How much damage frost really causes a golf course (and your yard), according to a golf-course superintendent

Welcome to Super Secrets, a GOLF.com series in which we pick the brains of the game’s leading superintendents. By illuminating how course maintenance crews ply their trades, we’re hopeful we can not only give you a deeper appreciation for the important, innovative work they do but also provide you with maintenance tips that you can apply to your own little patch of paradise. Happy gardening!

Neither rain nor heat nor gloomy looks from disapproving spouses can keep avid golfers from their appointed rounds. But frost! Frost will do it. When it forms on courses, it often means delays.

But what’s the deal with frost? When and where is it most likely to appear? What problems does it pose? How do superintendents deal with it? And what, if anything, should homeowners do about it in their yards?

Rick Tegtmeier is a Certified Golf Course Superintendent and Master Greenkeeper (not many people have earned both titles). He’s also the director of grounds at the Des Moines Golf & Country Club, in Iowa, which hosted the 2017 Solheim Cup.

Given where he works, Tegtmeier has plenty of experience with frost. We asked him for the cold, hard facts.

1. It doesn’t have to be freezing for frost to form

Frost typically forms on turf over the course of chilly nights when the grass itself gets colder than the surrounding air. Any number of factors help create those conditions. Plain old temperature, of course, but also dew points, wind speeds, humidity and cloud cover. And then there’s the biggie: Wet Bulb temperature, which, as Tegtmeier puts it, “is the temperature air cools to when you add water to the equation.” You know how the air feels colder when you lick your finger and hold it out? Same thing happens when grass gets wet. The surface temperature of the plant drops to the Wet Bulb temperature. If it drops low enough, frost can form (all the more likely in shaded or lower-lying areas of the course), even if the air temperature hasn’t plunged below 32F.

2. It’s always coldest before the dawn

Lifestyle

That poetic-sounding saying is grounded in scientific fact. When the sun goes down, the earth starts cooling off and continues doing so until the sun comes up again. Tegtmeier and his crew are mindful of this when they head out on their pre-dawn maintenance shifts, knowing that the frost-less course they first encounter might become a frosty course while they’re in the middle of their work. “We’ve definitely gotten caught out there by frost,” Tegtmeier says. “It’s not there when we get started, but it forms while we’re out there.” When that happens, they’ll turn to other tasks, such as edging cart paths or tending mulch beds, that don’t involve treading or riding over frosty turf.

3. The clearer the night, the frostier the dawn

You’ve probably noticed that frost delays are more common after clear, crisp nights. That’s because clouds trap heat, warming the atmosphere. If it’s overcast at night, you’ve got a better chance of being in the clear for your early morning tee time. If, on the other hand, the air is crisp and you can see the stars, don’t be shocked if you’re delayed by frost on your course at dawn.

4. What’s the damage?

That depends on a range of factors, including the varietal of turf, the health of the grass, the severity of the frost and amount of activity the frosty turf endures. But here’s the gist: When grass gets frosted over, the water in its plant cells can freeze and expand. If you mow that grass in its frigid state (or trample on it, or ride your cart across it), those icy molecules can shatter. That’s not broken glass. It’s broken grass. That doesn’t mean you’ve killed the turf, which, in most cases, will recover. But you can see the impact soon after in discoloration. “I don’t want to say it’s just an aesthetic issue, because you can obviously do some structural damage to the plant,” Tegtmeier says. “But most often the impact is visual.” That impact is more readily apparent in the longer grass of the rough, Tegtmeier says. It’s also more obvious when the damage is caused in early season frosts, in, say, late September or October, when the grass is still succulent and growing, and the discrepancy between healthy and unhealthy turf is clearer. It’s much less apparent later in the season, when the turf has started going dormant.

As a general rule, Tegtmeier says, if there’s frost on the ground at Des Moines Country Club, golfers are not allowed on the course. “Of course, if it’s just a tiny patch in the shade of a tree somewhere, we’ll just ask the golfers not to drive or walk through it,” Tegtmeier says. “We try to let common sense prevail.”

But many other courses are looser with the rules, allowing golfers out in frosty conditions, most likely because they need the greens fees. “The operator might just decide, I’d rather deal with the frost damage than lose the revenue,” Tegtmeier says.

5. How to deal with frost at home

Back in the good old days, when print was king, Tegtmeier could tell from the discolored footprints in his neighbors’ yards that the newspaper boy or girl had trampled on the grass when it was frosty. Not the end of the world. But if it’s not something you want, you could employ a superintendent’s trick and spray your lawn lightly with a hose. Maintenance crews sometimes do that to get frost off a green, Tegtmeier says. But for a homeowner, he adds, that’s pretty much just a waste of water. “It’s not like you need to use your lawn for revenue,” he says. “You’re better off doing what most of us do at the golf course and just wait for the sun to come up and the frost to melt away.”