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How to Help Warm Season Grass in Super Cold Weather

Give your Southern lawn the best chance at fighting off winterkill.

To protect themselves from unfavorable temps, Bermudagrass, Zoysia, St. Augustine, and other warm-season grass types naturally go dormant for winter, and the first frost is usually no big deal—it's nature's clue the time has come. However, if one chilly night turns into several days of super-cold weather, winterkill can happen (it's all in the name) and your lawn may need help rebooting once spring rolls around.

Here's what to know and how to handle it if freezing temps swoop in and send your lawn into a wintry spiral.

What Is Winterkill, Anyway?

Before we get into winterkill, you should know about psychedelic grass. No, it's not an obscure cash crop. It's the tie-dye-like pattern of brown-and-green grass that can appear on your lawn after the first frost. It's normal. Your turf is just starting to go dormant in different spots at different times. The good news is, it's also a good indicator that, come warmer weather, your grass will perk right back up with your spring lawn care routine.

Winterkill, on the other hand, is what can happen when prolonged cold weather joins that first frost in the South. Warm-season grass needs time to acclimate to the cold, so if it's suddenly freezing and stays that way, the blades' protective crown tissue could end up damaged, causing your grass to die over the winter.

Can I Protect a Southern Lawn from Winterkill?

You can't control the weather, but you can help your lawn endure it. The key here is knowing the average first-frost date for your area, so you can get prepared before winter's wilder elements come knocking. Here are some tips for increasing your lawn's chance of survival. 

Be Smart About Mowing

  • Mow higher. Gradually raise the mowing height over the last few weeks of fall to help insulate your lawn before the first expected frost.
  • Then, stop mowing. The first frost signals it's time for your grass to stop growing, which means the mowing season has come to an end for you, too.
  • Don't walk on your grass. Another reason to stop mowing is to minimize any activity happening on your lawn if fall weather is feeling a lot like winter.

Be Even Smarter about Feeding

  • Feed your lawn on schedule. You want to apply your fall fertilizer at least one month before the first expected frost for your area, so don't wait until the last minute.
  • Cut back on nitrogen in fall. Sounds scientific, but nitrogen is the ingredient chiefly responsible for encouraging growth. Remember, you're trying to put your lawn to sleep!
  • Increase potassium in fall. Use a fertilizer packed with potassium, a winter-hardening nutrient that will help your turf stand up to cold temperatures. When applied to Southern lawns in early fall, Scotts® Turf Builder® WinterGuard® Fall Lawn Food does just the trick. Follow the label directions and you'll help build strong roots and a hardier lawn.

Will My Southern Lawn Recover from Winterkill?

The frustrating part for any lawn geek is that you can't really know if winterkill happened until spring temps return. Rest assured, though, that most warm-season grasses will recover from polar conditions with a little help—especially if they've been well-cared-for leading up to this point. Here's what to do if your lawn doesn't green up once warm weather emerges.

  • Wait to fertilize. Make sure warm weather is here to stay before jump-starting a spring feeding. Applying fertilizer invites new growth, and you don't want a sudden icy morning to damage tender grass blades.
  • Let light in. If your yard has become shady from ample tree growth, trim some limbs to let more light come through. Sunshine warms up the soil during the day, which helps it tolerate cold nights.
  • Overseed bare patches. If there are dead spots in your lawn after winter, spread a thin layer of grass seed to help fill those back in. Check out our steps for overseeding your lawn for more tips and tricks.
  • Dethatch your lawn. Reducing the layer of dead grass in your lawn (AKA, dethatching) will help raise the ground temp and let air flow through. Learn more about how to dethatch your lawn in our DIY guide.

They say there's no such thing as bad weather, just a lack of preparation for it. A surprise stint of freezing temps may seem like an exception, but with these handy tips, you've got your Southern lawn covered no matter what winter brings with it.