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What Temperature Does Bermuda Grass Go Dormant?

What Temperature Does Bermuda Grass Go Dormant?

In the fall, if your area of the country gets cool enough, your lush Bermuda lawn will start to brown and enter dormancy for the winter. This happens when daytime temperatures reach the mid-60s and below. Although the grass won’t start turning brown right away, dormancy is triggered by shorter daylight hours, cooler temps, and overnight frosts.

There are things you can do in late summer and early fall to prepare your Bermuda grass to weather the winter and revive strong in spring.

Why Does Bermuda Go Dormant?

Bermuda grass is a warm-season grass that is listed as a USDA zone 7-10 plant. If you’re in cooler regions, you can choose Bermuda as a summertime grass that will keep your yard green when cool-season grasses are dormant.

Cool temperatures trigger dormancy in warm-season grasses when the daytime temperatures drop below 65, and nighttime temperatures are cold enough for frost to develop on the grass. In early fall, the daytime temps will melt the frost and warm the grass, but it will already have started storing energy and using less to feed its blades. This also is encouraged by the decreasing daylight hours in the late fall and winter, when the grass can’t photosynthesize as much for lack of sun.

Not only is the sun out for less time during the winter, it sits lower in the sky even during the day. This casts longer shadows of trees, houses, and fences over the yard. Those areas in the shade will be the first to fade. The lower the temperatures and light levels get, the more frost will develop overnight. Bermuda grass isn’t made for frost, so it will brown quickly once fall settles in, and the soil temperature is regularly around or below 65.

What Happens When Bermuda Grass Goes Dormant?

What Happens When Bermuda Grass Goes Dormant

Before and as the blades die off, the roots of the grass will store energy from photosynthesis production and nutrients absorbed from the soil. Triggered by the temperature change early in the fall, this is a slow process that happens over several weeks.

How To Tell If Bermuda Grass Is Dormant

Being able to tell if your Bermuda grass is fully dormant will help you coordinate the lawn’s maintenance schedule with the grass’ natural cycle. The grass will brown from the tops of the blade downwards, so examine whole blades up close and not at a glance from above, as this might only show the upper half that has wilted while blades may still maintain a green lower half. There may also be fully intact blades under taller ones that are providing insulation.

When Should I Winterize My Bermuda Grass?

Some aspects of winter lawn care shouldn’t be done until the grass is fully dormant and the blades are dead, including applying herbicides, fungicides, or pesticides. However, other aspects of winter prep begin in the late summer and early fall, including fertilizing less, stopping mowing, and overseeding with a cool-season grass if you want to.

Late Summer

While temperatures are still warm and frost is a month or two away, you should start fertilizing the lawn less. Using fertilizers with less nitrogen will support root growth and energy storage without directing energy towards blade growth. You should also slow down, or stop, mowing at this time and allow your Bermudagrass to grow up to 3 inches, which will provide some insulation over the winter.

Early Fall

5 to 6 weeks before the first frost is when you would overseed your lawn with a cool-season grass. For your Bermuda lawn, rye is the best choice because it won’t compete with the Bermuda in late spring and early summer; it will have gone dormant when the Bermuda revives. Other grasses like fescue and Kentucky Bluegrass stay longer into the warm months and might interfere with Bermuda regrowth.

Early Winter

If you don’t plant a cool-season grass over winter, you can take this opportunity to apply herbicides for any green weeds that are showing up, and that might crowd out some of the grass in spring. Putting down a Bermuda-safe pre-emergent herbicide will target all non-Bermuda winter growth, and spot-treating living weeds won’t affect the dormant Bermuda roots. Be sure to do this only once your Bermuda grass is fully dormant (any blades showing should be like straw at that point).

Attending to cool-season weeds when your Bermuda is dormant allows those weeds to absorb the herbicide through their living leaves when the Bermuda doesn’t have any. This same rule applies to fungicide and nematicides, which should also be applied while the grass is not actively absorbent.

Should You Water Dormant Bermuda Grass?

Should You Water Dormant Bermuda Grass

Even while it’s dormant, warm-season grass needs water during the winter. Luckily, if it snows or rains, it should get the one inch of water per dormant month that it needs to survive, and you won’t have to do anything. If the temperatures are freezing, you shouldn’t water the grass, so the soil doesn’t freeze. However, if temperatures are above freezing but cold enough for the grass to be dormant, you can water a little bit here and there over the month to provide it with the full inch.

Is It OK To Mow Dormant Bermuda Grass?

While the grass is dormant, it won’t be growing, so there isn’t much need to mow a Bermuda lawn during the winter. If you have a cool-season grass over it, you can mow, and it won’t hurt the dormant Bermuda root system. In the spring, however, Bermuda lawns like to be “scalped” or mowed very closely (down to an inch) for the first mow of the season to encourage strong regrowth. This should be done after the last frost of the spring.

Is it OK To Aerate Dormant Bermuda Grass?

You should avoid aerating Bermuda grass in the fall or winter while the grass is going into dormancy or while it’s dormant because it won’t be able to heal root damage. Dormant grass can’t use its stored energy to heal and maintain enough to revive in the spring. Any kind of winter damage to the roots can disrupt the grass’ ability to regrow.

At What Temperature Does Bermuda Grass Come Out Of Dormancy?

When temperatures reach a daily 65 degrees, and there is no more frost overnight, Bermuda grass will start to come out of dormancy.

How Long Does It Take Dormant Bermuda Grass To Turn Green?

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Your Bermuda lawn will start regaining its color and greening up as soon as it begins to sprout. It usually takes between 2 and 4 weeks for blades to begin covering the lawn again. Since a low-cut mowing is recommended at the beginning of the season, the ground will be exposed, and the longer, increasingly long, and bright days will encourage grass growth.

 Warm-season grass goes through 3 stages as it regrows in the spring:

  • Revival – The grass’ regrowth is triggered by warmth, light, and a lack of frost.
  • Emergence – The grass regrows over a few weeks as the roots awaken and can direct their stored energy to blade production.
  • Fully Regrown – After a few weeks of regrowth, you can mow your lawn again and enjoy the dense coverage over the warm months.