Here's When You Should Stop Fertilizing Warm-Season Grass (& How To Prep For Fall)

Warm-season grasses get their name for good reason — they thrive in strong sun and temperatures between 75 and 90 degrees. If you live in the southern United States, you probably appreciate how lush and green your warm-season lawn looks in spring and summer. However, while these types of grass thrive in the heat, they still require diligent care to remain healthy, including mowing to the right height, consistent watering, and regular fertilization during their active growing season. Figuring out when to fertilize your lawn is key, though, as you don't want to continue adding nutrients when the grass's growth starts to slow. You should stop fertilizing a warm-season lawn by September to prepare the grass for fall.

The most common warm-season grasses include Bermudagrass (Cynodon dactylon), zoysiagrass (Zoysia spp.), centipede (Eremochloa ophiuroides), bahiagrass (Paspalum notatum), and St. Augustine (Stenotaphrum secundatum). They do best in full sun, tolerate dry weather, and grow well in clay-based and sandy soils. Deciding which fertilizer is best for your lawn can be difficult, but nitrogen-rich fertilizer helps most warm-season grasses grow in spring and summer. It can spell big trouble for your lawn if applied in fall, though, which is why your final application should come in late summer.

Fertilizing warm-season grass one final time before winter arrives is crucial to ensuring it has sufficient energy stored for the cold weather. It is generally recommended that you fertilize a warm-season lawn for the last time approximately six to eight weeks before your area's first frost, which means that most homeowners should do their final application by the end of August.

While fertilizing your grass too late may not seem like a big deal, it can cause major issues for your lawn. Warm-season grasses go dormant in winter, so their growth begins to slow as fall approaches. If you fertilize your lawn in September, it can delay this slowdown. Instead of allowing the grass to prepare for winter dormancy, fertilizing this late will encourage vulnerable new growth that isn't prepared for the colder temperatures and frost that come with fall. Your lawn may suffer injuries from the cold as a result, and the excess nitrogen may even lead to Spring Dead Spot, a fungal disease that affects bermudagrass.

In addition to fertilizing your lawn one last time to ready it for cooler temperatures, you'll need to take a few other steps to prepare warm-season grass for fall. Start by lowering your lawnmower's blade. While the recommended mowing height for warm-season grasses, such as Bermuda, zoysia, and centipedegrass, is 1 to 2 inches, many homeowners raise their blades by as much as 1/2 inch during the height of summer heat to help the grass retain moisture. Returning to the standard, shorter mowing height for warm-season grasses helps prevent diseases like snow mold in cooler weather.

One of the mistakes that everyone makes when watering their lawn is overwatering it. It's especially important to cut down on how often you water warm-season grass as fall approaches. As the weather becomes wetter, you don't need to irrigate your lawn as frequently as you do in the middle of a dry summer. However, you don't want the grass dehydrated and stressed, so give it 1 inch of water in two applications during weeks when it doesn't rain.

September is also the ideal time to apply a pre-emergent herbicide to your lawn if you've had trouble with weeds. When evening temperatures drop below 60 degrees, the soil becomes cool enough for winter weed seeds to germinate, but a pre-emergent formula can kill them before they have a chance.