The Big Freeze! How to Protect Grass From Frost & What to Do

Once you’ve seen your yard and garden through the heat of the summer, the work doesn’t stop there.

The chills of winter bring new challenges, and it’s important you prepare for the tough season ahead.

Particularly when it comes to your lawn.

A blanket of frost in the morning is one of the earliest signs that the cold is on the way.

And while it might look nice, it can cause damage to plants and grasses.

In this article, we take a look at how to protect grass from frost, and the ESSENTIAL practices you need to do NOW!

(If “now” is early October to early November!)

Frost on Grass – Too Long, Didn’t Read

If you’re in a hurry to find out how to protect your grass from frost – we’ve got you covered, right here:

Follow these four main points before, during, and after a cold snap sets in.

Care should be taken when protecting all your plants from frost, so stay with us as we explore each tip in more detail.

What is Frost?

Chinese military strategist Sun Tzu might not have been talking about frost when he wrote about “knowing your enemy,” but it’s an important lesson, nonetheless.

In order to defend against something, it’s vital to understand it.

So, let’s go back to school for a brief moment.

Frost is a thin layer of ice that forms on solid surfaces. It occurs when water vapor in an above-freezing atmosphere comes into contact with a solid surface that is below freezing.

These conditions typically occur when you have clear skies, and little to no wind. The earth’s surface, (and vehicles, buildings, trees, and other objects) loses heat rapidly, allowing a layer of super-cooled air to develop in its place.

Add moisture to this, and ice crystals form. Voilà! You have frost!

But did you know there are several types of frost that can occur depending on the conditions?

The most common include:

The National Geographic offers a wonderful article on Frost, and you can explore all the different types there. But the one we’re most interested in, is radiation frost.

This is the type that most commonly forms close to the ground.

When the temperature is low enough, it can freeze the water in the cells that make up plant tissue. This is commonly known as “frost damage.”

Plants that have been subjected to serious frost-damage stand little chance of recovery.

Case in point – this heartbreaking death:

We recently lost a beautiful peace lily that was left outside when a sudden and unexpected frost hit in the morning.

We tried everything we could to revive it, but the shock of the frost left it with absolutely no chance of coming back. Trust me – it was a pretty tough moment, and would be for any plant and nature lovers.

That’s why it’s important to stay vigilant and make sure your plants are prepared, and you don’t leave anything out in the open that isn’t going to be able to handle it.

Farmers certainly don’t take the risk.

Did you know? As a defense against frost, some farmers employ wind machines to stimulate the air over their crops, thus helping to prevent a cold layer from forming.

Plants vs Frost

How frost reacts with plants depends on a number of factors, including the type of plant, how low the temperatures are, and the amount of tissue exposed.

Certain plants are impervious or more resilient to frost, and may even benefit from an icy dusting each year. This includes root crops, leafy greens, and cruciferous vegetables – such as cabbage and cauliflower.

But what about lawns vs frost? Who comes out on top?

Grass gets some of its nutrients from the water it takes in through its blades – but a frost can literally freeze this, and stop the process. When the ice expands, the plant’s cellular structure is compromised.

Damage then occurs when anything heavy is placed on the grass, such as a passing foot or even paw print. Grass blades can effectively snap, rather than bounce back as they normally should.

A light frost won’t freeze the ground, however, and the grassroots should be fine. Unless it’s a particularly brutal winter, your grass will recover.

But that doesn’t mean it couldn’t do with a little help.

Will Frost Kill New Grass Seed?

If you’ve been doing a spot of overseeding in your lawn (and you can follow that link for general tips), then you will be justified in your concern for the new grass as those frosty mornings set it.

Grass is going to be at its most vulnerable as it begins to germinate and tries to become established, and if it gets a sudden shock of frost it might not make it through.

However, unless it’s a particularly “hard” frost, the seeds themselves won’t be damaged. The seed will rather remain dormant, and germinate as soon as the temperatures rise and become more suitable for growth.

It’s when the grass has sprouted free from the seed husk that it really becomes susceptible to frost damage.

Either way, let’s take a look at how to protect grass seedlings from frost. And you can also read this article on the different types of grass species available for when you’re overseeding.

Alternatively, you might want to try other forms of lawn maintenance/building a new lawn. Laying sod is one way to escape the problems of fresh seed – but it’s not without its downsides, too.

Another method is to try grass plugs – and you can follow that link to find out more.

Protecting Your Lawn From Frost

Below, you’ll find a series of pro-tips that will help you to protect your lawn from frost, if you think that a cold snap is on the way.

A particular emphasis has been placed on new seeds, as they will be very susceptible to frost damage in the early stages of life.

Irrigation

This tip often comes as a surprise, as you might think adding moisture when a frost is on the way is counterintuitive. Water freezes, after all!

Not so, as a deep watering of your lawn can actually help the grass resist the frost, as wet soil retains heat better than dry, and water acts as an insulator. This can then prevent the ground from freezing.

Once or twice a month is sufficient during fall/early spring – ideally, the night before a suspected frost takes hold.

Water will then evaporate slowly overnight, and this process helps keep the air warm around the grass blades, and a frost is more likely to be avoided.

This article on how to properly water your lawn offers some general advice for an annual irrigation schedule, but you can also check out our complete month-by-month lawn care guide.

Cover Seedlings

New grass seeds struggling to become established are vulnerable to frost, so it’s a good idea to cover these areas before a cold snap.

However, I’m not talking about using a tarp or other such material – as that can cause more harm than good.

Adding a top dressing of organic fertilizer or peat moss can help insulate a new lawn, as well as giving it a boost of micronutrients at the same time.

Check out this article on DIY fertilizers for advice on how to make your own. It starts with investing in a good compost tumbler!

And there’s no need to worry about the fertilizer itself, as it will continue to provide its nutrient boost when the right conditions are met. See our FAQ section below for more information.

Remove Debris

Try to keep on top of the leaf situation on your lawn – or if there’s any other kind of debris covering the grass. Too much material can smother it.

That said, there’s a school of thought that “leaving the leaves” is a good idea, and it can help boost the lawn’s health, keep it insulated, and provide a home for helpful critters through the winter.

Likewise, don’t mow your lawn in times of frost. As much as you shouldn’t mow when it’s wet, don’t mow when the grass is brittle with the cold.

Keep Off the Grass!

Frost alone might not be enough to kill a plant, but walking on frosted grass certainly can – particularly new seedlings.

Frozen molecules of water within the grass will tear the organism’s tissue under stress – such as when a pair of size 11s clomps across the lawn.

Try to keep vehicle and foot traffic off your lawn throughout winter, or down to the bare minimum at the very least.

Even our four-legged friends can cause damage when running around on a frosty lawn – so keep them indoors, and/or find an alternative place for them to run riot.

If you do need to walk on the grass, then try to wait until the sun has melted the frost.

You can attempt to speed this process up by watering the lawn with warmer water, although this might not be possible depending on the temperature.

Lawn Frost Damage – Signs to Look For

Frost damage varies depending on the type of plant that it has affected, and this includes the species of grass in your lawn.

Cool-season grasses tend to be more resilient to frost than their warm-season counterparts, although the likes of perennial ryegrass, annual ryegrass, and tall fescue aren’t that great.

For warm-season species, Bermuda grass will start to appear brown and patchy with frost damage and will be in trouble through extended periods of cold weather.

The same can be said for St Augustine, which also becomes discolored, and can turn shades of yellow and even purple after a harsh frost.

Grass that has been walked over during a frost can appear crushed or snapped. This might be accompanied by a whitish hue and other discoloration.

Once again – that’s exactly why you need to do your best to stay off your grass during frosty conditions.

Treating freeze and frost damage on your lawn depends on the species you have, but in most cases, it should be able to bounce back.

Read on for tips on how to help it do just that, and don’t forget to make sure you have all the lawn care tools you need to stand the best chance of success.

Lawn Care After Winter

When the snows finally melt and something that resembles a shade of green returns to your yard, it can be an exhilarating time for gardeners gearing up for the spring.

And lawn care enthusiasts also need to use the time effectively, so their labor of love stands the best chance of recovery.

A proper regime of dethatching and aeration is going to give you the best chance of lawn recovery, and you can follow those links for full how-to guides to each process.

You might notice that your lawn has developed a few unusual lumps and bumps over winter – as a result of the freeze/thaw cycle.

Otherwise known as frost heave, this movement of the soil can result in an uneven yard. Consider using a lawn roller in the spring to even things out.

This article on lawn care after winter will also tell you everything you need to know when it comes to waking your grass up from its wintry slumber.

And you can watch the helpful video below, which offers a general guide for keeping your plants protected in frosty/freezing conditions.

FAQs

Does frost kill weeds?

Unfortunately, native weeds and other undesirable plants in your region will likely have adapted to colder climes and should be quite resilient to frost.

However, it’s not exactly great for them either, and a March frost will hamper their growth and recovery, for example.

Winter itself, on the other hand, is a different story. Check out this article that asks do weeds die in winter? It also has some tips for preventing undesirable plant life from coming back in the spring.

Does frost affect fertilizer?

Great question! When you’re trying to boost the health of your lawn, dispensing an appropriate fertilizer (click this link to learn about the different types) can be very beneficial.

But is fertilizer affected by frost?

No, is the short answer. The grass will be in a phase of little or no growth, but the fertilizer itself will not be impacted by the freeze. The nutrients contained within will still feed the soil and grass when temperatures increase.

This article on when and how to fertilizer your grass will tell you more.

It’s also worth noting that a seaweed fertilizer can help boost a plant’s resistance to the cold – so check out that link on seaweed vs fish ferts if you fancy trying that on your lawn.

Should I water a lawn after frost?

You should try and keep your grass hydrated, but never water when the ground is frozen or frost is still present.

It’s possible to continue watering your lawn until this occurs, usually in late fall.

Will one night of frost kill new grass?

It won’t damage the grass seed itself, but if you have newly germinated seedlings, it’s highly unlikely that they will survive such an early stress test.

Will a frost kill grass?

Again, unless you’re talking about new grass, a frost alone isn’t enough to kill your lawn. But it can be badly damaged from foot traffic or other issues when it’s so brittle.

As such, it’s important that humans and pets remain off the turf as much as possible during this time.

How do you protect new grass from freezing?

The most obvious way of protecting new grass from freezing is to be sure to plant it well before the first frost arrives.

If that time has already passed, you can try covering your new seeds the night before a frost is expected. Use a large tarpaulin or similar sheeting.

Just remember to take it off in the morning so sunlight, moisture, and other nutrients can get to the seed.

Finally, you can try watering the area (but not too much). Water will act as an insulator and actually keep the ground warm, rather than being dry and exposed to the elements.

At what temperature does grass get frost?

Grass and other plants will develop frost when temperatures are 32 degrees Fahrenheit and below.

But remember that heat rises, and so the ground might be much colder than the air temperature your thermometer is reading.

That’s why, even if you think it’s above 32 degrees, you can still see frost on your lawn.

Is it better to leave your lawn short or long for winter?

Good question. Contrary to leaving your lawn longer to protect it from the heat of the sun in summer, during winter you should mow it relatively short.

This is so snow mold and other pests and diseases don’t have a chance to develop.

You don’t need to get out the measuring tape, but around 2-2.5-inches is ideal for your final mow of the season.

Read this complete article on mowing heights through the seasons for more information.

Summary

A brisk, frosty morning can be one of life’s simple, seasonal pleasures, but it can also play havoc with unprotected plant life in our yards and gardens.

Particularly when it comes to new lawn care.

I hope this article has armed you with the knowledge for how to protect grass from frost. Let us know if you have any further questions, or perhaps you have some frost-defense tips you’d like to share?

Stay safe out there, stay warm, and happy gardening!