August 25, 2026 · Updated September 13, 2026

Will one night of frost kill my plants

One night of frost kills tender crops like tomatoes, basil, and peppers, and leaves hardy plants like kale and established strawberries standing. Frost forms when plant tissue drops to freezing and ice ruptures the cells from the inside. Whether that happens in your garden depends on the low your yard reached, which can sit several degrees below the regional forecast.

What frost does to plant tissue

When a leaf cools to freezing, the water inside its cells turns to ice. Ice takes up more room than liquid water, so it pushes against and tears the cell walls. Once the sun warms the tissue the next morning, the ruptured cells leak and collapse, which is why frost-hit leaves look wet and then turn dark and papery.

Tender crops have no defense against this. Tomatoes, peppers, basil, and squash carry a lot of water in soft tissue and freeze at the first hard frost. Hardy plants work differently. Kale, spinach, and cold-adapted perennials pull water out of their cells and pack in sugars, which lowers the temperature at which their tissue freezes. That is why one frost night can wipe out half a bed and leave the row beside it green.

Whether your yard froze

The forecast reports the air temperature at a regional station, not the temperature at your plants. On a still, clear night the ground radiates its stored heat to the open sky, and the plants closest to the soil can end up colder than the reported air. A forecast low of 35°F can still deliver frost on your leaves.

Our own station reads 7°F below the forecast on most nights. Our published first fall frost date is October 22, but after that learned offset the effective date moves to September 30. The cold reached our beds on October 3, well ahead of the calendar date. Our coldest night of the year hit 3°F, so the plants still standing in winter earned it.

You can check how your area runs before you own a station. The microclimate checker gathers recent readings from home stations near you and reports how many degrees the area tends to sit above or below the forecast low. It shows the area trend and cannot promise the exact low at your plants. To learn your own offset, connecting a station lets Siltwell compare its readings against the forecast; the learned offset is trusted after about 14 overlapping days.

Which plants die and which shrug it off

Sort your beds by cold tolerance before the first frost, because the response varies by crop.

• Killed by a light frost. Basil, tomatoes, peppers, cucumbers, and squash. These blacken at the first frost and do not recover. See the tomato frost kill temperature for the exact numbers.
• Tolerate light frost. Lettuce, chard, and many annual flowers take a touch of frost with edge damage but keep growing.
• Improve with frost. Kale, collards, Brussels sprouts, and carrots convert starch to sugar in the cold and taste better after a frost.
• Overwinter dormant. Established strawberries, garlic, and hardy perennials go dormant and survive well below freezing once cold-hardened.

Match the plant to the low your yard reaches instead of the plant's headline rating. Reading your real low is the step most frost losses skip.

What frost damage looks like the next morning

Frost-hit leaves look water-soaked and limp at dawn, then dark and dry once the sun warms them. Tender growth droops first, and stems go soft where the water froze. Wait a day or two before you cut anything back. Some plants push fresh growth from wood that looked dead, and pruning too early removes tissue that would have recovered. Spotting frost damage walks through the signs in more detail.

Your next move depends on the crop in front of you. For a bed of tomatoes with a freeze warning tonight, either cover them or pick every fruit worth saving before dark. For hardy rows, do nothing and let the cold sweeten them.