Search
If you search the internet for fall lawn care tips, you’ll quickly find lists recommending practices such as aeration, dethatching, fertilizing, seeding and adjusting mowing height. While those recommendations may be appropriate for cool-season lawns in northern states, they do not always translate well to warm-season turfgrasses grown in south Louisiana. Common lawn grasses in our region — St. Augustinegrass, centipedegrass, bermudagrass and zoysia — are preparing for winter during the fall, not entering a period of vigorous growth.
Before following generic lawn care advice, it is important to understand how each practice fits into the seasonal growth cycle of warm-season grasses.
Annual bluegrass, a prolific seed producer and troublesome winter weed, is best prevented with fall preemergence herbicide applications. Photo by Eric DeBoer
Aeration, or aerifying, involves removing small cores of soil from the lawn to relieve compaction and improve air and water movement into the root zone. While aeration is a beneficial practice, fall is generally not the best time to perform it on warm-season turf.
As temperatures cool and days shorten, warm-season grasses begin slowing their growth and storing energy for winter survival. Aeration creates injury to the turf that requires active growth for recovery. For this reason, core aeration is typically best performed in late spring or early summer when the grass is actively growing and can quickly repair itself.
Fall takeaway: Skip major aeration projects in the fall and plan them for next growing season.
Thatch is a layer of living and dead stems, roots and shoots that accumulates between the soil surface and the green turf canopy. Excessive thatch can interfere with water infiltration, nutrient movement and root development. However, a small amount of thatch is not necessarily a problem and can help moderate soil moisture and temperature fluctuations.
Removing thatch through verticutting, scarifying or vertical mowing can be highly disruptive to the lawn. Like aeration, these practices are best performed during periods of active growth so the turf can recover quickly. Conducting aggressive thatch removal in the fall may leave the lawn weakened heading into winter.
Fall takeaway: Evaluate thatch levels now but save aggressive removal practices for late spring or summer.
Fall fertilization can be one of the most misunderstood lawn care topics in Louisiana. Many winterizer fertilizers promoted nationally contain nitrogen and potassium. While potassium may benefit lawns with a documented deficiency, more potassium is not always better.
The best way to determine whether potassium is needed is through a soil test. Applying potassium to soils that already contain sufficient levels is unlikely to provide meaningful benefits.
Nitrogen deserves even more consideration. In general, nitrogen applications to warm-season lawns should be limited as the growing season winds down. Excess nitrogen late in the year can stimulate tender growth when the lawn should be preparing for dormancy.
If your goal is maintaining color during the fall months, foliar iron applications can often provide greening without encouraging excessive growth.
Fall takeaway: Soil test before applying potassium and avoid heavy nitrogen applications late in the season.
Fall seeding is commonly recommended for cool-season grasses because cooler temperatures favor their establishment. Warm-season turfgrasses operate differently.
The cooler temperatures and shorter days of fall slow germination, establishment and growth of warm-season species. Newly established seedlings may not have enough time to develop before winter arrives. While fall seeding is not impossible, the odds of success decline significantly as temperatures cool.
Fall takeaway: Wait until late spring for most warm-season turf seeding projects.
A common recommendation found online is to lower mowing heights in the fall. This advice is often intended for cool-season lawns and does not necessarily apply to warm-season grasses in Louisiana.
For warm-season turf, continue mowing at the recommended height for your species throughout the fall. Avoid removing excessive leaf tissue in an attempt to winterize the lawn. Maintaining proper mowing height helps preserve turf health and supports continued photosynthesis as long as the grass remains active.
As growth slows, mowing frequency can gradually be reduced, but the target mowing height should remain the same.
Fall takeaway: Keep mowing at the recommended height and simply mow less often as growth slows.
One fall lawn care task that is often overlooked in Louisiana is leaf management. Leaves that accumulate on the lawn can block sunlight, trap moisture, and create favorable conditions for disease development.
Rather than allowing leaves to build up, remove them regularly with a mower, rake, or blower. In many cases, dry leaves can be mulched into the lawn in small amounts without causing problems.
Fall takeaway: Keep excessive leaf accumulations off the lawn throughout the fall and winter.
Fall is an excellent time to think about winter weed control. Many troublesome weeds such as annual bluegrass (Poa annua L.), lawn burweed (Soliva sessilis Ruiz and Pavon), henbit (Lamium amplexicaule L.) and chickweed (Stellaria media [L.] Vill.) germinate as temperatures cool.
Preemergence herbicides applied in early fall can help prevent many winter annual weeds from becoming established. Be sure to select products labeled for your turfgrass species and follow all label directions.
Fall takeaway: Fall is often the most important time of year for preventing winter weeds.
Not all fall lawn care advice is created equal. Many recommendations found online are written for cool-season lawns growing hundreds of miles from Louisiana. For warm-season grasses, fall should be viewed as a time to prepare the lawn for winter rather than aggressively renovate it. Focus on proper mowing, leaf management, soil testing and winter weed prevention, while saving disruptive practices such as aeration, dethatching and major seeding projects for the growing season.
