How do frost warnings affect harvest timing?
Written by
Benjamin Miller
Reviewed by
Prof. Martin Thorne, Ph.D.Frost warnings have a complete overhaul of potato harvest priorities and prompt urgent decisions. A light frost can damage the foliage, but tubers can survive, while a hard freeze can kill the entire crop. I lost a season's worth of work when I experienced a sudden frost prediction. Knowing these thresholds will help protect your investment in the harvest.
Forecast-Based Actions
- Light frost (28-32°F/-2-0°C): Apply 6-inch straw mulch immediately
- Hard freeze (<28°F/-2°C): Harvest all tubers within 24 hours
- Soil freeze warning: Harvest before ground hardens
- Unexpected frost: Cover plants with frost blankets overnight
Post-Frost Handling
- Damage assessment: Cut tubers to check for translucent flesh
- Separation requirement: Isolate frost-exposed potatoes
- Curing adjustment: Reduce to 7 days at 60°F (16°C)
- Cooking rule: Use frost-touched potatoes within 2 weeks
Mulching acts as important insulation against light frosts, and straw should be applied to or placed around the plant bases, or at least 12 inches outside the base of the plant. This protects shallow tubers. Decorative blankets (fleece row covers) can provide further protection. I've saved crops at 30°F (-1°C) using this method. Remove mulch after the danger has passed to continue the maturation process.
As soon as hard freezes threaten, harvesting should begin. Harvest from the outside row inward towards the planted area, as the tubers on the perimeter will freeze first. Harvest tubers before noon when the soil is warmest. Discard any tubers that feel soft or show ice crystals. I'll immediately process any salvable frost-exposed potatoes in frozen products on the same day.
Check forecasts using trusted sources, such as NOAA Weather Radio. Frost risk rises when temperatures are less than 36°F (2 °C), clear skies prevail with calm winds. I set alerts on cellular devices for frost warnings around the start of the harvest season. This prior notification gives time to take protective measures.
Read the full article: When to Harvest Potatoes: 6 Key Signs
