Why Are My Blackberry Canes Damaged After Winter?

Blackberries are generally hardy plants — most established varieties tolerate typical UK winters without significant damage. However, an unusually cold winter, a severe frost period, or a combination of wet soil and hard frost can damage or kill canes that would normally survive. Newly planted blackberries and tender thornless varieties are most vulnerable. The damage typically shows as brown, shrivelled cane tissue, split bark, or completely dead canes that fail to produce any new growth in spring.

Assessing the damage in spring

In March, before the new growing season is fully underway, scratch the surface of each cane lightly with a thumbnail or knife. The tissue immediately under the bark (the cambium layer) should be green in a living cane. Brown or cream-coloured tissue under the bark indicates that section is dead. Work down from the tip of the cane until you reach a point where the underlying tissue is still green — cut back to this point, making a clean cut just above a bud. If the entire cane is dead to the base, cut it out at ground level.

Recovery

A plant that has lost most of its overwintered canes to frost will produce new primocanes from the crown and root system in spring and summer — blackberries are very vigorous at the root level even when canes are damaged. These new canes will not fruit in their first year but will carry the following season's crop. Recovery is usually full within one growing season unless the root system itself is damaged.

Protection for future winters

In areas with severe winters, new primocanes can be insulated by wrapping the tied canes loosely with horticultural fleece in November and removing it in March. For tender thornless varieties in very cold gardens, the canes can be untied from their support in autumn, laid down on the ground, and covered with a thick straw mulch — the insulation of the straw and soil significantly reduces the likelihood of frost damage to the cane tissue.