What Temperature Does Grass Stop Growing?

As the bright colors of fall ebb into the icy grips of winter, the temperatures drop drastically. With this temperature drop, the plants around our homes, in our gardens, and across our lawns cease growing. But how cold does it need to get before the green expanse of the lawn stops growing altogether? Let’s find out. 

Does The Cold Stop Grass From Growing?

Like most plants, grass doesn’t grow much, if at all, during the winter months. For the most part, grass goes dormant altogether, especially if you live in an area that experiences harsh winters. Grass growing in places in the southern U.S. that don’t experience harsh winters or much of a temperature change might only achieve some degree of dormancy, if at all. 

However, for most folks in the mid-to-northern U.S., your lawn will stop growing altogether and go dormant to survive the icy temperatures of winter. 

What Happens To Grass During The Winter?

As the warm fall afternoons drop to the freezing temperatures of late fall and winter, you’ll probably notice a few things with your lawn. In many cases, the grass covering your yard will turn brown, taking on a dead appearance.

This happens due to the seasonal growth pattern of most grasses, which require several factors to grow and thrive. Sunlight and water are integral ingredients for proper photosynthesis, as the plant uses light energy to convert water and carbon dioxide into glucose. Glucose is an essential building block for growth, as it helps create cells and seeds. 

In addition to light energy, plants pull nutrients from the soil, air, and water to continue the process. These cycles continue throughout the year, guided by temperature changes from season to season. Temperature fluctuation is what tells the plant to do throughout the year, whether it accelerates or slows down specific processes. 

Dormant Grass

In warm weather, these temperatures allow plants to grow and reproduce. However, in cooler weather, the temperatures tell the plant its time to go dormant or die off. Since we don’t want to get overly technical, you can expect your grasses to slow their growth (or completely stop growing) during the winter, whereas they usually flourish in warmer weather. 

Aside from the scientific side of things, the type of grass you have plays a role in the exact growth patterns of your lawn. There are warm-season grasses and cool-season grasses, so the kind you have can impact how long your yard remains active and growing. 

For example, if you have cool-season grass, like Kentucky bluegrass, fescue, or ryegrass, you might notice your lawn accelerates its growth in the cooler temperatures of early spring and late fall. Of course, the lawn will still slow down and likely stop growing after the temperatures drop below a certain point. 

At What Temperature Does Grass Go Dormant?

The temperature (air and soil temperatures) at which grass goes dormant in the late fall hinges on your grass type. As the name implies, warm-season grasses don’t appreciate the cooler weather, so they tend to go dormant sooner than other varieties. Generally, warm-season grasses begin to go dormant when the temperature regularly dips below 65 degrees Fahrenheit. 

On the other hand, cool-season grasses tend to flourish in lower temperatures, so they last longer into the fall. The specific temperature threshold depends on the particular variety of grass, but most cool-season grasses continue to flourish in temperatures lower than 50 degrees Fahrenheit. Once the temperatures drop below 32 degrees Fahrenheit and frost regularly occurs, the grass will gradually stop sprouting altogether. 

What Temperatures Cause Grass To Stop Growing In The Summer?

Like the lower temperature threshold that causes grass to stop growing, there’s a higher end of the spectrum with a similar result. When the temperature climbs beyond a certain point, the grass may enter a dormant state to protect itself from drought, extreme heat, or other circumstances. 

Cool-season grasses are more susceptible to heat and tend to flourish in cooler temperatures. Conversely, warm-season grasses are more tolerant of high temperatures, as they don’t do as well in cooler temperatures. 

Generally, temperatures regularly exceeding 90 degrees Fahrenheit will send your lawn into a state of dormancy. The higher temperatures signal the root system, indicating it’s time to become dormant to protect the grass and ensure survival in unfavorable conditions. 

This is why you might notice your lawn becomes brownish or yellowed in the extreme heat of the summer, especially if it doesn’t receive enough water due to a drought. In intense heat and drought, many types of grass can maintain a dormant state for three to four weeks before it dies. That said, prolonged heat and drought can kill the grass over time. 

How Do I Prepare My Lawn For The Winter

Lawn With Frost and Snow

As winter creeps in, bringing its sub-freezing temperatures, it’s not a bad idea to prepare your lawn. Before the first frost takes hold of the area, mow your lawn a few times. Try to cut the grass a few times after the grass enters a dormant state but before frost becomes a problem. 

In an ideal setting, your grass should be about 2 ½ to 3 inches in height when the cold weather rolls in for its stay. You can also fertilize the grass one final time before the first hard frost, as this can help improve the condition of your lawn (it gives your yard a boost of nutrients to tide it over through the winter months). 

If your grass is already frozen, don’t cut it, as this can stress the grass and affect its ability to bounce back in the spring. So, if you notice your grass has stopped growing significantly each day, you may want to leave it alone until it “wakes” from its dormancy (usually when the weather springs from winter).