Frost on the Grass: Why Golf Courses Delay Tee Times

Every fall I'd stand at the first tee at sunrise with a line of golfers asking the same question: "It's just frost. Why can't we go out?" The answer is that a footprint on frosted grass isn't just a footprint. It's a few hundred broken leaf blades, and on a putting green, it's a track of dead grass that shows up two or three days later.

What frost does to grass

A blade of grass is mostly water. On a cold, clear night, the leaf surface drops below freezing and ice forms on it and inside the plant's cells. A frozen blade is stiff and brittle.

When you step on it, the frozen tissue cracks. The cells rupture, the blade can't recover, and over the next couple of days it turns brown. A golfer walking a green on a frosty morning leaves a trail of dead footprints that everyone else putts over for a week. A cart driving across a frosted fairway leaves two brown tire tracks.

Once the frost melts and the plant thaws out, it's flexible again and you can walk on it without hurting it.

Why courses delay instead of close

Frost usually burns off within an hour or two of sunrise, faster on a sunny morning, slower in shady spots or low areas. So most courses hold tee times until the grounds crew says the frost has lifted. That's why tee times on cold mornings slide back, and why the first groups out sometimes play the holes in a different order to stay out of the shade.

Some courses lightly irrigate greens before dawn to melt frost faster. It only works in some conditions; on a very cold morning, the water can just freeze too.

What it means for your lawn

The same thing happens in your yard:

• Stay off the lawn on frosty mornings. Wait until the frost is gone before you walk, mow, or rake.
• Don't mow frosted grass. The mower's wheels crush the leaves, and the blade tears frozen tissue instead of cutting it.
• Keep the dog run off the lawn on frosty mornings if you can, or give the dog a path.
• Don't park on the grass or drive a lawn tractor over it until it thaws.
• Deliveries and kids happen. A few footprints won't kill your lawn; established grass grows the damage out once growing weather comes back. It's repeated traffic in the same spots that leaves bare paths.

Frost vs. dormancy

Frost is a short-term thing. Dormancy is the long-term state cool-season grass goes into after a few weeks of cold, when it stops growing and turns tan. A dormant lawn can still be damaged by heavy traffic, especially when it's frozen, but it's not as fragile as a lawn that's actively growing and gets hit by an early frost.

The fall months, when the grass is still green and growing but nights dip below freezing, are when frost damage shows up most.

The little things grounds crews do

• Flags or ropes across frosted areas to keep people off.
• Moving walking paths around shaded spots that stay frosty all morning.
• Scheduling mowing later in the day when frost is likely.

At home, the simple version is the same: let the sun do its work before you get out there. Your lawn will thank you in spring.

Once the season is winding down, see when to stop mowing for the season and how golf courses put greens to bed for winter.

Photo: Frosty morning on Peebles golf course - geograph.org.uk - 6348195 by Jim Barton, CC BY-SA 2.0.

Related: 7 Golf Course Techniques You Can Safely Use at Home