Jack Frost Trails in Lawns

Wondering why you are seeing tiger or zebra stripes in your lawn? It is only temporary and nothing to be alarmed about.

Those weird patterns are not a sign of damage by disease or pests. It is only Jack Frost leaving his mark! In just a few days they will be gone. You will see no more signs of them when your whole lawn is dormant and when the grass greens back up next spring you'll never know those tiger stripes were there.

TifTuf Mooresville frost tiger stripes 1
Frosty fall nights can bring crazy patterns to warm season lawns like this TifTuf Bermuda. Photo by Hunter Patterson, Super-Sod Outside Sales in North Carolina.

Fall and First Frost

Fall is a time of transitions. As temperatures start to cool and the hours of daylight diminish, we see the seasonal changes in our yards. The trees put on a colorful show and leaves fall from the trees (make sure to rake them off your grass).

The luscious green of warm season lawns starts to fade (that's bermuda, zoysia, and centipede). In autumn, our warm season lawns begin the transition phase of going dormant (partially green and tan) and then turn tan-colored (light brown). The tan color of dormancy is ushered in quickly by first frost.

Jack Frost Trails

Sometimes the first cold night of fall brings a surprise!

Have you seen the interesting "trail" effects of Jack Frost on your lawn or in your neighborhood? If the conditions are just right, the frost will leave the most unusual zebra or tiger stripe patterns. It happens at our farms too!

TifTuf Mooresville frost tiger stripes 2
Notice here the strip of grass below the sidewalk is still green, but on the other side the frost has caused strange patterns of green and tan. Photo by Hunter Patterson.

What Causes These Patterns?

Warm season grasses are sensitive to freezing temperatures. In fall, there is an “in between” phase where the ground is still warm, yet the air has a rapid decrease in temperature. With the warm earth below and cool air above, there are different temperatures within the leaf blade canopy of your lawn, and air moves around through the blades.

Jack Frost trails happen if all these conditions are just right: grass height and density, warm ground temperatures, cold air (but not too cold), moisture content in the air and soil, and thermal air movement. Combined just right these factors and the thermal currents they create mean that some parts of the lawn get frost effect and turn brown while other parts stay just warm enough to avoid frost damage and stay green.

That is why you might get tiger stripes, but your next door neighbor doesn't. Or you could even see the effect in one part of your yard and not another. If first frost is later in the season and the ground is colder, then the frost trails won't happen because the whole lawn will go dormant.

You won't see the squiggly lines of Jack Frost Trails every year, but it is quite a strange phenomenon when it does happen. Just rest assured that it is a very short-lived effect caused by weather and is nothing to worry about.

So stay warm and cozy, safe and sound because summer will be back with green grass all around.

Laurinburg farm frost tiger stripes 2021 1-PocketsThese jack frost trails appeared in a field of TifTuf Bermuda at our farm in Laurinburg, NC. Photo by Micheal Buckner, Super-Sod Farm Manager.