Overseeding

This column, “LBWA” (Leadership By Wandering Around), is based on the premise that, in order to find out what’s going on in the field, a parks and rec leader has to leave his or her desk and “wander around” the area of operations, talk to people, ask questions, and kick around ideas with the individuals in the thick of delivering services to the public.  So the author will bring up issues that may be common to many PRB readers and ask the leaders who are the readers to weigh in and share their knowledge and experiences. 

When turfgrass experts get together to talk shop, the subject of overseeding eventually comes up; odds are there will be varying opinions about this topic.

Ultimately, parks and rec maintenance managers have to do the research to see how and when overseeding might be in the best interest of their specific fields and in their unique climate; there isn’t a cookie-cutter solution. 

Climate Matters

In fact, overseeding warm southern-climate grasses is a totally different animal than overseeding cool northern-climate grasses.

“There’s not one answer for the United States because you have warm-season grass and cool-season grass, and each requires a very specific set of practices,” says Dr. Frank Rossi, a professor at Ithaca, New York’s Cornell University, School of Integrative Plant Science, Horticulture Section (https://www.sips.cals.cornell.edu). Known as “The Turf Guy,” he administers a broad-based research and education program focused on ecological aspects of turfgrass science.

“The system we designed and experiment with is really focused on those recreational fields that have a lot of repetitive traffic, fields that are very difficult for turf managers to manage,” says Rossi, adding that he and his team often work with individual rec departments on specific problems.               

He says, “They don’t generally have a budget like Yankee Stadium and Central Park, where they can re-sod a couple times a year … not to say we don’t recommend re-sodding at goal mouths and worn areas. But if you’re managing those high-traffic fields and the grass thins out so you can see the soil, dispersing grass seed in light amounts tends to maintain grass cover to make the fields safer for athletes, which is our number-one concern.”

Rossi makes it clear that his focus is on cool climate turfgrass familiar to cooler northern climates, such as Kentucky Bluegrass, not warm-climate grass, such as Bermuda, and that there is a distinct difference. He says that, while there is a cosmetic purpose in overseeding Bermuda to keep that nice green color year-round and extend the growing season, in cooler weather it’s more about survival.

“Overseeding in northern climates, you’re just looking for grass,” he says. “The fields are worn out from constant heavy traffic, and you can’t fertilize because there’s no grass to fertilize; you can’t move traffic patterns because the goal posts are stuck in the ground or the goalie is in the same place, so it wears out. This excessive wear results in no grass if you don’t overseed.”

Rossi explains that much of his department’s work focuses on scholastic sports, because in New York pesticide use is not allowed on school grounds; because of that, he says, “We’ve launched a lot of educational efforts to help field managers be better able to maintain safe fields for athletes, and one of the ways to do that is to overseed.”

Use of Bermuda grass for sports fields extends from New Jersey and Maryland southward to Florida and westward to Kansas and Texas and western states, according to the Texas A&M Agrilife Extension Service. Under irrigation, its distribution extends westward to southern New Mexico, Arizona, and to most major valleys in California. The development of more cold-tolerant, turf-type varieties of Bermuda, such as U-3 and Midiron, has increased interest in the species near its northern limits. Lower winter temperature is the factor that limits the northward distribution of Bermuda.

Balancing With Bermuda

Like northern grasses on youth-sports fields, Bermuda takes a beating from large and small feet, but warmer climates tend to extend playing seasons almost year-around, so the need to overseed is strong.

“Everybody wants that silver bullet, that perfect grass that will die out when we want it to and allow Bermuda to green up,” states Kevin Morris, Executive Director of the National Turfgrass Evaluation Program (NTEP) in Beltsville, Md. Morris has been involved for more than 30 years in evaluating grass for all different uses. He’s been watching the grass grow a long time—since he got out of college.

NTEP (www.ntep.org) is a non-profit turfgrass research program that has expanded to the evaluation of 17 turfgrass species in as many as 40 U.S. states and six provinces in Canada. Information, such as turfgrass quality, color, density, resistance to diseases and insects, tolerance to heat, cold, drought, and traffic, is collected and summarized annually. This information is used by organizations in 30 countries. Local and state government entities, such as parks and highway departments and a variety of other groups, use NTEP for locating resource-efficient varieties.

“We perform our evaluations primarily on research grounds at land-grant universities,” says Morris. “We find that at university facilities we have better control of the wide scope of factors that affect turfgrass and we need that control in order to get the kind of data we need. It would be difficult to do that on sports fields in heavy use, though we do some experiments on golf courses.”

From an academic perspective, Morris says that overseeding is “environmentally responsible. Some people view the use of herbicides or pesticides as damaging to the environment, and that’s debatable, but putting down healthy turf grass is never debatable.”

“We support overseeding,” says Morris. “People overseed with perennial rye grass or tall fescue, either over a stand of that type of grass or over Bermuda, so they get good green color or cover over winter, to hold soil, or make a safe playing surface—it’s much safer to play on grass than on dirt or weeds.”

However, Morris tempers that supportive statement in favor of overseeding with a cautionary note:  “Overseeding can arrest the growth of Bermuda as it tries to green up with warmer weather. It is always a challenge because you are trying to grow two or even three species of grasses at once, and you don’t want to lose the cool-weather grass until the Bermuda is ready, and it is all very dependent on weather patterns. If you can get away without overseeding, that is preferable.”

However, when youth-sports associations and parents are clamoring for green fields for winter or early spring soccer, baseball, lacrosse, etc., overseeding may be a good option. “However, overseeding dormant Bermuda has declined nationally over the past five or 10 years, largely due to cost,” says Morris. 

Cost factors include water, fertilizer, pesticides or herbicides, manpower and equipment, and fuel usage; some estimates put the cost at $700 or more per acre. Over time, this can run into significant funding. “Where overseeding is done for purely aesthetic purposes, it becomes hard to justify the cost,” Morris notes.

High Expectations

Tom Kuhl oversees 21 full-sized and several variable-sized sports fields for the city of Fairhope, Ala. In this upscale community on the eastern shore of Mobile Bay, expectations from citizens are high. Kuhl understands the pros and cons of overseeding, and the balance is in favor of overseeding with rye grass.

“We overseed all our fields, but it’s an aesthetic measure,” notes Kuhl. “It adds color to the fields where the Bermuda has gone dormant.” 

He and his department begin overseeding in mid-October when the nights and ground temperatures begin to cool.  “It depends on the weather and what’s happening on the fields,” says Kuhl, who has been with the department for 17 years. “For example, our youth soccer doesn’t really end until November, so we have to hold off.”

However, Kuhl concedes that the decision to overseed is a trade-off. 

“Our citizens expect to be playing on green fields, and that’s what we give them,” he says. “But it definitely stunts the growth of the Bermuda grass come May or June when it starts to green up.”

The Cornell University website (https://www.cals.cornell.edu) notes that a widely accepted concept is that 25 events on a native-soil football field is the limit for optimum turfgrass recovery. The grass cannot recuperate quickly enough when used for games, practices, gym classes, and other recreational activities. So overseeding must be done on a routine basis.

Research at Cornell and other universities found that overseeding weekly under high-traffic conditions, such as those on recreational fields with either perennial ryegrass or tall fescue, provided excellent season-long turf density.

Morris from NTEP says that organizations such as his and others have been working on developing a perennial grass that will give good color and will go out gracefully when it’s time for the Bermuda to step in.

“Genetically, there is not a lot of difference between annual and perennial rye grass, so we are constantly trying to come up with a grass that has the characteristics of the perennial to give good color and those of annuals, which will go out easier,” says Morris. “A good manager will use some of both and may add herbicides to assist cold-weather turfgrass transition out and give the Bermuda a better chance of coming in. More and more, people are working to try and keep rye grass as long as possible—there’s good and bad with that because once you start with rye grass, it will always be there to deal with. There simply is no silver bullet.”

Randy Gaddo served for 15 years as a director in municipal parks and recreation after retiring from 20 years in the U.S. Marine Corps. He earned his Master’s degree in Public Administration and is now a full-time photojournalist living in Bay Minette, Ala. Reach him at (678) 350-8642 or cwo4usmc@comcast.net.