Do Blackberries Need a Trellis? | It Depends on the Variety

Whether blackberries need a trellis depends entirely on the type you plant; trailing and semierect varieties require support, while erect varieties can grow without one if pruned correctly.

Many home gardeners assume all blackberry bushes need a trellis, but that depends on which cultivar you choose. Erect blackberries like ‘Apache’ or ‘Arapaho’ grow stiff, self-supporting canes that hold fruit without any structure. Trailing and semierect blackberries produce long, flexible canes that flop to the ground under their own weight once they fruit. A trellis keeps the fruiting wood upright for better sun exposure, easier picking, and healthier plants. Here is how to decide which system you need and how to build it.

Which Blackberry Varieties Require a Trellis?

Trailing and semierect cultivars must be trellised; erect cultivars can grow without one if pruned properly. Trailing blackberries produce thin, arching canes that cannot support themselves as they grow, so a simple two-wire trellis is mandatory. Semierect varieties are slightly stiffer but still need a sturdy support system — typically a “Double T” trellis. Erect blackberries, when pruned correctly (primocane tipping and cane thinning), stand upright on their own.

The table below summarizes the trellis requirements for each type:

If you already have a mix of types on your property, or you want a structure that looks great in the landscape, our roundup of the best decorative blackberry trellises covers attractive options that work with any variety.

How To Build a Blackberry Trellis for Trailing Varieties

Trailing blackberries need a sturdy two-wire trellis to keep the heavy canes off the ground. The system uses end posts, intermediate T-posts, and two parallel wires running the length of the row.

• End posts: Set treated wooden or metal posts 6 feet above ground, 3–4 inches in diameter.
• Intermediate posts: Metal T-style posts every 15–20 feet in the row.
• Wire: Run a single wire down each side of the row. Use gauges 10–16.
• Wire heights (two-wire): Lower wire at about 36 inches, upper wire at about 60 inches.

Install separate wire stretches between posts rather than one continuous length — this prevents sagging under the weight of fruit. Allow a 6-inch overlap at each screw head, then twist the wire back on itself and wrap it around the screw.

How To Build a Trellis for Semierect Blackberries

Semierect varieties require a Double T trellis because the canes are heavier and need a wider support frame. This design uses a T-shaped crosspiece at each post to hold two wires on each side of the row.

• Posts: Install robust wooden posts at closer spacing than trailing systems.
• Crosspiece: Attach a horizontal 1.5-foot rebar or wood crossbar at each post.
• Wiring: String twine or wire down each side of the crosspiece to create four contact points per spacing.

This wider spread keeps the vigorous semierect canes from piling up in a single wire. Oregon State University’s research specifically recommends this layout for varieties in that growth category.

How To Tie Canes to the Trellis Without Damaging Them

Tie canes during the dormant season after cutting back old wood, using a figure-8 loop to prevent wire rub. Dormant tying avoids snapping green, brittle canes and gives you clear access to the structure.

• Figure-8 method: Wrap garden string around the wire once, then around the cane once, creating a figure-8 that stops the wire from rubbing through the bark.
• Where to tie: Fasten the string where the cane is slightly brown and woody — tying around green, brittle sections causes breakage.
• Timing: Tie right after cutting out the floricanes (the old canes that just fruited).

This technique keeps each cane neatly spaced for airflow and light, reducing disease pressure compared to a tangled mass on the ground.

Do Erect Blackberries Need Any Support at All?

Erect blackberries do not require a trellis if you prune them correctly — but a one-wire system helps if you skip pruning. Erect cultivars like ‘Apache’ produce stiff canes that hold themselves upright, especially after you tip the primocanes at 15 inches to encourage branching.

If you leave erect blackberries unpruned, the canes grow tall and may tip over when loaded with fruit. A single wire strung 30–48 inches off the ground along the row gives those wayward canes something to lean on without the full cost of a two-wire system. You can also train them to a T-trellis with a 1.5-foot crosspiece, but this is purely optional.

Common Trellis Mistakes and How To Fix Them

Gardeners often use too-shallow posts, sagging wire, or excessive fertilizer — all of which hurt the plant more than help. Here is what to avoid:

• Posts less than 2 feet deep: End posts need at least 2 feet in the ground (some sources say 1 foot minimum, but 2 feet is safer for heavy fruit loads).
• One continuous wire length: Stringing wire from end to end without separate stretches causes sagging in the middle. Run a fresh length between each post.
• Over-fertilizing with nitrogen: Excessive nitrogen pushes soft, fast growth that is more disease-prone and harder to manage on the trellis.

For the end posts, drive a half-stake into the ground at a 45-degree angle, then run a wire from the stake to the top of the post. This anchor prevents the post from bending when the trellis is loaded with ripe fruit.

Final Checklist: What To Build for Your Blackberry Type

Match your trellis to the blackberry variety you are planting: trailing needs two wires, semierect needs double T, and erect needs nothing unless you prefer a single wire. Use this quick decision guide before you buy materials:

• Trailing blackberries: Build the two-wire trellis with end posts 6 feet tall and T-posts every 15–20 feet.
• Semierect blackberries: Install the Double T system for better cane spread and airflow.
• Erect blackberries (pruned): Save your money — no trellis required. Tip canes at 15 inches and thin to 6–8 per 3-foot row.
• Erect blackberries (unpruned): A single wire at 30–48 inches keeps them from flopping under heavy fruit.