November 1, 2026

What happens to plants in the winter when the ground freezes

Plants keep losing water all winter, and frozen soil stops them from replacing it. Evergreen needles and leaves stay on the branch, and on a bright or windy day they give water vapor to dry air. Roots can't draw water from ice, so the leaves dry out from the tips back. Gardeners call the damage winter burn. Deep watering before the ground freezes, mulch, and wind screens slow it down.

Why plants keep losing water in winter

Every leaf and needle has pores that let water vapor escape. Winter air holds little moisture, so the gap between a wet leaf and the dry air around it stays wide. Sun on a needle warms it above the air temperature, and a warmer needle loses water faster. Wind strips away the thin layer of humid air that sits on a leaf surface. With that layer gone, evaporation speeds up again.

Dormancy slows a plant down. Water loss continues anyway. Bare branches and the buried crowns of perennials lose water too, through bark and buds, at a slower rate than evergreen foliage.

How frozen soil cuts off the supply

Roots take up liquid water. Ice in the soil gives them nothing to draw on. Cold water is thicker and moves slowly, and cold root membranes let less of it through, so uptake slows even before the soil freezes. The plant spends water it can't replace.

Cells in the leaves shrink, then die from the tips and edges inward. That browning is winter burn, also called winter desiccation. It shows most on the side facing the sun or the prevailing wind. It often appears in late winter or early spring, weeks after the damage happened.

• New transplants. Their roots haven't spread into enough soil to bank water before the freeze.
• Containers. The whole root ball can freeze solid, so the plant has no unfrozen soil to draw from.
• Broadleaf evergreens. Large leaves expose more surface to sun and wind than needles do.

What dormancy does inside the plant

Shorter days and cooler nights signal deciduous plants to shut down. They pull nutrients back out of their leaves and seal each leaf stalk with a layer of corky cells, so the leaf drops. Buds harden behind protective scales.

As hardy stems and buds cool, water leaves each cell and collects in the gaps between neighboring cells. When that water freezes, the ice sits outside the cell walls, where it does less harm. Ice that forms inside a cell tears its membranes, and the tissue turns black and soft when it thaws. Our guide on whether plants hibernate covers dormancy in more depth, and what happens inside a freezing plant covers ice damage.

Why cold makes kale and carrots sweeter

Cold prompts hardy crops to break stored starch into sugars. Sugar dissolved in cell sap lowers the temperature at which that sap freezes, the same way salt lowers the freezing point of water on a road. The sugars also hold water inside the cell while ice forms around it.

Kale, collards, spinach, carrots and parsnips all sweeten this way after a run of cold nights. Tender crops such as tomatoes and peppers have no such defense, and they take damage around 32°F. Our guide to plants that live in the cold sorts crops by what they tolerate. If you have carrots in the ground, leaving them there over winter keeps that sweetness.

What our garden showed last winter

Our garden sits in zone 7a. The coldest night of 2026 came on January 9, when our station read 3°F. Our station runs about 7°F colder than the forecast, so the published lows understate how cold our beds get.

Rain held steady through the cold months. We logged 1.73 in in January, 2.88 in in February and 2.49 in in March. April brought 0.54 in. That dry April landed as the ground thawed and evergreens and early crops started growing again, so they drew down soil moisture that rain wasn't replacing.

Cold also arrives early here. In 2025 the published frost date for our area was October 22, and our beds saw frost on October 3, 19 days early. Plants that haven't hardened off by then meet a hard night with soft tissue.

What to do before and during winter

• Water deeply before the ground freezes. Soil that goes into winter moist holds a reserve the roots can reach on thaw days.
• Water on thaw days. Water at midday when the surface is soft and the air is above freezing, so it soaks in before night.
• Mulch the root zone. A few inches of shredded leaves or straw slows freezing and slows evaporation from the soil surface.
• Screen evergreens. Burlap set a little way off the plant cuts wind across the needles and shades them on bright afternoons.
• Group containers. Pots pushed against a wall or sunk into a bed freeze later and thaw sooner.

Our guide to watering plants during winter covers which beds need it first.

How Siltwell flags dry and cold spells

The dry-spell alert is free. It fires when the forecast shows under 5 mm (about 0.2 in) of rain across the next six days. In winter, that alert is your cue to check whether the soil has thawed enough to water.

Frost alerts run for every garden, free and Pro. At 17:00 local time Siltwell checks the forecast lows for tomorrow and the day after against your frost threshold, which defaults to 0 °C (32°F). On a free account you enter the offset yourself under Settings, Garden, Edit garden, Microclimate offset, using a negative number for a colder site. With a connected station on Pro, Siltwell learns the offset from the station's outdoor air temperature after about 14 days of overlapping station and forecast readings.

A dry-spell alert reads the rain forecast. It can't tell whether the ground under your hedge is frozen, so push a trowel into the soil before you water.

To find how much colder your yard runs, open the microclimate checker. The microclimate checker compares nearby home weather stations with the forecast model over recent nights and returns a range for your area. Enter its median as your manual offset, then check the evergreen on your windiest side after the next dry week.