.
- In spring, plant grass seed 2 weeks after the average last spring frost.
Because new grass seedlings require warmer temperatures for survival, it’s important to seed your lawn at the right time to prevent cold weather from killing your seeds. If you’re seeding in the fall, spread the seed at least 6–8 weeks before the first average fall frost. If you’re seeding in spring, wait 2 weeks after the average last spring first before seeding.
What Happens if Grass Seed Freezes?
Grass seed typically won’t be harmed by freezing temperatures. Grass seed is biologically adapted to withstand snow and ice. It will sprout once the soil surface is warm and moist enough for seedlings to take root. If it isn’t eaten by birds or ruined by fungus, grass seed can withstand freezing temperatures for several months.
- Grass seed will still sprout after it has been frozen.
- Even several months of snow and ice won’t harm grass seed.
If you spread a dormant grass seed in fall and freezing temperatures arrived before your seeds could sprout, there’s a good chance that some of that seed will sprout in spring. Grass seed stored in freezing conditions will still be ready for planting in spring.
Can You Plant Grass Seed on Top of Snow?
Some cool-season grass seed is so snow-tolerant that you can even get good results by planting grass seed in winter. Although you should usually avoid planting grass seed on top of snow because it will often be eaten by birds and other pests, seeding grass seed on frozen ground is a great tactic. Once the cold weather breaks, the grass seed will germinate. This means you’ll get new grass earlier in the year.
- You can spread grass seed on frozen ground during winter and have great success.
- Avoid spreading grass seed on top of snow when possible—seed on top of snow is easy pickings for birds.
- For best results with winter seeding, spread grass seed in February or March.
When winter-planting grass seed, it’s best to spread the seed in late winter. Grass seed spread on frozen ground in February or early March has a far better chance of sprouting in spring versus grass spread in December or January.
Will Ground Frost Kill Grass Seed?
Grass seeds typically won’t be damaged by frost. Even warm season grasses such as Bermuda and St. Augustine spread seeds can survive freezing temperatures. The seeds will simply lay dormant until the weather warms enough to provide a safe environment for young grass. On the other hand, newly sprouted grass can be killed by frost or snow. To prevent your baby grass from being wiped out by a freeze, seed your lawn in fall well before the first average frost. Then, wait until the danger of frost has passed before you seed your lawn in spring.