Winter kill (or winterkill) with regards to lawn, refers to any severe damage or death sustained by the turf during the winter months. For the most part, well cared for turf is resilient and strong, but winter weather can be unforgiving to even the best lawns. Winter kill can occur under a variety of conditions.
- Ice cover - periods of snow followed by warm temperatures, then freezing temperatures, can create a thick layer of ice on a lawn. Most cool season grasses can handle these conditions but if ice persists for more than 30 days damaged or killed turf can result.
- Snow cover - a persistent snow cover can create warmer, insulated conditions near the soil surface. Gray or pink snow mold may break out in these conditions. Mouse activity may also occur and leave noticeable trails in the grass in the spring.
- Bare dormant grass - can become dessicated or dried out when exposed to winter winds and extreme temperatures over long periods of time. Foot traffic over bare dormant grass is less desirable than snow cover.
Ice, wind, and scalping can inflict the most serious damage by injuring the sensitive crown of the plant. Extreme temperatures, wind, and freeze/thaw conditions can inflict the worst damage. If winterkill occurs from these conditions, recovery may take longer than expected.
Winters can often be unpredictable and may put your lawn through any or all of these conditions during the course of a winter. The best thing to do is make sure the grass has hardened off, you've "put the lawn to bed" properly, monitor the weather, and deal with conditions as they occur.
Should you get out there with an ice chipper in the middle of January and chip away four inches of ice off your lawn? Normally I wouldn't recommend it, but if you have a lawn that is a showpiece, you may want to take it that far. However, a lawn managed on a sound lawn care program should be able to recover from most of what winter can put it through.