Can radishes survive frost?
Written by
Julia Anderson
Reviewed by
Prof. Martin Thorne, Ph.D.Radishes have varying degrees of frost tolerance depending on their variety. For instance, summer varieties like Cherry Belle are injured when first exposed to 32°F (0 °C), while winter kinds, properly protected, such as Daikon, can withstand a temperature of 20°F (-7 °C). This is due to the presence of natural sugars in the radish that act as an antifreeze. I have harvested Black Spanish radishes, which have had a slight covering of snow on them.
The winter varieties of radish are naturally hardy and resistant to frost. Daikon, watermelon, and black Spanish all actively create even more cold-resistant chemicals as temperatures fall toward freezing. Frost makes the flesh sweet by converting starches into sugars. You should always mulch your plants before the first frost to protect your crops from potential frost wilts and to insulate the soil. I use 6 inches (15 centimeters) of straw for insulation. I sometimes cover lightly with row covering (like fabric or plastic) for a few days during a cold period.
Pre-Frost Preparation
- Mulch timing: Apply before first freeze
- Cover selection: Use frost cloth or row covers
- Hydration: Water deeply before freezing nights
- Location choice: Plant in south-facing slopes
Post-Frost Recovery
- Damage assessment: Check for translucent leaves
- Harvest timing: Wait 48 hours after frost
- Storage method: Refrigerate immediately
- Composting: Discard frozen summer types
Summer radishes need to be harvested promptly before the first frost. Their fragile, paper-thin skins become translucent instead of crunchy when frozen, plus roots turn mushy when thawed out. Always be on the lookout for cold snaps in the fall. I have weather apps on my phone that send alerts for frost, which is vital. Cover them up promptly when a different kind of cold threatens. And make sure to harvest all your summer types when the temperature drops toward freezing.
Long for a season. Sow winter kinds eight weeks before the first frost, or if you are setting out a crop for the late-maturing varieties, use cold frames. My unheated greenhouse produces radishes as late as December. In milder zones (5-7), your radish crop can be planted in September for a harvest in November. This will give you the full benefit of all of the kinds that are hardy in the cold months.
Frost damage signs. Dark and slimy leaves in summer radishes; they form a little wilt in winter types, but revive. Dig down into the roots after a night's frost; if firm, you may dig and sell thin radishes if within twenty-four hours of a heavy frost, or within forty-eight hours of a light frost. I leave my winter clothes out until required for the table. A few light frosts improve the flavour.
The harvesting method differs in winter. I prefer to wait until midday, when the sun has thawed the soil sufficiently. I carefully twist the tough plants from the loosened earth. I would not dream of tearing or trampling on a frozen plant. To keep my harvest from freezing in transit, I wrap my insulated basket in a thick cloth. Above all, ensure that it is stored in a cool place immediately.
Read the full article: How to Grow Radishes: Foolproof Guide
