Fall is the best time to prepare your lawn for the coming winter, and give it a great boost for next spring. But where do you start? That can depend on where you live and what kind of grass is growing.
Cool season turfgrasses and warm turfgrasses each require their own special treatment. For those of us living in the South, 99.9% have warm season turf so that is what we will focus on in this blog.
Warm Season Grasses
In the southern states, the warm season species go dormant and yellow all winter. Warm-season turfgrasses such as Bermudagrass, Zoysia grass, St. Augustine and Centipede grass will go dormant after the first frost. Avoid fertilizing a warm season turfgrass in the autumn.
Get a Soil Test
If you have never taken a soil sample, do it now, in the fall. Assessing your soil health in the fall gives you time to correct nutrient deficiencies and pH problems before spring. If you have had a soil sample, fall is a good time to take another and see if you are making progress in moving the key numbers in the right direction. All of our lawn care customers receive a soil sample with their first visit and then we compare a new sample every other fall to see how we are progressing.
Once you get past early September (About the time football season starts) you should not need to fertilize your lawn with nitrogen-containing fertilizers. This is why ‘Winterizers’ and ‘Weed & Feeds’ are misleading and can ultimately cause damage to your lawn. Though you may not need nitrogen, most of our lawns need Potassium. With our sandy soils and excessive rainfall, potassium levels are usually low and Potassium plays a key role in winterizing your lawn by enhancing cold tolerance of turfgrass. Again, refer to your soil sample for a guide to how much you may need.
There are several varieties of turfgrass weeds affecting warm season turf. Those varieties can be broken down into summer weeds and winter weeds. They can also be broken down to broadleaf, grassy and sedges but for this discussion, we will keep it to primarily summer and winter weeds. The pests you are seeing in August and September are summer weeds. They are going to eventually die out as the soil temperature and air temperature drop, however, you should be applying a pre-emergent in August or September to help prevent the oncoming winter weeds. One of the worst winter weeds in the south is Poa annua. A timely application of a pre-emergent will help to keep this noxious weed from becoming a headache in your lawn this winter.
One might think that you will not need to water during the fall, as the temperatures drop and turf growth begins to slow. That would be a false assumption. Even when the lawn goes completely dormant, we still recommend watering your lawn once per week (if it hasn’t rained). This helps to keep the roots moist and keep your irrigation operating correctly. Keeping an irrigation system off for an extended period of time can cause the rubber parts in the heads to dry rot and cause leaks. Also, October is historically our driest month and daytime temps can still reach the 80s. We saw a significant amount of turf damage during the Fall of 2016 when it didn’t rain for over 70 days. Even homeowners with irrigation struggled to keep up with water requirements during that period.
Now that I mentioned irrigation and October being dry I should follow up with fungus. In the later months of fall, moving into winter (November & December) the temperatures are cool at night and warm during the day and if you add some rain to that mix you have a recipe for Brown Patch Fungus. Make sure to monitor your watering and be on the lookout for fungus if conditions are right. A rain sensor for your irrigation system is another tool that can help you from overwatering throughout the entire year.
Continue to mow grass until it stops actively growing. As you move through the fall and your grass starts slowing down, start lowing the height in which you cut the lawn (never remove more than 1/3 of the turf blade height at one time). The idea here is to remove more of the leaf blade that can potentially be damaged by any frost event. This is sometimes called winter kill. Also, a lower turf height will cause faster green up in the spring. For the final mowing of the season, cut warm-season grasses between 1½ and 2 inches, which is just a little shorter than you should cut it during the spring and early autumn.
Your lawn has been mowed, played, walked and some have even been driven on throughout the summer months. All of this activity causes compaction and by the time you get to fall it’s a great time to give your lawn a breather. We have tested over the past 2-3 years liquid aeration and prefer this method to typical core aeration. Whether you choose core aeration or liquid aeration, fall is a great time for this practice.
To overseed or not overseed that is the question… There is a reason I left this topic for the end. To some homeowners, the thought of a brown lawn just seems unbearable, and they look for ways to keep it green all winter. The most logical solution is to overseed with a cool season turf species such as annual ryegrass. In deciding to overseed your lawn, or not, some consideration should be made on what the advantages and disadvantages of doing so are.
The most important one is asking will the overseeding be detrimental or beneficial to the permanent lawn? Overseeding your warm season lawn with cool season grasses can actually delay next Spring’s green-up of the permanent lawn and may even weaken it. Just keep in mind that cool season turf species thrive at temperatures in the 60-70 degree range, so next spring when your permanent lawn begins to break dormancy, the overseeded turf species will be very competitive and act similar to any other weeds competing for nutrients, water, and space. Centipede turf is one of the most negatively affected turf types by overseeding. On the plus side, the temporary lawn could prevent erosion problems, prevent mud tracking into the home, and would provide the aesthetics of a beautiful green lawn all winter.
The turf species of preference for winter overseeding warm season lawns should be perennial ryegrass. Perennial ryegrasses are much finer textured than annual ryegrass cultivars. They generally have much better color throughout the winter, aren't as prone to clumpiness, and don't produce as many unsightly seed stalks in the spring.
Seeding rate for home lawns with ryegrass should be 8-10 pounds per thousand square feet. Seeding should be done when soil temperatures reach around 70 degrees which, as a general rule, will occur around the middle of October for much of South Alabama. If you apply a pre-emergent to help with winter weeds you will need to wait 6-8 weeks until overseeding.
Cultural practices of mowing, fertilizing, watering, and pest management must be continued throughout the winter for an overseeded lawn. Once the permanent lawn does begin spring transition the temporary lawn should be removed either mechanically or chemically. There are labeled herbicides available now that are very effective in removing cool season turf species from warm season permanent lawns, so you may want to consider using one of these in the spring to remove the ryegrass once the permanent lawn begins spring growth.