On the night of October, temperatures plunged below freezing in Bismarck, delivering the first hard freeze of the 2025 fall season. Gardeners across the city are being strongly advised to cover or move sensitive plants before overnight lows cause irreversible damage.
According to climatological data, Bismarck’s average first fall frost date is around September 25. But this year’s freeze moved in early, catching many home growers off guard. This freeze isn’t just a mild frost: “hard freeze” conditions generally mean prolonged sub-32 °F temperatures — enough to harm or kill many warm-season plants. For local gardeners, that means time is short. Tender annuals like tomatoes, peppers, squash, and other frost-sensitive crops are at highest risk. The National Weather Service has issued freeze/frost warnings for central and western North Dakota, including the Bismarck area.
“I woke up to blackened leaves on my tomato plants — I should’ve covered them last night,” said Anne Carlson, a local gardener in the North Bismarck neighborhood.
What Gardeners Should Do Now
Harvest vulnerable crops now — if any fruit or veggies are close to maturity, pick them before they’re lost.
Cover plants with breathable fabric, burlap, sheets, or horticultural fabric. Avoid plastic directly touching foliage.
Bring potted plants inside or into garages/greenhouses.
Water the soil a little before freeze — moist soil holds more heat than dry soil.
Remove covers early in the morning so sunlight and airflow can reach the plants.
Watch local forecast updates hourly, as conditions may vary across Bismarck neighborhoods.
Gardeners who act quickly may still extend the season for several more weeks — but those who delay risk losing key crops entirely.
The arrival of Bismarck’s first hard freeze is a stark reminder — fall is here in full force. Local gardeners still have a window to protect tender plants from frost damage. Cover now, act smart, and you may salvage what’s left of this year’s harvest.
