Blackberries are vigorous, high-yielding brambles that benefit greatly from attentive management. Annual pruning is necessary to control the plant’s aggressive growth habit, improve air circulation to minimize disease risk, and maximize the quality and quantity of the fruit harvest. The timing of these cuts depends entirely on understanding the plant’s unique two-year growth cycle and identifying the variety being grown.
Understanding Blackberry Cane Cycles
The perennial crown of the blackberry plant produces canes that are biennial, meaning each individual cane lives for exactly two years. This two-year cycle dictates the pruning schedule. The two distinct types of canes are called primocanes and floricanes.
Primocanes are the first-year canes, characterized by green, vegetative growth that emerges from the ground each spring. These canes generally do not produce fruit in their first season, focusing instead on storing energy. When primocanes survive the winter and enter their second year, they are classified as floricanes.
Floricanes are the two-year-old canes that produce the summer fruit crop. After yielding berries, their life cycle is complete, and they die back. An established blackberry patch will always contain both primocanes and floricanes growing simultaneously, which means pruning requires identifying and selectively removing only the spent canes.
Pruning Timing for Floricane-Fruiting Varieties
Floricane-fruiting varieties, often called summer-bearing, produce fruit exclusively on the second-year canes. Managing these plants involves a two-part annual pruning strategy: one immediately after harvest and a second during the dormant season. This method ensures that the plant directs energy efficiently toward the next season’s crop.
Post-harvest pruning occurs in the summer or early fall, immediately after the berries have been picked. This involves cutting all the spent floricanes down to the ground level for sanitation. Removing these dead canes reduces the risk of disease and pest buildup, while also opening the canopy to allow more air and light to reach the new primocanes.
The second pruning phase happens during the dormant season, typically in late winter or early spring before new growth begins. During this time, the remaining healthy primocanes, which will become next season’s floricanes, should be managed for structure and yield. Weak, thin, or damaged primocanes should be removed, leaving only the strongest three to eight canes per plant.
This late-winter pruning also involves heading back the remaining canes and shortening their lateral branches. The main canes are cut back to a manageable height of about 3.5 to 4 feet, or just above the top trellis wire. Trimming the side branches, or laterals, to a length of 12 to 18 inches encourages the production of more fruiting buds along the cane in the spring.
Pruning Timing for Primocane-Fruiting Varieties
Primocane-fruiting blackberries, sometimes called fall-bearing or everbearing varieties, produce fruit on the tips of the first-year canes in late summer or fall. This allows for two distinct pruning options, giving the grower flexibility in managing the harvest schedule: pruning for a single, large fall crop or for a smaller summer and fall crop.
For a single, large fall crop, the simplest approach is to cut every single cane down to the ground in late winter or early spring. This removal should be done before new growth starts, effectively eliminating all potential floricanes. The new primocanes that emerge will then produce a single, substantial harvest at their tips later that same year.
The alternative method is managing the plant for two crops: a fall crop on the primocanes and a summer crop on the floricanes the following year. After the fall harvest is complete, only the portion of the cane that produced fruit is tipped back, leaving the lower cane intact. The remaining cane will then mature into a floricane, which will fruit lower down the cane in the early summer before it is removed completely.
Essential Tools and Techniques for Effective Pruning
Tools and Sanitation
Sharp bypass hand pruners are suitable for thinning smaller canes and lateral branches, while long-handled loppers are necessary for cutting the thicker, woody floricanes down to the ground. Wearing heavy-duty leather gloves and long sleeves is recommended to protect against thorns, even on thornless varieties.
Tool sanitation is important to prevent the spread of fungal diseases between plants. Pruning tools should be cleaned and disinfected before starting and after pruning each plant. All removed cane material, especially any that appears diseased, must be promptly removed from the planting area and destroyed to eliminate potential sources of infection.
Tipping and Thinning Techniques
Tipping, or heading back, is performed on primocanes during the summer growing season to encourage branching. When a new primocane reaches a height of 3 to 4 feet, the top two to four inches of the tender growth should be pinched off or cut. This removal of the terminal bud releases the plant’s apical dominance, stimulating lateral branches to grow, which increases the surface area for the next season’s fruit production.
Thinning is another important technique, regardless of the fruiting type, and is done to manage cane density. The removal of weak, spindly, or crossing canes ensures that the plant has adequate air circulation and light penetration, resulting in larger, better-quality fruit. Canes should be cut as close to the soil surface as possible to prevent leaving small stubs that can harbor pests or diseases.