Does artificial turf freeze? What 150-plus freezing nights do to turf, base and drainage

01What actually freezes: the turf, or the water in it?

The water. Turf blades and backing are plastic. FieldTurf, which makes synthetic sports turf, says the components of its turf “do not freeze,” while the moisture within the infill does (FieldTurf).

On a January morning a turf yard has three layers that can hold ice:

• The infill. The sand or granules between the blades keep some water after rain, melting snow or a rinse. Frozen, the infill stays put and stops water passing through it.
• The base. The crushed rock under the turf is there to carry water down and away. Water still in it at dusk freezes in place.
• The soil under the base. Northern Colorado clay holds water longest, and it is the layer that moves (next section).

The plastic does change in the cold. SIS Pitches, which builds synthetic sports surfaces, says frozen synthetic grass can be used when the footing is adequate, but heavy use should be discouraged because the fibre is “relatively brittle at low temperatures” (SIS Pitches). At home that means:

• Don’t drag patio furniture, a grill or a loaded sled across frozen turf.
• Don’t chip or scrape ice off it with a shovel, rake or ice chopper.
• Treat frosty or icy turf like an icy sidewalk until the sun gets on it.

Clearing snow and what is safe to melt ice with have their own page: how to clear snow off artificial turf.

02What do 150-plus freezing nights and chinook thaws do to the base?

A Northern Colorado winter isn’t one long freeze. It freezes at night and thaws by afternoon, over and over, from October into May. NOAA’s 1991–2020 normals for the four stations nearest most of the area:

*Our arithmetic: nights at or below 32°F minus days whose high never gets above 32°F, which leaves the days that freeze overnight and climb above freezing. Station data: Fort Collins, Loveland 2N, Longmont 2 ESE, Greeley UNC.

Chinooks sharpen the swings. The Colorado Climate Center says temperature rises of “25 to 35°F within a short time are not uncommon” when these winds come down off the mountains (Colorado Climate Center). A January chinook can thaw the top of a yard in an afternoon while the ground a few inches down stays frozen.

How deep the cold reaches: Larimer County sets a minimum frost depth of 30 inches below grade for footings (Larimer County), and Weld County’s design criteria use a 30-inch frost line (Weld County). Those are design figures for buildings, not a measurement of your yard, but a turf base sits well inside that depth.

Why clay is the part that moves

Frost heave needs three things at once: a soil with a lot of fine particles, freezing that reaches into it, and water. Clean sand and gravel with few fines are not frost susceptible (Pavement Interactive). Clay is fine-grained soil, and the Colorado Geological Survey says expansive clays can swell up to 20% by volume when wet (CGS). Put wet clay under a base, in a climate where the air crosses freezing on well over a hundred days a year, and a flat lawn of turf can grow a hump by February.

What that asks of the base:

• Clean, porous rock, not a mix full of fines. Firestone’s code, for one, requires turf over “a compacted and porous aggregate base” at least 3 inches deep (Firestone Development Code 16.6.4). The rest of that standard is in our turf spec sheet guide.
• Somewhere for water to go when the clay below is frozen or already soaked: grade that falls away from the house, and downspouts that don’t empty onto the turf.
• Depth and prep suited to the soil. Our guides to what base goes under artificial turf and artificial turf on clay soil go through both.

Ask an installer what the base is made of, how deep it goes on your clay, and where water leaves the turf area in March, when the top has thawed and the ground below hasn’t. A good answer names the material and the depth and traces the water to a place it can actually go.

03Why does water pool and turn to ice on turf in winter?

Because the drain is frozen. SIS Pitches says rain or a quick thaw on frozen synthetic grass can flood it: the sand in the infill is still frozen and “prevents the water draining,” and it drains normally once the infill thaws. The same happens deeper down. In a sudden thaw the ground melts from the top, and the frozen soil beneath traps the meltwater, so it can only run sideways or across the surface (Pavement Interactive).

Where it shows up in Northern Colorado yards:

• North of the house. The strip in the house’s winter shadow thaws last. Meltwater from the sunny side or the roof runs onto it and refreezes as a sheet.
• Under downspouts. One outlet can put a whole roof’s snowmelt onto one patch of frozen turf.
• Low spots. A dip that holds a puddle in July holds ice in January.
• Dog spots and rinse areas. Water added on a cold day freezes in the infill.

What to do about it:

• Let sheet ice melt off. Chipping it tears blades.
• Extend or redirect downspouts to discharge past the turf before next winter.
• Note where water stands after the ground thaws. Ponding on frozen ground is expected; ponding on thawed ground in April is a drainage problem, covered in what happens to artificial turf when it rains.

04Can dogs keep using turf in January?

Yes. Cold doesn’t hurt the turf, and dogs can use it all winter. What changes is the urine. In summer it drains through. In winter it freezes in the infill and the top of the base and waits there, until the first chinook afternoon or the March thaw lets it all go at once, so a dog area that seemed fine in December can smell in March.

• Rinse on an above-freezing afternoon, early enough for the water to drain before dark. Rinse water that meets frozen infill sits on top as ice. Whether watering rules cover a turf rinse is in do you have to water artificial turf.
• Pick up solids as you go. Waste frozen on top lifts easily; waste buried under a week of snow doesn’t. More in dog poop on artificial turf.
• Keep a path clear from the door to the dog’s spot after each snow, with a plastic shovel or a broom.
• Plan a spring deep clean for the smell the thaw brings back: getting dog urine smell out of turf. How a dog area is built to drain in the first place is on our pet turf page.

05What should I check once spring arrives?

Wait until the hard freezes are mostly over. In half of years the last 32°F night comes by about May 2 at the Fort Collins and Greeley stations, May 7 at Longmont and May 10 at Loveland. Spring snow isn’t done early either: CSU Extension says heavy, wet late-spring snows are common in Colorado (CSU Extension), and at the Fort Collins station 17.2 of the 51.4 inches of snow in an average year falls from March through May.

Then, after a few dry days, crouch at one edge and look across the turf at a low angle:

• Humps, ridges or dips that weren’t there in fall. A hump that settles once the ground has fully thawed was probably frost heave; one that stays, or a dip that holds water, points to the base. See why turf sinks or goes uneven.
• Ripples or waves in the turf itself: wrinkled or rippled turf.
• Seams and edges. Walk every seam and every edge where snow was pushed or piled: turf edges lifting and visible seams.
• Puddles after the first spring rain, now that the ground has thawed.
• Bare-looking patches where shoveling or snowmelt moved infill: how often to add infill.
• Flattened blades under old snow piles: matted artificial turf.

Photograph anything you find, with the date, before you call anyone about it; an installer will want to see how it looked. A backyard putting green goes through the same winter, and its care through the year is on our putting greens page.