Which Crops to Cover on a Frost Night
Cover light-frost greens and brassicas. Pick tender crops first. Leave hardy kale and roots in. Thresholds: light frost 32F, hard freeze about 28F.
Published by ThriveThyme
frost night row cover season extension fall
Which Crops to Cover on a Frost Night
Cover before dusk when the forecast low is 32F or below. Uncover or vent by mid morning.
Light frost is about 28 to 32F. Hard freeze is below about 28F for several hours. Kill temperatures below match the Frost Harvest Desk and extension charts from Minnesota, Purdue, Ohio State, and Maryland.
Pick First (Do Not Rely on Covers)
These are damaged near 32F. Harvest usable fruit and leaves. A light cover or cloche may buy one light frost night, not a hard freeze.
- Tomatoes, peppers, eggplant
- Basil (leaves blacken in the 40s F)
- Cucumbers, summer squash, beans, corn, okra
- Melons, watermelon, pumpkins still on the vine
- Sweet potatoes: dig before frost or soil below about 50F
Cover These (Light-Frost Crops)
These ride out a light frost with medium row cover, a low tunnel, or a cold frame. Cover them on frost nights. Harvest or cover well before a hard freeze into the mid 20s F.
- Lettuce, Swiss chard, arugula, bok choy
- Broccoli, cauliflower, cabbage (firm heads handle more cold than loose ones)
- Beets, radish, kohlrabi, celery, cilantro, peas
Leave In (Hardy); Cover Optional
These take hard frost into the low 20s F. Flavor often improves after frost. Cover or mulch only if you want a longer harvest window.
- Kale (about 15 to 20F), collards, spinach
- Brussels sprouts, leeks, parsley
- Carrots, parsnips, turnips: mulch after frost and dig before the ground freezes solid
Full hard-freeze list: Which vegetables survive a hard freeze.
Cover Choice by Job
| Job | Use |
|---|---|
| One light frost on greens | Medium row cover pinned to the soil |
| Many frost nights on a bed | Low tunnel with medium or heavy fabric |
| Salad greens you check daily | Cold frame with daytime venting |
| A few tender plants for one night | Cloche, milk jug, or pot (pick if a hard freeze is coming) |
Compare methods: Cold frame vs row cover vs low tunnel.
Night Checklist
- Check the forecast low (and your first frost date).
- Pick tender crops.
- Cover light-frost beds before dusk.
- Vent or remove covers by mid morning.
- Re-cover before the next cold night.
Open the Season Extension Desk for a zone countdown, cover degree gains, and a My Garden filter.