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How to minimize winter cold damage to lawns
December 12, 2008
CORVALLIS, Ore. – Lawns can take a beating in the winter both east and west of the Oregon Cascades, and strategies to minimize cold damage vary from region to region.
"The grass in western Oregon never really develops a cold tolerance as it does east of the Cascades," according to Tom Cook, retired turf grass specialist with the Oregon State University Extension Service.
"On the west side, when Arctic fronts bring frost, grass injury is normally limited to leaf damage, which might look brown or yellow when warm weather returns.
"But," Cook added, “lawns will usually recover in a few weeks.”
Damage can be more severe if turf receives concentrated foot traffic while frozen. Grass plants can be killed, leaving dead spots in the spring. Cook recommends keeping off the lawn, especially if it is frozen. In western Oregon, the soil usually is saturated through the winter and is especially prone to compaction, making growth difficult in the spring.
East of the Cascades in central and eastern Oregon, grasses generally go dormant in the winter and are tolerant of cold.
"As days get shorter and night and day temperatures drop, grass growth slows down,” Cook said. Eastern Oregon generally gets lots of sunshine during the day, and grass produces sugars via photosynthesis. As sugars accumulate, water in grass crowns and rhizomes decreases. An increase of sugars and decrease of water in grass tissues allows plants to tolerate cold."
Continued, increasing cold kills the older grass leaves, and eastside lawns turn brown. They are ready to grow again when temperatures warm in the spring, Cook said.
Cold damage in lawns is worst in windy areas of central Oregon and the Columbia Gorge.
"Desiccation, or death by moisture loss, often occurs as grass tissue loses moisture it can't replace because roots are frozen in the soil and can't take up water," he explained. Areas most likely to be damaged often are at the crest of a rise, on top of mounds or on slopes exposed to the wind."
Cook recommends these strategies to help minimize cold injury in lawns:
Avoid applying excess fertilizer in late summer and early fall. Lawns that are pushed hard with nitrogen tend to remain succulent as they begin the normal hardening-off period, thereby reducing cold tolerance. Apply no more than two pounds nitrogen per 1,000 square feet near mid-November. Late fall fertilizing stimulates early spring color and reduces the need for mid-spring nitrogen applications.
Continue mowing as long as the grass keeps growing.
Remove tree leaves from lawns; they smother turf and foster snow mold growth.
On the east side of the mountains, make sure lawns are adequately watered as fall approaches. This will decrease the likelihood of winter desiccation injury.
Source: Tom Cook