Confusion often arises because blackberries appear to climb structures in commercial settings, similar to traditional vines. Understanding the basic botany of the blackberry plant, a member of the Rubus genus, clarifies this distinction. The plant’s natural growth habits and biennial life cycle define its structure, which differs significantly from the climbing mechanism of a true vine.
The Definitive Answer: Canes, Not Vines
Blackberries are technically shrubs, often categorized as “brambles,” that produce woody, biennial stems known as canes. A cane refers to the hard, woody, and typically thorny stalk growing from the plant’s perennial crown and root system. This structure fundamentally separates blackberries from true vines.
The cane has a two-year life cycle. In its first year, the stem is a primocane, which grows vigorously and establishes the plant’s structure. In the second year, it becomes a floricane, producing flowers and fruit before dying back after harvest. True vines require external support to climb, often using specialized structures like tendrils or twining stems, none of which blackberries possess.
Understanding Blackberry Growth Habits
Blackberries are classified into three distinct types based on the natural tendency of their canes. This classification dictates how the plant behaves without human intervention.
Erect Blackberries
Erect blackberries have stiff, upright canes that are largely self-supporting and grow in a shrub-like manner. Varieties such as ‘Navaho’ require minimal structural support to remain upright.
Semi-Erect Blackberries
This type produces vigorous, thick canes that naturally arch as they grow. Although stronger than trailing types, these arching canes benefit from support to prevent sprawling under a heavy fruit load.
Trailing Blackberries
Trailing blackberries most closely mimic the appearance of a vine, as their canes are not stiff and naturally sprawl along the ground. This group includes plants like dewberries, which must be lifted off the ground for cultivation. Despite their sprawling habit, these stems remain canes because they lack the botanical structures needed to climb autonomously.
Why They Look Like Vines: The Role of Trellising
The widespread use of trellising in commercial production is the main reason blackberries are mistaken for vines. Growers use posts, wires, and other structures to train the canes vertically, particularly for semi-erect and trailing varieties. This is a management technique designed to optimize the plant’s production and health, rather than accommodating a natural climbing ability.
Trellising provides a structured support system that keeps the fruit off the ground, significantly reducing disease risk and making harvesting more efficient. Supporting the canes also increases airflow and ensures better sunlight exposure to the leaves and developing fruit. For example, a two-wire system is commonly used to manage arching or sprawling canes.
Growers must physically tie the blackberry canes to the trellis wires as they grow, confirming that the plant is supported by human action, not climbing autonomously. Although this trained, vertical growth resembles true vine cultivation, the blackberry remains a shrub that produces woody canes. Even naturally self-supporting erect varieties are sometimes trellised to manage height or prevent wind damage.