Supporting blackberry canes dramatically improves the plant’s health and productivity. A sturdy support system prevents the long, flexible canes from sprawling onto the ground, which keeps the fruit clean and reduces the chance of soil-borne diseases. Upright canes increase air circulation throughout the plant canopy, which is a natural defense against fungal issues. Furthermore, training the canes simplifies the annual pruning process and makes harvesting significantly easier by keeping the berries within easy reach.
Establishing the Support Structure
The first step in maximizing blackberry growth involves building a permanent structure to manage the canes. The best support system depends on the blackberry’s natural growth habit: trailing, semi-erect, or erect. Trailing and semi-erect varieties absolutely require trellising to prevent their long, arching canes from rooting where they touch the soil. A simple two-wire vertical trellis, often called an I-trellis, is a common and effective system for most home gardeners.
This basic structure requires sturdy posts, such as treated wood or metal T-posts, set at least 18 inches deep to withstand the weight of a mature, fruiting bush. The posts should extend about six feet above the ground and be spaced approximately 15 to 20 feet apart down the row. High-tensile, 12-gauge wire is then strung horizontally between the posts to create the support lines. A typical setup uses a lower wire around 30 to 36 inches from the ground and a second wire at the five to six-foot level.
For semi-erect cultivars, a Double T-trellis can be used to manage the vigorous lateral growth by providing four parallel wires. This system uses cross-arms attached to the main posts, which helps to separate the fruiting canes from the new growth for easier management. Alternatively, the V-trellis utilizes two pairs of wires angled outward from the top of the post to create a V-shape. The V-trellis is particularly effective at maximizing sunlight exposure and improving airflow. This infrastructure must be established before the active growing season begins for successful training and tying.
Pruning and Cane Selection
Successful tying requires understanding the two-year life cycle of the blackberry cane, differentiating between primocanes and floricanes. Primocanes are the first-year canes, characterized by their thicker, greener, and more fleshy appearance, and they do not produce fruit. These canes typically exhibit longer spaces between leaf nodes and their compound leaves often have five distinct leaflets.
As the primocane overwinters, it transitions into a floricane in its second year, becoming woodier and often turning a brown or purplish-brown color. The floricane is the fruiting wood, producing blossoms and berries in the early to mid-summer. Floricanes are distinguishable by their shorter internodes and compound leaves with only three leaflets.
Pruning is an annual necessity completed before the tying process begins. Immediately after the summer harvest, all floricanes must be cut out completely, as they have finished their life cycle. Removing this spent wood directs the plant’s energy toward the new primocanes and improves air circulation, which helps prevent disease.
Proper summer pruning involves tipping the new primocanes when they reach 3 to 4 feet, encouraging the growth of lateral branches. These laterals bear the fruit the following year and should be pruned back to 12 to 18 inches during the dormant winter period.
Step-by-Step Guide to Tying Canes
Once the old floricanes have been removed and the new primocanes have been selected and pruned, the physical act of securing the healthy canes to the trellis begins. The best materials for this task include biodegradable jute twine, flexible plastic clips, or expandable vinyl tape. Using an expandable material like vinyl tape is recommended because it prevents the tie from girdling or cutting into the cane as the cane thickens over the growing season.
For a two-wire vertical trellis, the goal is to align the selected primocanes neatly along the wire structure. Canes can be gently woven horizontally along the wires, or individual canes can be secured directly to the wires with ties. When tying, it is important to loop the material loosely around the cane and the wire, ensuring the cane is not cinched tightly against the support structure. This slack allows the cane to grow in diameter and shift slightly with the wind without being damaged.
If managing a large number of canes, a common technique is to train the new primocanes along one side of the trellis and the floricanes along the other. This separation makes the next year’s pruning and harvesting easier. Training the canes in a fan shape or weaving them horizontally maximizes the exposure of leaves and developing fruit to sunlight. Maximizing sunlight is necessary for optimal ripening and sugar development. Consistent tying and training throughout the growing season ensures that the weight of the fruit is supported and the bush maintains an open, productive structure.