The Freeze Tolerance of Raspberry Vines

Summer-Bearing Raspberries

• Summer-bearing raspberries produce fruit on 1-year-old canes. If the canes are damaged during the winter, the fruit crop will be reduced or eliminated. Most summer-bearing varieties are hardy to 15 degrees below zero Fahrenheit. Consult a county extension agent for varieties adapted to your area. Boyne, Latham and Killarny are three very cold-hardy cultivars to try.

Everbearing Varieties

• Everbearing raspberries produce fruit on 1-year-old canes in early summer, followed by a second crop grown on new canes in the fall. These varieties are suitable for areas with late spring frosts because if the old canes sustain winter damage, the new canes still produce a fall harvest. Many gardeners prefer to mow the canes down every fall, maintaining a fall harvest only. Select an early ripening variety, such as Polana or Autumn Bliss, if you live in an area prone to early frosts.

Growing Conditions

• Growing conditions may also influence a raspberry plant's ability to tolerate freeze. Plant raspberries on a sunny slope, protected from heavy winds. Avoid low areas where frost pockets tend to linger. Reduce water in late summer or early fall to prepare the plants for dormancy, and don't fertilize after midsummer. Late-summer fertilizing encourages new growth, prone to winter damage.

Winter Protection

• Mulch all raspberries with straw or untreated, dried grass clippings in the summer. This practice conserves moisture and reduces weed growth during the summer and provides insulation during the winter. In late fall, bend summer-bearing canes down to the soil. Place a shovelful of soil over them to hold them in place. Dig soil from either side of the plants to cover the canes completely with 2 to 3 inches of soil. Remove the soil in the spring before new growth emerges. This practice is not necessary for everbearing raspberries, and is only necessary in areas with very cold winters. Hardy varieties, such as Boyne and Nova, don't need covering.