To cover, or not to cover (Turfgrass management)

Greens are considered the heart and soul of a golf course. While most club members and daily-fee players will overlook a few brown patches on fairways or tee boxes, they won’t turn a blind eye when it comes to the conditions of putting surfaces.

That’s why golf course superintendents spend countless hours and a considerable portion of their annual maintenance budgets on the upkeep and enhancement of greens.

In the Northern regions of the United States, maintaining greens sometimes includes placing covers on them to protect them against harsh winter weather and speed up the greening process during early spring. Covers also stimulate grass growth on newly installed or renovated greens, especially those that are seeded late in the season.

The greenhouse effect created by green covers allows the grass underneath to breathe and retain a certain amount of heat and moisture, even on cold days. The end result is faster germination of seeded areas and deeper and stronger root development.

Using green covers has several benefits. They allow a superintendent to get the course playable more quickly earlier in colder climates while reducing the risk of winterkill from wind and ice. In an industry where time is money, being able to open a week earlier in the spring and having greens ready to putt on can mean more business and a significant increase of cash flow during a usually slow period of the year.

A recent study by G.W. Hamilton, Jr., Ph.D., and R.B. Raley at Penn State University showed that turf covers increase soil temperature underneath the cover by about 2 to 3 degrees, and that such a variance would induce spring green-up and growth when temperatures begin to increase. By the same token, a lower minimum temperature of covered greens versus those that weren’t covered could help prevent certain types of winter injuries on turfgrass, such as direct low-temperature kill. The study showed that color on putting surfaces was enhanced significantly by the use of turf covers, thus providing an added aesthetic bonus.

Reasons for use
In a Midwestern area such as Columbus, Ohio, there are several reasons why superintendents use green covers. One is to stimulate early green-up, and another is the enhancement of turf establishment on greens that might have been seeded in the fall, says John Street, a turfgrass extension research specialist at Ohio State University.

Street believes covering greens also helps minimize the temperature fluctuations of the soil and might reduce the loss of annual grasses, as well as almost eliminate the possibility of ice damage.

“If you build a green or refurbish one and plant grass in the late fall and it’s just starting to come up as winter is approaching, it’s a no-brainer to cover that green,” says Dave Miner, an extension turfgrass specialist and professor at Iowa State University. “Another reason would be to moderate the temperatures in cold climates so you don’t get those huge swings in temperatures that can damage greens.”

One of the main reasons superintendents in the Midwest cover greens is to prevent wind desiccation, Miner says.

“The wind can really howl around here in the winter, and the farther west you go – out to Montana and that area – the drier the air gets. And that, plus the wind, can really cause damage to greens,” he says. “Covers are ideal for preventing that type of damage.”

Steve Harrer, golf course superintendent at the Minnehaha Country Club in Sioux Falls, S.D., is a believer in green covers, too.

“We cover all the greens, the practice greens and even 10 sets of tees,” Harrer says. “From the time we started covering them they have performed better, and that’s why we just kept purchasing more covers. We get an earlier green-up, and the greens are healthier. And we notice a huge difference with the green-up in the spring on the tee boxes. I used to have dry spots that we would have to fight. Now, I don’t seem to be doing that as much. The members notice, and that’s what I’m most pleased about.”

Superintendents in Maine can experience brutal winter weather. Thus, the maintenance staff at Sugarloaf Golf Club in Carrabassett Valley, Maine, covers a number of putting surfaces to guard against ice and snow damage.

“We covered four greens last year,” says Jim McCormack, assistant superintendent at Sugarloaf. “We have a few problem greens, and they came through the winter in great condition, although last winter wasn’t a particularly tough one. But it definitely helps. And anything we can do up here to get the soil warm quicker in the spring is a plus.”

Brian Zimmerman couldn’t be more pleased with the results green covers produce at the courses he oversees. Zimmerman is the operations manager for the Milwaukee County Park System, which oversees a number of courses in the city, including Brown Deer Park Golf Club, the site of the PGA’s annual U.S. Bank Championship.

“They have worked extremely well,” he says. “We use a variety of lightweight, relatively inexpensive covers at several of our courses to increase soil temperatures and get the seed to pop early in the spring. We also have some worries about wind desiccation on some of our troublesome greens, such as those with humpback designs, so we’ll cover them early in winter to give them a little more protection.”

To Bryan Barrington, golf course superintendent at the Golf Club at Oxford Greens in Oxford, Conn., the true benefit of green covers is to promote growth, especially on troublesome or newly seeded greens, giving them a head start going into spring.

“I covered my eighth green last winter and left it on as long as I could before we opened because we did some seeding late in the fall. The green is crowned to the point where moisture falls to the edges and backs up a little bit. The cover helped protect the surface.”

However, Barrington says green covers aren’t always needed.

“I know when you get up into Maine, they get some crazy weather, and they might need a thick cover on their greens,” he says. “Personally, for most courses, my thinking is to let the plant harden naturally in the cold and go through winter that way. The grass won’t be shocked come spring.”

Cost factors
A number of companies manufacture turf covers for use on golf greens. Several will even customize the covers to ensure a perfect fit on the putting surface. Green covers are made of a wide range of permeable materials, from geo-textile fabrics to woven and solid polypropylene sheets. Most covers are treated to block ultraviolet light and designed to be rot and mildew resistant.

Green covers range in price from several hundred dollars to a few thousand dollars apiece. Covering all 18 greens on a golf course could cost tens of thousands of dollars. The covers generally are under warranty to last between eight to 10 years. They are also somewhat labor intensive, requiring a full crew to work several days placing them down in the late fall or early winter and removing them in early spring.

“You need to have the resources to put them on quickly before winter and get them off quickly in the spring, and then perhaps put them back on if you need to when the weather takes a turn,” says Kevin Frank, Ph.D., a crop and soil scientist at Michigan State University.

“There are usually a dozen of us, and it takes a couple of days to do all the covers,” Harrer says.

Although green covers aren’t a cheap investment, McCormack says they’re worth it.

“A few years ago, we spent between $40,000 and $50,000 on green covers,” he says. “But it’s worth the investment if it’s going to save greens and get the club open earlier.”

It’s all timing
The timing of installing and removing green covers is crucial to their overall success.

“Going into the winter, it isn’t quite as tough to judge when to put the covers on,” Frank says. “But you talk to superintendents, and they say spring can be tricky. If you take the covers off too early because it looks like there’s some growth underneath, you run the risk of having a cold night that can cause some burning.”

Street advises careful monitoring of the soil temperature and grass conditions under the covers.

“Most superintendents are going to do that anyway, although some might not think about it if they haven’t used them before,” Street says. “You don’t want the grass to get excessively high under the cover because then you might have some scalping and mowing injuries when you cut the grass. And you certainly don’t want to take the covers off too early and have a deep frost at night.

“Common sense will tell you that if you’re getting temperatures in March of greater than 75 degrees underneath the cover, you should pull them off during those periods and perhaps place them back on if the weather turns cold again,” he adds.

Harrer and his crew try to look three or four days down the road at what the weather will be before they take the covers off in the spring.

“Sometimes we have taken the covers off in late March, and sometimes we leave them on into April,” he says. “I’m always crawling around under there to see what’s going on. There will always be an initial shock to the grass no matter when you take the covers off. But I have never had anything terrible happen.”

The bottom line is that superintendents must come to their own conclusions when deciding whether or not to cover greens.

“One course is different from another, even if they’re only one mile apart,” Harrer says. “In some areas of Iowa, temperatures get warm during the winter, and green covers won’t work on golf courses. For us – we’re in God’s country – so it’s been great for us. I would advise buying one cover, trying it and see what happens and go from there.”

Superintendents have to make their best guess about whether or not to use covers, Miner says.

“Take your climate and location into consideration and make a decision,” he says. “You might want to just cover one or two problem greens.” GCN

John Torsiello is a freelance writer based in Torrington, Conn. He can be reached at jtorsiello@megahits.com.