Winterizing Lawns Not Good Idea

Visit the garden center at one of the “big box” retail outlets this time of year, and you will see fertilizer for winterizing your lawn. But experts with the Alabama Cooperative Extension System say winterizing is a bad idea for most of the lawns in the state.

Dr. David Han, an Extension turf specialist, says these winterizing fertilizer formulations are not recommended for the majority of Alabama lawns.

“Winterizer is not for bermuda, centipede, zoysia, and St. Augustine grasses,” says Han. “These are all warm-season grasses. The practice of winterizing lawns is strictly for cool-season grasses such as those found in lawns from North Alabama northward.”

Fescues and bluegrasses grow in cool weather and remain green through the winter. Han says that in the Deep South, these perennial, cool-season grasses rarely survive the hot summers but they thrive in the cool summers of New England and the Uupper Midwest. To maintain these grasses through the harsh winters of those areas, fall fertilization or winterizing is definitely recommended.

Attempting to winterize a warm-season grass with fall fertilization may actually harm the grass.

“These grasses go dormant or semi-dormant during winter. They produce very little if any growth from October through April in central Alabama. A fall application of nitrogen may actually stimulate them into producing succulent growth, which will only set the grass up for severe damage when a frost or freeze does occur.”

Dr. Charles Mitchell, an Extension soil scientist, agrees with Han.

“Auburn University’s Soil Testing Lab recommendations for these grasses state clearly that nitrogen should be applied up to September and no later,” says Mitchell. “Later applications are risky.”

He says that adding phosphorus or potassium to warm-season grasses in the fall is a wasted effort.

“Growth is slowing down dramatically. Root reserves are already established for next spring’s growth. A warm-season lawn establishes a healthy root system during the summer growing season. Adding more nutrients in the fall won’t make the grass healthier.”

Han and Mitchell both note there are exceptions to every rule. They say that some lawns in north Alabama that are planted in cool-season grasses may be that exception.

Han says because fescue, bluegrass, bentgrass and overseeded ryegrass grow rapidly during the cool days of autumn, these grasses can benefit from a fall fertilizer containing nitrogen.

Mitchell adds the Auburn University Soil Testing Laboratory recommends a fall nitrogen application for these grasses.

“The phosphorous and potassium in the fertilizer may or may not be needed by the fescue, but it won’t hurt anything,” says Mitchell. “Our winters are generally not cold enough to harm cool-season grasses so applying the phosphorus and potassium in the fall is not as critical as it would be farther north.”

Posted by lawremc at October 14, 2008 08:49 AM | TrackBack