To seed or not to seed, that is the question

Published 11:05 am Thursday, August 25, 2022

To seed, or not to seed, that is the question:

Whether ‘tis nobler in the mind to suffer winter with no green

The slings and arrows of outrageous shade and competition,

Or to take refuge in the dormancy of our sleeping warm season grass…

Well, obviously I’m not anywhere near as cool as Shakespeare, my poem may not even make any sense to you! However, if you are questioning whether to overseed your warm-season lawn this fall, you may want to keep reading.

I field these questions every year from homeowners who want to use some green so they can see green in their lawns all winter. While this is not necessarily a standard practice in home lawns, it is on golf courses across the east. In fact, did you know that the Master’s Tournament is played on perennial ryegrass? That beautiful lush grass that they play on is seeded into a base of Bermuda grass every fall to prepare for that special tournament. They also spend millions to maintain the Bermuda throughout the year to make this possible.

Overseeding is the process of seeding into a stand of established turf. This is a standard practice in cool-season grasses to help keep them nice and full. But, this practice is not necessarily recommended in warm-season turf. Research-based information tells is that overseeding ryegrass into warm-season grasses should only be done in Bermudagrass lawns. However, that never stopped most of the folks I talk to! I think unfortunately, this becomes an, “I can show you better than I can tell you type of thing.” You see, by their very nature, warm-season grasses act and behave much differently than there distant cool-season cousins. Warm-season grasses are green and growing like crazy during the summer. They are fairly intolerant of shade across the spectrum and begin to set-up for winter dormancy as early as September. This is why they turn brown in the fall and green in the spring. They cannot tolerate the cold but they are also intolerant of the lower levels of light throughout the winter season. In fact, some hybrid Bermudagrass is already starting to go dormant right now. By the first week of September some of these hybrids will be almost completely brown. Other warm-season grasses will begin to slow down but won’t necessarily brown-out until after the first frost.

The big four warm-season grasses include Bermudagrass, Centipedegrass, Zoysiagrass, and St. Augustinegrass. There are varying degrees of shade tolerance among the cultivars of the different species but as a general rule, St. Augustine has the best shade tolerance and Bermuda has the least tolerance. This being said, if your St. Augustine is not receiving at minimum of five to six hours of direct sunlight during the summer, it will be thin and patchy from shade stress. Another little-known fact about the grasses that relates directly to shade tolerance is mowing height. Bermudagrass, zoysiagrass, and centipedegrass like to mowed just about as low as you can get them with your residential mower (1”-1.5”). St. Augustinegrass on the other hand would like to be between 2.5” and 4”. If Bermudagrass is allowed to grow this high, it will act like a tree in that it will be dead underneath and only green on top. This will give the appearance that the lawn has been scalped nearly every time you mow the grass.

If you do have Bermudagrass and decide the you want to overseed to have that beautiful, lush green grass all winter, here are a few pointers. You want to use perennial rye and not annual ryegrass. There are two reasons for this; 1) perennial ryegrass has better color and overall quality than annual and 2) annual ryegrass is allelopathic in that it can hinder the growth of other plants. Seed roughly 30 days prior to the first average frost. This is going to be sometime between September 15th and October 1st. Use five pounds of seed per 1,000 square feet sown in different directions (apply half in lines going one direction and then half walking straight lines perpendicular to the first application, i.e., apply in a checkerboard fashion). Water frequently to germinate and then back off on the watering. Apply a half pound of nitrogen per 1,000 square feet after the second or third mowing. The first mowing should be when the grass reaches 2” tall. Mow thereafter to 1 – 1 ½” when the grass reaches 2- 2 ½” tall.

If you are going to go down this road, you need to think about a strategy for reestablishing your permanent lawn. There are a few things that you can do to stress the ryegrass and help it phase out. Do not fertilize after January. Keep the grass on the dry side, if possible, in the spring. Keep the grass mowed down to 1” in height but be sure not to scalp the permanent lawn. If there is a wet, cool spring, you may need to kill the ryegrass by applying an herbicide. Many of the “SU” herbicides will work well. These are those with active ingredients that end in “-sulfuron” such as flazasulfuron, foramsulfuron, rimsulfuron, metsulfuron, etc. If you do not take care of the ryegrass, you will end up with a few islands throughout the lawn where it will survive, becoming unsightly and a pain to mow. I should also mention, that once you go this route, it is hard to stop. If you decide you don’t want to overseed again, you will have several years in which the ungerminated ryegrass from your previous applications decides to germinate leaving you with what looks like weeds all over your permanent lawn. To prevent this situation, you would need to look at using a pre-emergent in early to mid-September.

If you have horticulture a question or would like a tour of the teaching garden, call the Extension Master Gardener Volunteers in Beaufort County or Gene Fox, the Area Consumer Horticulture agent at (252)946-0111 or please email Gene at gene_fox@ncsu.edu. Our Extension Master GardenerSM Volunteers in Beaufort County offer their Greenline service on Mondays and Wednesday from 10:00 – 12:00. Check out our Blacklands Area Horticulture page on Facebook, we have been revamping this and would love to have your feedback and questions there! Give us a call and let us help you GROW!