Can kale survive freezing winter temperatures?
Written by
Olivia Mitchell
Reviewed by
Prof. Samuel Fitzgerald, Ph.D.Mature kale plants show remarkable winter hardiness, surviving temperatures down to 20°F (-7°C) with minimal protection. Cold-tolerant types like'Winterbor' can survive even more extreme temperatures with proper mulching. Gardeners in zones 7 and above often harvest fresh kale through the winter by using simple frost covers. Success relies on the plants being mature before the first frost and protecting them with a specific frost cover.
Mulching Techniques
- Material depth: Apply 6-8 inch straw layer around plant base
- Timing: Mulch after first hard frost but before ground freeze
- Coverage: Extend 12 inches beyond plant drip line
- Material choice: Straw outperforms leaves for insulation
Frost Protection
- Row covers: Use 1.5 oz fabric when below 25°F (-4°C)
- Cold frames: Install for continuous harvests below 20°F
- Cloche options: Repurpose milk jugs for individual plants
- Ventilation: Open covers during sunny winter days
Make plants winter resilient with good fall care. Harden off plants by reducing watering for 6 weeks before the first frost. Apply balanced fertilizer early in the fall to reinforce the cell walls. I also wrap the stem with burlap in zone 5 for wind protection. Lastly, refrain from pruning back after September to prevent frost damage.
Identifying and Addressing Winter Damage Indicators Quickly: Leaves that are purple-black signify extreme cold stress. Stems that are mushy indicate crown rot due to ice. Frost-burn leaves look semi-translucent. I will panic-spray plants with seaweed extract to assist in recovery. If any harvest is feasible after damage takes place, harvest as much as possible to salvage edible parts only.
Read the full article: When to Plant Kale for Optimal Growth
