Renovating Cool-Season Lawns
As cool fall breezes sweep across the state, now is a perfect time to breathe new life into an existing cool-season lawn. A primary cause for renovation is filling in areas where grass has died out. This could be symptomatic of poor pH, incorrect fertilization, excessive thatch, or a variety of other causes.
Make sure to start with a soil test and use the results to determine how much fertilizer and lime to apply to correct pH and nutrition. After the soil sample, reduce weed competition in the areas you plan to reseed. Plan to use a combination of hand-weeding and herbicides to tackle these weeds, especially tough perennials. If the area has thatch buildup, wait a week after applying herbicides before de-thatching.
For bare spots, till the top 4 to 6 inches and smooth the soil before re-seeding. Ensure uniform broadcasting by passing over the area in one direction with half of the seeding rate then applying the remaining half at a right angle to the first pass. For areas where grass is thin but present, use a de-thatcher or verticutter to slice an opening in the ground. Drop seed into these furrows and lightly cover. Some cool-season grasses, such as tall fescue, do not spread to fill in an area but will form bunches.
Keep newly planted areas moist with light irrigation. As these areas fill in, encourage deeper rooting by watering less frequently but for a longer duration. Deeper roots are more resilient and can lead to a healthier stand of grass that has fewer weeds and disease issues.
Avoid over-fertilizing or adding too much nitrogen as this can push growth too quickly, leading to stress and health issues. For information on when to re-seed, fertilize, and manage weeds in different lawns, see the NC State Lawn Maintenance Calendars for each type of turf in the “Lawns” chapter of the NC Extension Gardener Handbook.
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