Cabbage holds up well in the cold better than most vegetables, but it has its limitations. Light frost improves its quality by transmuting starch into sugar. Still, if the plant is severely frozen, it is ruined, dead, tatters of vegetation in which the cells have been broken. If you are familiar with this boundary line, your harvest will not be lost in this instance.
Temperature Tolerance
- Light frost: 32-28°F (0 to -2°C) enhances sweetness
- Moderate freeze: 27-20°F (-3 to -7°C) causes minor damage
- Hard freeze: Below 20°F (-7°C) destroys cell structure
Plant Protection
- Cover plants with row covers when frost is forecast
- Use cloches for individual plants in extreme cold
- Mulch heavily around bases to insulate roots
Harvest Timing
- Pick before hard freezes if protection isn't possible
- Harvest after light frost for sweeter flavor
- Avoid harvesting frozen heads wait for thaw
Below 32°F (0°C), light frost exposure initiates sugar production positively in all types of cabbage. This process naturally produces more sugar in the plant, thereby resulting in "sweeter" heads when harvested. To achieve maximum sweetness, allow 2 to 3 light frosts before harvesting; however, the temperature drop from room temperature to freezing must be gradual and not abrupt.
When the temperature falls below 28°F (-2°C), all plants should be protected from the cold. Use lightweight row covers, secured at the edges with soil. During the day, when the temperature is above freezing, remove the row covers. For tender young plants, additional mulch should be applied to protect them from the elements. Do not place plastic over foliage.
Once frost damage has occurred, the heads should be assessed carefully. The outer leaves of the head may be slightly frozen, but they will still be edible once thawed. Heads with mushy textures or blackened cores should be discarded. To prevent future frost damage to your crop, consider planting cold-hardy varieties, such as January King.
To preserve them properly, frost-kissed cabbage should be kept in a cool place (32-40°F or 0-4°C) with high humidity. The extra sweetness from being frost-kissed lasts around 2 to 3 weeks, so use these heads first, as they will not last as long as cabbage that was not frost-kissed. Enjoy the different flavor experience as well.
Read the full article: 5 Key Signs: When to Harvest Cabbage
