Can radishes survive frost conditions in gardens?
Written by
Nguyen Minh
Reviewed by
Prof. Martin Thorne, Ph.D.Radish frost tolerance is highly variable. Winter varieties, such as Daikon and Watermelon radishes, have excellent frost tolerance even with light frost. Spring varieties, such as Cherry Belle, can sustain damage when temperatures drop below 32°F (0°C). Daikon radishes have overwintered well under snow cover, yielding sweeter roots in the springtime.
Variety Differences
- Winter radishes tolerate temperatures down to 26°F (-3°C)
- Spring varieties sustain damage at 32°F (0°C)
- Watermelon radishes increase sugar content after frost exposure
- Daikon varieties develop thicker protective skins
Frost Effects
- Light frost converts starches to sugars enhancing sweetness
- Hard freeze causes cellular damage turning roots mushy
- Repeated frost-thaw cycles create cracking in roots
- Frost-killed leaves indicate root damage below ground
Protection Methods
- Cover spring varieties with row covers below 35°F (2°C)
- Apply 3-4 inch (8-10 cm) straw mulch around plant bases
- Use cloches for individual plants in unexpected frosts
- Water soil before frost events to moderate temperature drops
Harvesting after frost can be a tricky balancing act. Use them within 48 hours of getting first frost (even a light frost). To check them, gently probe into the soil to see if the roots are firm or not. To conduct a test on a radish, cut it open and inspect the flesh. If it's mushy, water-soaked, or gelatinous, you've had a freeze. Most of the time, though, you'll be fine. I harvest winter varieties immediately after a light frost to achieve the best flavor.
Protect your spring radish crop easily. Put up hoop houses prior to the first frost in fall. Use floating row covers held down by soil pins. Another option is to add thermal mass: use water jugs or pitchers and paint them black. These seasons will allow you to keep harvesting for 2-3 weeks longer in my Zone 5 garden.
Plan your planting for frost tolerance. Plant winter varieties 8-10 weeks before your first frost date. Using a sheltered south-facing bed. Use compost to improve soil drainage and prevent freezing. I plant radishes with frost-hardy kale for additional protection for both.
Read the full article: 3 Signs to Know When to Harvest Radishes
