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Extension: Start now to prepare warm-season turfgrass for fall, winter
Grass
Jonas Weckschmied, Unsplash

Nature has recently given us a preview of cooler fall weather. While autumn is still a few weeks away, now is the time to begin preparing warm-season lawns for the fall and winter seasons. 

The proper care in late summer and early fall will help a Bermuda, centipede, or zoysia lawn enter dormancy at the appropriate time, protect against cold injury, prevent winter weeds, and reduce disease problems when the lawn greens-up next spring.


August

Make your last application of nitrogen. Nitrogen stimulates growth, but as the active growing season comes to an end in August for warm-season grasses, we want to allow growth to slow down in preparation for dormancy. 

Fertilizing in September can delay dormancy long enough for warm-season turfgrass to suffer from cold injury. Nitrogen in the fall also sets lawns up for Spring Dead Spot. 

It’s ok to make a final application of nitrogen in August, but as days get shorter and nights grow cooler, let warm-season turfgrasses go through the natural processes to enter dormancy, storing energy in the roots for a healthy spring green-up.

Adjust mowing height. The normal mowing height range for grass like Bermuda, centipede or zoysia is 1-2 inches. If you’ve been mowing on the lower side, raise the mower blade up to cut at the 2 inch height.

Continue irrigation. Warm-season lawns still need an inch of water per week as they slow growth for dormancy. 

If rainfall is sufficient, skip irrigation; overwatering encourages root rot and other turfgrass diseases. In weeks with no rain, irrigate twice weekly, applying half an inch of water with each session. 

Watering deeply and less frequently encourages roots to grow deeper into the soil.




September

Collect a soil sample for testing. Fall is an excellent time to apply lime and other amendments to improve the soil that nourishes turfgrass. Each species of warm-season turfgrass has a different optimal pH range.

 If soil pH is too low, dolomitic lime can be applied to raise it, but it’s a process that can take several months. A laboratory analysis is the only way to know how much of an amendment the soil needs to create the desired change from the measured starting point. 

Apply pre-emergence herbicide. If you’ve had lawn weeds in the past, chances are strong that you’ve got weed seeds in the soil, just waiting for the temperature and moisture conditions to be right for growth. 

A pre-emergence herbicide prevents seed germination so that weeds don’t get a chance to grow. 

That’s why it’s important to apply pre-emergence herbicides in September, before soil temperatures cool enough to allow winter weed seeds to germinate, or before nighttime temperatures drop below 60 degrees Fahrenheit. 

Pre-emergence herbicides contain various active ingredients and typically control several broadleaf annual weeds and some annual grass weeds.

 The products continue working in the soil for several weeks. Some products allow or recommend a second application 8-10 weeks after the initial treatment. 

While we don’t want to fertilize warm-season lawns after August, a pre-emergence herbicide that contains potassium as the carrier product will enhance winter hardiness in bermudagrass lawns. 

Look for pre-emergence herbicides that have 0-0-7 or something similar, with the first two numbers (for nitrogen and potassium) being zeros. Note that products containing atrazine should not be used on bermudagrass lawns.

When using herbicides and other pesticides, always follow the directions on the product label – including using specified personal protection equipment. 

Application rates are legal limits that define the minimum amount at which the product is effective and the maximum amount at which the product is safe to use for you, your plants, and the environment.

For more information on lawn care and soil testing, please visit the Forsyth County Extension website by clicking here. Call Forsyth County Extension at 770-887-2418 for soil sample payment and drop-off instructions.


UGA Extension strives to translate the science of life for use in everyday living. Forsyth County Extension is supported by the University of Georgia, Forsyth County Board of Commissioners, Forsyth County Board of Education, and United Way of Forsyth County.