Mow a Frozen Grass

Can You Mow Frozen Grass?

In Lawn & Garden, Lawn Care, Winter by Jamie

Sometimes, an early freeze may catch you and your lawn by surprise. You want to give your grass one last cut before its long winter’s nap, and then you wake up to find the temperature has dropped and the lawn is covered with frost. Even worse, sometimes snow and ice arrive early, and that will make any further mowing impossible.

You cannot mow your grass when it is frozen, as it can seriously damage the plants and in some cases kills them. Once temperatures are consistently below 40°F (4.5°C), it’s better to put up with a shaggy lawn until spring.

Does Mowing Frozen Grass Damage Your Lawn?

Mowing frozen grass is extremely damaging to your lawn. When the grass blades are frozen, they are very brittle. Cutting them will rupture the cells, and the pressure from walking on the lawn, as well as the weight of the lawnmower itself, can cause even worse damage. In some cases, you can end up severing the blades from the roots, which can kill the whole plant. There are no circumstances under which mowing your lawn when the grass is frozen, even by a light frost, is a good idea.

What Does Frost Do to Grass?

When grass gets hit by frost, the water in the blades expands and bursts the cells, damaging the parts of the plant above ground. This is normal, and grass plants have evolved to survive this. If the ground isn’t frozen, the roots can work to heal the damage, but if you walk on the lawn, the connection between them can be broken. Without the blades providing food to the roots through photosynthesis, there’s a good chance that the whole plant will die.

Learn if grass grows in the winter in our detailed article here

Is it Dangerous to Mow a Frozen Lawn?

A frozen lawn

Mowing a frozen lawn can be dangerous not just to the grass, but also to you. Ice creates a slick surface that can lead to mishaps and possibly injury. Especially if you are mowing on a slope, you can slip and fall on the frozen surface, which could lead to being injured by your mower if you lose control.

When is it Too Cold to Cut Your Grass?

Even without freezing temperatures, it’s recommended that you stop mowing for the season once temperatures fall below 40°F (4.5°C) for at least a week.

Temperatures that low will send your grass into dormancy until the next spring, so even if there’s no frost, the grass simply won’t grow enough to justify cutting it.

Certainly, once things get cold enough for snow or daily frost, it’s time to put your mower away for the winter.

Can You Mow Grass Before a Freeze?

You can mow grass several days before an anticipated freeze. That way, the plants will have a chance to recover from the stress of being cut before the shock of being frozen. Mowing the day before a hard frost can damage the grass, and it won’t have a chance to recover before dormancy.

Can You Mow Grass After a Freeze?

If there’s an unusually early freeze in your area, you may still be able to get your lawn properly ready for winter, but don’t rush things. If temperatures start to move back up for a few weeks, you will have an opportunity to get this important fall task done.

Wait until the air temperatures stay above 40°F (4.5°C) for a few days, and those temperatures are expected to last for several more days. When you do decide to cut, mow late in the day when the grass has completely dried. Wet grass tends to get torn or bruised when cut, which can cause serious damage to the plants, especially with freezing weather in the not-too-distant future.

Is it Better to Mow Grass Before or After a Freeze?

Mowing in the Fall and the Beginning of Winter Tips

The best time to mow grass is several days before a freeze, and then leaving it alone until spring. That way, the grass has some time to recover before the arrival of potentially damaging weather.

Mowing your lawn after a freeze is more problematic. Cutting it when the blades have been damaged from being frozen won’t give the roots enough time to repair them before the winter cold sets in.

You should time your last mowing of the season carefully to protect your lawn from winter damage. Keep an eye on the weather forecast, and aim to do your last mowing at least a few days before the first anticipated hard frost.

Leaving the grass too long can encourage the growth of snow mold and harbour animal pests such as voles. While you should go into the winter with grass about 2 in (5 cm) tall, don’t lop off too much all at once, as that can send your grass plants into shock. Instead, for the last few cuts of the season, lower the blade height by no more than half an inch per mowing until you reach the desired height. Read everything aboout mowing height in my “How Short to Cut Grass Before Winter?” article here. 

You will probably have fallen leaves to deal with as well. If you have a mulching mower, it’s helpful to leave some of the mulched leaves on the lawn to provide some extra nutrients for your grass. However, never let intact leaves lie on the lawn all winter, as they can smother the grass.

Finally, before the first freeze, after your last mowing, apply fertilizer to the lawn. This will nourish the roots through the winter and get your lawn off to a good start next spring.

Mowing in Early Spring and Late Winter Tips

Do not be in too much of a rush to start mowing in the spring, as getting out on your lawn too early can cause damage until things dry out.

However, there are a few lawn care tasks to keep you busy before you bring out your mower for the season.

Start by clearing up any twigs or other debris that have accumulated over the winter, and then give the lawn a good raking to clear out any dead grass, as well as fallen leaves that you missed in your fall clean-up.

Then, aerate your lawn if the soil has become compacted. For small areas you can use a hand-held aerator, but for larger expanses you may choose to rent a larger machine to speed up the process.

Apply the first fertilizer of the year, and overseed any spots where the grass has died over the winter. Keep it watered if there’s not enough rain. Read our guide “Can You Plant Grass Seed in the Winter?” for more information. 

Finally, once the grass has started to put on some height, you can bring out your mower for the first cut.

Just like in the fall, wait until temperatures are reliably above 40°F (4.5°C). If you cut your grass short before winter, that won’t be an issue anyway, as it won’t be long enough to cut until temperatures are higher. Of course, do not cut when the blades are frosted, for the same reasons as in the fall.

It’s best to mow in the early evening when the grass has dried from the morning dew.

The first cut of the season should be around 2 to 2.5 in (5 to 6.5 cm), so wait until it’s about 3 to 3.75 in (7.5 to 9.5 cm) high before cutting it. Never cut more than 1/3 of the total height at a time to reduce stress on the grass plants. 

Mowing in Warm Winters vs Cold Winters (Location Matters)

Of course, all of the above advice pertains specifically to regions that regularly experience freezing temperatures in winter. That’s not the case in the southern United States, but even there, mowing practices will change in the winter.

In regions where it rarely freezes, and summer temperatures often soar close to or over 100°F (38°C), the grasses used for lawns are warm-season species such as Zoysia, St Augustine, or Bermuda grass. As things get somewhat cooler in the fall and winter, those grasses become dormant, so they do not need to be mowed, or certainly not as often.

Even if these grasses stay green, their rate of growth slows considerably, so you will not have to mow as frequently during the winter. You will probably have to mow every 2 to 4 weeks through the cooler months.

You should also keep the grass longer at this time of the year: depending on the species, anywhere from 2.5 to 5 in (6.3 to 12.5 cm).

If you choose to overseed your warm-season lawn with a cool-season grass such as annual rye grass, it will grow more vigorously and require more frequent mowing. Keep it short, at around 1 to 1.5 in (2.5 to 4 cm) so that it will die off faster in the spring when the warm-season grasses emerge from dormancy.

Do not fertilize your lawn at all during the winter months, and cut back your watering schedule to every 2 weeks.

Final Thoughts

As winter approaches and temperatures drop, the best thing that you can do for your lawn is leave it alone. Once you’ve given it its final fall cut, cleared off the fallen leaves, and applied the last fertilizer for the year, it’s time to give it a well-earned rest until spring.

In fact, mowing your lawn after freezing temperatures have arrived, or even walking on it when icy or snow-covered, can cause substantial damage to the grass plants and lead to a lot more turf repair when spring arrives!