Winterkill and Lawn Care
You might think of winterkill as a something that only happens in warmer climates, but it can happen everywhere. The constant in winterkill for southern lawns versus northern lawns is that stressed lawns everywhere are more likely to be affected by winterkill. Healthy grass during the summer has a much better chance of avoiding winterkill in the winter. Here are some tips for avoiding winterkill and for helping your lawn recover from winterkill.
Eliminate Thatch Buildup
Thatch isn't just a cosmetic issue. While thatch (an area of dead stems between the roots/soil and the green, growing tops of the grass plants) is an area where fungi, bacteria, and insects can lurk, it causes other problems in the lawn, as well. When thatch buildup elevates the growing points of grass plants up away from the soil, it makes the plants more susceptible to colder temperatures. Plants that root in the thatch layer as opposed to rooting in the soil are not as drought-tolerant or as prepared for cold weather.
Use a power thatch rake to eliminate thatch. You can also aerate the lawn and rake finely sifted compost into the aeration holes.
Avoiding Winterkill in the South
Southern lawns and northern lawns are on different schedules. That means that proper care in order to avoid problems happens at different times. In addition to staying on top of thatch buildup, and ensuring healthy lawn care throughout the year, there are a couple of other things to watch out for to keep the lawn healthy and avoid winter kill.
First, stop fertilizing with Nitrogen after August. Fertilizing any later than that can interfere with the plants going dormant. If the grass doesn't go dormant on time, it will not be "hardened off" in time for winter and can be damaged by cold and windy weather.
Second, make sure to cut the grass regularly until it is dormant. This keeps the growing part of the grass stem low and near the soil, less exposed to colder air and wind.
Avoiding Winterkill in the North
Lawns in colder areas can develop winterkill that isn't obvious until the grass starts growing vigorously again in the spring. The key to avoiding winterkill in the north is to make sure that you keep mowing the grass as long as it is actively growing. Cool-weather grass will grow later into the season than warm-season grass. Keep the growing point of the plants as close to the soil as possible. Follow good grass care tips during the summer.
If you notice problems with winterkill in the spring, the lawn will benefit from a spring fertilizing. (Otherwise spring fertilizing isn't necessary.) Wait until the soil has thawed and the soil temperatures are at least 55 degrees before fertilizing.
If your lawn anywhere experiences winterkill, as long as you take care of it the following summer, and as long as the winterkill patches are not large, the lawn will fill in fairly quickly on its own when the grass is actively growing.