Will Frost Kill Grass Seed And How To Protect Them? The Ultimate Guide

If you plan to seed or reseed your yard, you probably already know that you must plant grass at the right time of the year for the best chances of success. And, in most parts of the country, early spring and fall are often the best times to do so.  However, these seasons often come with a risk of frost, especially in the northern states. So, what should you do, and can new grass seed survive a frost?

Can new grass seed survive a frost

Photo Credit Should you worry if you have recently seeded your lawn and an unexpected cold spell is in the forecast?

Simply put, grass seeds can survive cold weather and frost. They go dormant when the temperature is below optimum for seed germination and grass growth. However, while the grass seed can survive frost, grass seedlings cannot, and you should not plant grass seed when there is a chance of snow in the forecast.

But what if you have planted grass seed, and it starts snowing?

First, do not panic, and read on to find out!

Can Grass Seeds Survive A Frost?

Can Grass Seeds Survive A Frost?

Photo Credit Avoid extremes! It is best to avoid sowing seeds if there is a run of frost or snow.

Grass seeds are hardy and can tolerate freezing temperatures without significant harm. So, frost will not kill any grass seeds that have not yet germinated. However, germinated grass seeds that have recently sprouted are highly vulnerable to cold temperatures.

Grass seeds that have not yet germinated go dormant when exposed to frost, but a sprouted seed, i.e., a grass seedling, cannot do that.

So, when its small roots are exposed to freezing temperatures, the delicate young plant immediately gets destroyed.

RELATED: How Long Does It Take For The Grass Seeds To Grow? Growing Grass The Easy Way!

Just How Cold Does It Have To Be Before Grass Seed Dies?

Grass seeds are biologically designed to survive winter and sprout in summer.

It means they are very well-adept at surviving cold temperatures, and it has to be extremely cold before grass seeds start dying. The seeds of many grass species can even survive temperatures as low as zero degrees Fahrenheit  (-18 degrees Centigrades).

Whereas grass seedlings (newly sprouted grass) are much more delicate when it comes to surviving the cold weather, as already stated. And, when the temperature hits about 32 degrees Fahrenheit  (zero degrees Centigrades), it freezes the topsoil.

And, when the topsoil freezes, the young grassroots freeze too, starving the seedling and leading to its death. Even a single cold night is enough to kill a seedling.

Should You Protect Grass Seeds From Frost?

There is no need to protect grass seeds from frost. Grass seeds stored in your garage or anywhere else with subzero temperatures will not be harmed. Likewise, the ice will not damage grass seeds lying on your lawn that have not germinated yet.

When the cold temperature hits, grass seeds that have not yet sprouted will go dormant. But, when temperatures become favorable, they will grow.

So, what about grass seedlings? Should you protect them from frost?

Well, yes! You will need to protect seedlings from frost if your seeds have germinated and there is a frost prediction in the coming days. Continue reading to find out how!

RELATED: How To Plant Grass Seeds On Hard Dirt For Best Results? A Simple & Easy Guide

How To Protect Grass Seedlings From Frost?

How To Protect Grass Seedlings From Frost?

Photo Credit Walking or driving across young, frosted grass can kill the grass.

Avoid weather extremes! Do not plant grass seeds when it is too cold or when a frost is expected in the upcoming few days. But if you have already planted grass seeds and there is a prediction of snow in the weather forecast. First of all, do not panic.

Second, follow these tips to keep the seedlings alive and thriving.

Water The Lawn

It may seem counterintuitive, but watering your lawn right before a frost will keep the soil from freezing and help protect your grass seedlings from the ice.

Water has the highest specific heat capacity of any liquid. It means that it requires quite a bit of energy to change its temperature by one degree Celsius. So, if there is water in the soil when it is about to snow, the ground and the seedlings will be less likely to freeze.

For best results, water the grass in the evening to protect it from freezing overnight.

I would even suggest you go the extra mile and program your sprinkler system (if you have one) to water your newly seeded lawn for about half an hour every three hours.

The water from the tap is typically 15 to 25 degrees above freezing, and adding warm water continuously to your lawn will keep the topsoil from freezing and protect your grass.

Cover The Lawn

If you have sown your grass seeds relatively late and instead of going dormant, they surprise you by sprouting mid-winter, you can protect them from frost by covering the lawn with mulch. It is one of the best ways to protect seedlings from freezing to death.

For this purpose, you can use a tarp which you can put on the lawn during the evening. It will help the ground preserve heat during the night, keeping it from freezing.

You can even use clothes, newspapers, or a thick plastic sheet. However, whatever you use, hold it down with stones or weights to prevent the wind from blowing it off. But please take off the covering during the morning to help your seedlings breathe.

Also, taking the tarp off during the day will help the ground absorb some sunlight which makes the soil warm, and thus the temperature at night will stay hotter too.

Stay Off The Lawn

Even if your grass is not new or the ground is not frozen, an essential part of winter lawn care is to keep foot or vehicle traffic off the lawn.

Nothing damages the grass like foot or vehicle traffic when it has frozen. When you walk on frozen grass blades, they can snap; even if they do not crack, ice crystals inside them will cause harm.

So, when you have planted grass seeds in the turf, and they sprout mid-winter, keep off the lawn until the grass has had enough time to establish itself and thaw.

However, if you have to walk across your lawn, I suggest you place some stepping stones in it. It will help you navigate the yard without harming or killing the seedlings.

RELATED: Pros And Cons of Using Straw To Cover Grass Seed In A Newly Seeded Lawn

Lastly, Plant Grass Seeds On Time

Can new grass seed survive a frost

Photo Credit If you plant your grass seed at the right time, the seedlings will have the best chance of survival.

It would help if you planted your grass seed when the weather is perfect for its growth. The perfect timing, however, will vary from place to place and the grass species you will plant. 

Fall Grass Seeding Timing

Fall grasses include tall fescue, perennial ryegrass, fine fescue, and Kentucky Bluegrass.

These grasses are also known as cool-season grasses and grow best in the country’s northern parts. They grow best when they are planted in fall, hence the name.

However, you cannot plant cool-season grass seeds anytime in the fall. You have to get the timing right, or the chances of germination will be significantly reduced.

For example, you must ensure that you plant the grass seed at least six weeks before the first expected frost of the season. Also, ensure that the soil temperatures have dipped below 70 degrees Fahrenheit  (21  degrees Centigrades) before you seed your lawn.

It will ensure that your grass seeds have had enough time to establish themselves in the ground before the winters arrive and everything goes dormant.

However, do not seed too early, either. If you plant too early, the grass seed will be exposed to summer heat, and it can quickly dry and kill your new grass seedlings in the ground.

Spring Grass Seeding Timing

Spring grasses include Bermuda grass, Bahia grass, and St. Augustine grass.

These grasses, also known as warm-season grasses, grow best in southern parts of the country. The best time to plant them is in spring, hence the name spring grasses.

Warm-season grasses are the most likely to be damaged by frost. It would help if you only planted them when the soil temperatures exceed 70 degrees.

Do not plant them too early in the fall, or the cold will kill the seedlings.

Final Thoughts

For a healthy lawn, year-round care is essential, including performing different lawn activities at the right time of the year.

So, when seeding your property, you must ensure that you do it when the seedlings have a maximum survival chance. And, when planting in fall, frost is the biggest threat your germinating seeds and grass seedlings face.

Therefore, ensure that you plant the grass seed when there is no threat of frost because even though the grass seeds themselves can survive the frost, seedlings cannot.

Frequently Asked Questions (FAQs)

What is dormant sowing?

The process of planting grass seed in the winter with the expectation that it will remain dormant until the temperature rises in the spring is referred to as “dormant sowing.” A coating of snow can help to preserve it in this condition.

Can you plant grass seed before a frost?

It would help if you planted grass seeds at least six weeks before the first expected frost. That way, grass seeds will have enough time to establish themselves before winter arrives.

Does straw protect grass seed from frost?

Many people use straws to cover their newly seeded lawns in the winter. A thin layer of pine straw or needles provides excellent insulation and keeps the soil temperature warm.

Can I mow after frost?

You should not mow your lawn immediately after a frost. If you do that, you will risk damaging or killing your grass. Instead, it would help if you waited for the grass to thaw and dry.

Sources for Further Reading

Frost Seeding Legumes and Grasses into Established Pastures. University of Wisconsin-Madison Division of Extension. (2023). Retrieved 4 January 2023, from https://fyi.extension.wisc.edu/forage/frost-seeding-legumes-and-grasses-into-established-pastures/

Frost Seeding | Master Grazer. The University of Kentucky Extension. (2023). Retrieved 4 January 2023, from https://grazer.ca.uky.edu/content/frost-seeding

Frost Seeding Pastures and Hay Fields. The University of Illinois Extension. (2020). Retrieved 4 January 2023, from https://extension.illinois.edu/blogs/good-growing/2020-03-06-frost-seeding-pastures-and-hay-fields

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