Blackberry (Rubus species) plants are highly productive cane fruits that require regular pruning to maintain vigor and maximize fruit yield. This necessary cultural practice directly impacts the plant’s health and productivity. Routine removal of old growth focuses the plant’s energy into producing new, strong canes that will bear the next season’s crop. Pruning also improves air circulation within the dense canopy, which helps control common fungal diseases. Without proper management, blackberry patches quickly become tangled, unproductive thickets that are difficult to harvest and prone to pests.
The Blackberry Life Cycle: Primocanes and Floricanes
Understanding the two types of canes is the foundation for successful blackberry pruning. While the plant’s root crown is perennial, its individual canes are biennial, meaning they live for two years. First-year canes are called primocanes; their role is purely vegetative, focusing on growth and establishing a strong structure. These new shoots emerge each spring and grow vigorously throughout the season, but they do not typically produce fruit on floricane-fruiting varieties.
As the plant enters dormancy, the primocane overwinters and becomes a floricane in its second year. Floricanes develop lateral branches in the spring, flower, and subsequently produce the summer fruit crop. Once the floricane has finished fruiting, its life cycle is complete, and the cane will begin to die back naturally.
This biennial pattern means an established blackberry patch always contains two generations of canes simultaneously. Each year, new primocanes emerge to replace the floricanes that are fruiting and dying. The goal of pruning is to remove the spent floricanes to make room for the developing primocanes, which will become next year’s fruit-bearers.
Dormant Season Pruning: Structural Cuts and Cane Removal
The most significant pruning occurs during the dormant season, typically in late winter or early spring before the buds begin to swell. The first step is to identify and completely remove all canes that fruited the previous year (the dead floricanes). These canes will be woody, gray, or brown, lacking any sign of new growth, and should be cut back to the ground level. Removing this spent wood eliminates potential overwintering sites for pests and diseases.
Once the dead floricanes are gone, attention shifts to the remaining primocanes, which will fruit in the coming season. These canes must be thinned to prevent overcrowding, improving light penetration and air movement, which leads to larger, higher-quality fruit. For erect and semi-erect varieties, leave only four to six of the strongest, pencil-thick canes per linear foot of row. Cut any weaker or excess primocanes off at the soil line to direct the plant’s energy into the most vigorous remaining shoots.
The remaining primocanes should then be headed back to control their height and promote lateral branching. Canes that have grown excessively tall should be topped, or cut back, to a manageable height of approximately five to six feet. This heading cut stops vertical growth and stimulates the growth of side branches lower down.
The newly encouraged lateral branches, which will bear the fruit, also need to be shortened during the dormant prune. The laterals should be cut back to a length of 12 to 18 inches, ensuring that five to six healthy buds remain on each branch. This process concentrates the plant’s resources to fewer fruiting sites, resulting in larger, more uniform berries and a bush that can better support the heavy fruit load.
Summer Pruning and Training: Managing New Growth
Summer pruning occurs while the plant is actively growing, focusing on shaping the new primocanes to maximize fruiting sites for the following year. This process begins in late spring or early summer when new primocanes of erect and semi-erect varieties reach a height of three to four feet. At this point, the growing tip of the cane is removed, a practice known as “tipping” or “pinching.”
Tipping involves snapping off or cutting the top few inches of the tender, non-woody new growth. This heading cut interrupts the flow of growth hormones, forcing the cane to develop strong, productive lateral branches. If tipping is skipped, the cane continues to grow straight up, resulting in a single, tall cane with fewer potential fruit-bearing sites.
As the growing season progresses, the new lateral branches that emerge from the tipped primocanes may require minor trimming if they become excessively long. This secondary tipping helps maintain a compact, controlled growth habit and encourages denser fruiting wood.
Training the canes is another summer task, especially for semi-erect varieties that benefit from support. New primocanes should be loosely secured to a trellis or support system to keep them off the ground, which prevents disease and makes subsequent pruning and harvesting easier. Additionally, suckers—new shoots that emerge from the roots outside the desired row—should be pulled or cut out at ground level to keep the patch contained.