Trellis System for Raspberry and Blackberry

Why does the trellis system matter so much?

Raspberry and blackberry produce long, flexible canes. Left without support, those canes tangle, lie down on the ground and disrupt both light interception and air circulation within the row. A trellis system holds the canes in a set order so every plant gets enough sunlight through the day, keeps air moving inside the plant structure, and improves access to the canes at harvest.

In our field work we see disease pressure and harvest losses running clearly higher in orchards with no trellis or an inadequate one. Fungal diseases in particular spread far more easily in a humid, closed cane environment; unsupported canes get crushed and damaged at harvest and shelf life shortens. We therefore treat the trellis not as “an extra cost” but as the load-bearing infrastructure of the crop.

A few basic decisions must be made before the system goes up: row orientation, post type and spacing, wire count and layout. All of these should be planned in advance at orchard establishment; changing them after planting is both difficult and expensive.

Which training system is used for raspberry and blackberry?

The main training systems used in berries fall into three groups: single wire (single row), double wire (V or T system) and the cage or cross-wire system. The choice is shaped by plant type (erect or trailing canes), orchard size, mechanisation needs and the grower’s harvest method.

Single row system: canes are held tied to a single row of wire. It is the simplest to install and the lowest in initial cost. It suits narrow row spacing or small hand-harvested orchards. In high-yielding varieties, however, managing cane crowding becomes harder and light interception can be limited.

T or double wire system: two wires are placed parallel or at a slight angle so the canes spread to both sides. Light interception and air circulation improve markedly over the single row, and access at harvest is easy from either side. In our field observations this system gives the most balanced result in medium and large-scale raspberry production.

Cage or free-growth system: particularly suited to the long, trailing canes of blackberry, this structure lets canes grow held between several horizontal wires. It takes a little more care to manage, but works well in high-density blackberry orchards, where fruit gets sun instead of sitting in shade.

How are post type and spacing decided?

The job of the posts is to carry the whole load of the system: the weight of the wire, the tying material and, above all in the cropping period, the total weight of canes laden with fruit. That load can be heavier than first estimated, so durability should be the primary criterion in choosing posts.

Concrete posts: the longest-lived option. Installation cost is higher than the alternatives, but maintenance is close to zero. For large orchards planning a long-term investment they become the more economical solution over time.

Wooden posts: hardwoods such as oak and beech, or treated pine, are preferred. They are a balanced option for ease of installation and initial cost. However, the buried section carries a risk of moisture-driven rot; that zone must be pressure treated or coated. The life of wood is shorter than that of concrete.

Galvanised or metal posts: durable and relatively easy to install. They can be preferred at the corners and end points of the row in particular. Using metal along the whole row can weigh heavier on cost than concrete or wood.

Post spacing varies with row length, wire count, soil firmness and post type. In general practice a spacing of 4 to 8 metres is observed; it is shortened on long rows carrying heavy loads and can be lengthened on short rows. These are not a fixed standard but typical ranges to be adjusted by region, variety and load calculation.

Corner and end posts take the greatest pull load, so they should be chosen stronger and must be cross-braced. Left weak, these points become the first link that unbalances the whole system.

At what heights are the wires placed?

Wire count and height are decided by the training system used, the average cane height of the variety and ease of harvest. The most common practice is to use two to four wire rows; the number and heights vary by variety and system.

• Bottom wire (first row): typically positioned 60-80 cm from the ground. It holds the base of the canes, prevents them lying down and helps air circulate at the base of the row.
• Middle wire (second row): can sit at roughly 100-130 cm. It is the main support line; canes are tied most densely at this level and this wire carries much of the system load.
• Top wire (third and fourth rows): used in tall varieties and in T system installations. A height of 150-180 cm is taken as typical, varying with the cane height of the variety.

These heights are reference ranges and must be adapted to your variety, harvest method and chosen system. Where a harvester will be used in particular, the row spacing and working height the machine requires determine the system directly, and those requirements should be built into the plan from the start.

Galvanised steel wire is widely used as the wire material. Thin wire stretches and sags over time, so gauge should be chosen to suit row length and load. Stainless wire lasts longer but costs more. In protected or soilless systems, plastic or PVC-coated wires can be preferred.

How is row orientation chosen?

Row orientation directly affects light interception efficiency, air circulation and exposure to the prevailing wind. The general rule of practice is to run rows north to south. In that orientation both sides of the row receive morning and afternoon sun evenly, and shading is minimised.

On sloping land, running rows across the slope may be preferred for erosion control. Some light interception is given up in that case, but the risk of soil and water loss falls. The two factors should be weighed against each other.

Where the prevailing wind is strong, positioning rows parallel to it reduces the lateral load on the canes. But how that choice affects light interception must also be considered. On open land with no windbreak trees or hedges, making corner and end posts especially strong and braced is essential.

Row spacing varies with harvest method and variety. A narrower working gap is enough in small hand-harvested orchards, while holdings planning machine harvest must allow the width the machine requires. Making that decision before the orchard is established avoids the cost of rearranging later.

What mistakes are made during installation?

From years of field observation, the installation mistakes we meet most often can be summarised as follows.

Building end and corner posts inadequately: these points take the greatest pull load, and if built weak they bend over time and the tension of the whole system is lost. End posts should be braced, or a stronger post type chosen than for the rest.

Not setting wire tension correctly from the start: loose wire swings, fails to hold the canes properly and sags further over time. Using an in-line strainer makes adjustment after installation easy; leaving that piece of equipment out creates more labour in the long run.

Not burying posts deep enough: in loose or wet soils in particular, shallow setting leads to posts going over under wind or load. As a general rule, burial depth is kept between a quarter and a third of the post length, and increased according to soil structure.

Trying to build the system after planting: driving posts and tensioning wire once the plants are in damages roots and seriously disrupts ergonomics. The trellis should be completed before planting, or at the latest at the same time.

Keeping the wire count too low: in high-yielding varieties especially, a single wire falls short; canes scatter into the row, harvest becomes harder and light interception suffers. Building the system a little more thoroughly at the outset avoids extra intervention in later years.

How do we keep the system sound for years?

A trellis system, built correctly, can have a working life of more than ten years, and a few routine checks decide that life.

Start-of-season general maintenance: after winter pruning and before new canes emerge, all posts, wire tension and connections should be reviewed. Loosened wires should be tensioned and leaning posts straightened rather than left to the next season.

Renewing the tying material: the loop ties, cable ties or purpose-made tying tape used to fix canes to the wires break over time, or harden and damage the cane. Old ties should be checked at the start of the season and replaced where needed.

Post bases and wire attachment points: the buried section on wooden posts, and welds and joints on metal posts, weaken over time. Problems noticed before visible deterioration are solved by attending to a single post; neglected, the collapse of a whole row creates far more work and cost.

Fitting with pruning and cane management: the trellis should be thought of as one whole with pruning and cane thinning. Leaving too many canes raises the load the system must carry, which works against both wire tension and post stability. Regular thinning and tying protect the life of the system while supporting plant growth and yield.

Other subjects around establishing a berry orchard — from variety choice to irrigation infrastructure — are covered on the berries hub page. Once the trellis is up, the berry fertilization article is a good companion for managing plant nutrition correctly, because well-fed canes use the system more evenly and harvest quality rises.

A properly built trellis is not an investment that keeps making itself felt in the field; it works quietly, gives the plant order, and delivers a more accessible, more productive orchard at every harvest.