One thing that is often confusing is “winterizing” the lawn. Fertilizers with winterizers contain nitrogen, phosphorus and potassium, like other complete fertilizers. The premise behind applying these fertilizers is to promote healthy roots and good health before winter weather arrives. However, one thing you may not realize is that these fertilizers are not recommended for Alabama’s warm-season grasses, the most common off whichare zoysiagrass, centipedegrass, Bermudagrass and St. Augustinegrass. Winterizing fertilizers are for cool season grasses. Cool season grasses are usually grown in lawns from North Alabama northward. Grasses such as blugrass and fescue do not survive Alabama summers , but when grown as a cool season lawn, winterizing is necessary.
Using winterizing fertilizers on warm-season grasses is risky. Fertilizers are not recommended past September 1st and earlier for North Alabama. These turfgrasses do actively grow much from October until April. They will be fading into winter dormancy soon. Applying nitrogen fertilizers in the fall will encourage new, tender green growth. Should a frost or freeze occur, it could damage the grass, and freeze damage is hard to bounce back from. Other winterizing fertilizers may contain mostly potassium (potash). Warm-season turfgrasses in soils with adequate potassium are able to withstand cold weather somewhat better. Adding any fertilizer, even potassium, to lawns is not advisable without a soil test.
Just because we may not want to use fertilizers in the fall on our warm season grasses does not mean we shouldn’t winterize them. Now is a great time to survey your lawn for weeds and insects. Fall armyworms are doing a number on bermudagrass lawns across the state right now. The best line of defense is your eyes. Check the edges of damaged areas in your lawn for signs of armyworms. Luckily, the fall armyworms consume the foliage, but do not kill the roots of the grass.
White grubs may also be a problem. Unlike the fall armyworms, they do a lot of harm to the roots of lawn grasses. Summertime is actually a better time to control the grubs. The grubs and the damage are noticed more now because the damage is more evident and the grubs, of course, are larger. But larger grubs are harder to control with insecticides. If you see them now, you will have them in the spring — through the winter, the grubs will hunker down a little deeper in the soil.
Weed pressure in our warm-season lawngrasses is year round. In late winter we notice mature cool-season weeds in the lawn and a lot of them can be prevented by applying herbicides before they germinate. Pre-emergence treatments are applied about two weeks before weeds germinate; late September and October are usually good times to apply to warm-season grasses. Be sure to correctly identify the weed and the type of turf you have, and always follow label directions — not all herbicides are labeled for all turfgrasses. Post-emergent herbicides can also be applied in the fall for weeds that already exist.
Herbicides are not always the answer. Healthy lawns are much more resilient to weed pressures than unhealthy lawns. For most grasses, this means having correct mowing height, fertilization and sunshine. Home lawns that are not healthy will have weeds and herbicides may only slow them down.