Blackberries are perennial plants, meaning their roots and crown live for many years, but their above-ground structures operate on a distinct two-year cycle. They are often mistakenly called bushes, but the structure that supports the leaves, flowers, and fruit is a specialized stem called a cane. Blackberries produce an aggregate fruit composed of multiple small drupelets. Understanding this cane growth is the first step in properly identifying and managing the plant.
Defining the Growth Habit
Blackberries belong to the Rubus genus, characterized by unique biennial stem growth. The plant produces two types of canes, each with a specific role in the life cycle. First-year stems are known as primocanes; their growth is purely vegetative, focusing on storing energy and developing strong roots. Primocanes are generally green and flexible, but they do not produce flowers or fruit during their initial season.
During the dormant winter period, primocanes harden and convert into second-year canes called floricanes. Floricanes are the structures that produce the flowers and subsequently the harvestable fruit. Once the floricane has yielded fruit, its life cycle is complete, and it naturally dies back. This continuous cycle involves new primocanes emerging annually while the floricanes are simultaneously fruiting.
Types of Blackberry Growth
Blackberry varieties are categorized into three types based on their physical growth habit, which dictates how the plant will grow and the support it requires. Erect varieties have stiff, self-supporting canes that stand upright. These types often spread by producing new shoots, or suckers, from the roots, creating a dense hedgerow.
Semi-erect blackberries are vigorous growers, producing thick canes that start upright but then arch toward the ground as they lengthen. Due to this arching growth, semi-erect varieties typically require some form of trellising or support to keep the canes off the ground and maintain good air circulation.
Trailing or vining blackberries have canes that are the least rigid and cannot support their own weight. These types must be attached to a trellis or wires to grow vertically, maximizing sun exposure and making harvesting easier.
Essential Care for Cane Management
The biennial nature of blackberry canes requires specific pruning techniques for optimal production and health. Spent floricanes, which have finished fruiting, must be removed entirely at ground level immediately after harvest. Removing these dead canes prevents disease spread and redirects the plant’s energy toward the new primocanes.
Managing the new primocanes is the other half of the pruning process. For many varieties, the tips are “tipped” or pinched off once they reach a height of about 3 to 4 feet in midsummer. This action encourages the cane to develop lateral branches, increasing the number of locations where fruit will be borne the following year. Trailing and semi-erect types benefit from a simple support system, such as T-posts with wires, which keeps the plant organized, improves light penetration, and simplifies harvesting.