Brambles

General Information

The success of a bramble planting is highly dependent upon its location. The site should have full exposure to sunlight and good air circulation. It should also be somewhat protected, however, as brambles are quite susceptible to winter injury. Temperatures below -20˚ F will injure most fruit buds above the snow line. Colder temperatures, especially if no snow cover is present, can kill canes to the ground, or damage roots, causing plants to die in the early summer when not enough water can be taken in to support them.

The soil should be well-drained; brambles will not tolerate “wet feet.” Wet soils encourage the spread of Phytophthora root rot which will destroy brambles. Do not plant brambles where potatoes, tomatoes, peppers, strawberries or eggplant have recently been grown, because these crops carry Verticillium, another root rot fungus which can infect brambles. Avoid planting brambles near any wild brambles. Wild raspberries and blackberries harbor insects and virus diseases which will spread to cultivated plants. If possible, destroy all wild brambles within at least 600 feet of your planting.

Always obtain raspberry plants from a reputable nursery which certifies their plants to be virus-free. Raspberries are best planted in the early spring. Plant your rows at least 8 feet apart, preferably 10 to 12 feet apart to ensure adequate air circulation, as well as room for spraying, harvesting and pruning operations.

Raspberry plants are shallow-rooted and thus are poor competitors for water and nutrients if weeds are present. A 3 to 6” layer of mulch will help to conserve soil moisture and inhibit weed growth. Coarse sawdust, wood chips or bark make good mulching materials. Pine needles work well, but need replenishing more frequently. Mulching of raspberry plantings is not without risk. The use of a permanent mulch may delay fruit ripening and plant hardening-off in the autumn, increasing the risk of winter damage. Mulching is not recommended after the first year on heavy soils due to the risk of Phytophthora. Mulch is also a haven for rodents that feed on plant roots and canes. Baiting is recommended where mulch is used.

Proper pruning is a crucial part of pest management for raspberries. In summer bearing brambles, remove second year canes and thin out weak, spindly first year canes anytime after harvest through winter. Thin out the remaining canes, leaving only those with good height, large cane diameters and no insect or disease damage. In late winter check for symptoms of winter injury. Everbearing varieties (e.g., Himbo Top, Anne) may be completely mowed down each year in late fall to early spring before growth starts. This will result in only the primocane (Fall) crop being harvested. For an early summer crop on everbearing varieties, remove weak, spindly first year canes after harvest and thin out remaining canes. Remove the tops of the canes where fruit was borne to reduce disease pathogen inoculum. The new fruit crop is borne on the cane below where fruit was the previous fall. 

Plant rows should be narrowed to a width of 2 feet or less. When finished, there should be no more than 4 to 6 canes per linear foot of row remaining for red raspberries, and 4 to 8 canes per crown for blackberries, black and purple raspberries. Canes which have been cut should be removed from the planting and destroyed. Pruning in this manner will greatly reduce the incidence of most raspberry cane diseases by increasing air circulation and reducing disease inoculum. Check with your Cooperative Extension office for details of proper varieties and cultural techniques for brambles, or see NRAES 35, Raspberry & Blackberry Production Guide available through New England Extension Fruit Specialists. See source page at end of this guide for more information on ordering the Raspberry & Blackberry Production Guide.