Pruning Blackberry
When and how — Rubus fruticosus
Prune your blackberry in August and September — the optimal month is usually September.
The next pruning window is August.
When to prune?
The fruit blackberry is pruned in August and September.
Pruning fruit is about balancing growth and yield.
Fruit trees and bush fruits live in an eternal balance between leaf production (vigour) and fruit (yield). Prune too little and you get a dense plant with masses of small, disease-prone fruit. Prune too much and the plant reacts with watershoots and almost no fruit. The right line: once a year in winter dormancy (January–February) shape an open crown so light and air can reach every branch. With apple and pear, learn the difference between fruit spurs (short, 2–3-year-old wood — that's where the flowers come from) and wood buds (long whippy growth). Bush fruits need a different approach: redcurrant and gooseberry are pruned to an open goblet shape; blackcurrant needs renewal pruning where you remove one-third of the oldest stems at ground level each year.
How to prune blackberry
Blackberries fruit on canes produced the previous year, so pruning is essential to keep plants productive and manageable. Prune in August or September, immediately after you've finished harvesting. This timing allows you to remove old wood while new canes are still growing and easy to distinguish. The principle is simple: cut out all canes that have just fruited, right down to ground level. These canes will not fruit again and quickly become woody and congested if left. Use sharp secateurs or loppers, and wear thick gloves—blackberry thorns are vicious. Remove the old canes entirely from the plant and dispose of them; don't leave them tangled in the wires. You'll notice vigorous new green canes that have grown during the summer. These will bear next year's fruit. Select the strongest four to six canes per plant and tie them into your wire support, spacing them evenly to allow air and light to reach all parts. Fan them out or train them along the wires in a systematic pattern—many gardeners use a fan or rope system to keep fruiting and new canes separate during the growing season. Cut out any weak, damaged, or excess new canes at ground level to prevent overcrowding. In late winter (February), tip-prune the retained canes by removing the top 10–15 cm to encourage side shoots, which will carry the fruit. If your variety is thornless, the job is far more pleasant, but the principle remains identical. Regular annual pruning keeps blackberries vigorous, healthy, and cropping reliably.
Common mistakes
✗ Finally pruning after five years of neglect
A drastic prune after years of nothing triggers an explosion of watershoots and almost no fruit the next year. Better to gradually restore over 2–3 years than do everything in one winter.
✗ Pruning blackcurrant the way you prune redcurrant
Blackcurrant fruits on one-year-old wood, redcurrant on short, multi-year spurs. Prune a blackcurrant for shape (like redcurrant) and you'll harvest nothing.
✗ Pruning during frost
Wounds don't heal in frost and the wood can split. Wait for a frost-free day, even in winter dormancy.
Hold off on pruning
Better to wait than prune at the wrong moment. The next optimal window is August. Until then: leave the plant alone — only remove dead or diseased wood (which you can do year-round).
