Pruning Blackberries

Pruning blackberries sounds fiddly, but it comes down to one yearly cut. Once you understand which canes do the work, the job takes minutes and keeps your plant cropping well for years. This guide is part of our full blackberry growing guide.

The simple rule

Blackberries fruit on canes that grew the previous year. A cane spends its first summer growing long and green, fruits the following summer, then dies off — it never fruits twice.

So at any time your plant has two kinds of cane:

• This year's new canes — fresh, green, often growing from the base. These fruit next year. Keep them.
• Last year's canes — older, darker, woodier. These are the ones carrying fruit now, and they'll die after harvest. Cut them out.

Get this distinction right and pruning is easy. The whole job is just removing the spent old canes and looking after the new ones.

When and how to prune

Prune after fruiting, in late summer or autumn once you've picked the last berries — usually September into October in most of the UK. There's no winter pruning needed (unlike apples and pears), and certainly no summer pruning the way you'd treat plums or cherries.

Here's the method:

1. Pick out the fruited canes. They're the darker, woodier ones that just carried berries. Trace each back to ground level.
2. Cut them right down to the base. Use clean, sharp secateurs or loppers and cut as low as you can — there's no need to leave a stub.
3. Pull the cut canes out of the support wires. Dead, thorny canes tangle badly, so removing them now saves grief later.
4. Keep every healthy new cane for next year (you'll thin and tie these in next).

That's the core of it. The plant looks much tidier straight away, and all its energy goes into next year's wood.

Thinning the new canes

A healthy plant throws up far more new canes than it needs. Leaving them all gives you a congested, disease-prone tangle that's miserable to pick from. Thinning fixes that.

Keep around 6 to 8 of the strongest new canes per plant and cut the rest out at the base. Choose sturdy, well-placed canes and remove anything thin, damaged or growing in an awkward direction.

Then tie the keepers in to your wires, spacing them evenly. Good spacing means better air flow, riper fruit and far easier picking. This is exactly where it pays to have a proper support system — our guide to training blackberries walks through the wires and the tidiest training methods, like keeping new canes to one side while the old ones fruit on the other.

If your canes have grown very long, you can tip-prune them in late winter, trimming the ends back to healthy buds. This encourages side shoots and keeps the plant within its space.

Taming an overgrown plant

Inherited a thorny thicket? Don't panic — blackberries are tough and respond well to a hard reset.

Work through it in stages:

1. Cut out all the old, dead and dark fruited canes to the ground. On a neglected plant this is most of the mess, and clearing it reveals what you're working with.
2. Identify the live new canes — green, flexible, this year's growth.
3. Thin hard. Keep only the 6 to 8 best, evenly spaced, and remove everything else at the base.
4. Tie the keepers in to a fence or wires so the plant has shape going forward.

A plant that's been wild for years may sulk for a season, but it'll reward you with a far better, cleaner crop the following summer. If it's hopelessly congested and unproductive, cutting the whole thing to the ground in autumn is a valid last resort — you'll lose next year's fruit but get strong fresh canes to train properly.

Once you've reset an overgrown plant and trained it well, keeping it in order is just that one annual cut. For the full picture — choosing varieties, planting, feeding and picking — head back to the blackberry growing guide, and browse more soft fruit in our grow fruit hub.