How to prune blackberries – and train them for easy harvesting next year

Blackberry bushes grow fast, so they require a little TLC every year to keep them in check. That’s why it’s so important to learn how to prune blackberries.

If you have blackberries in your garden, they can quickly get out of hand; they're vigorous growers and will keep you on your toes even as we head into autumn. Blackberries are a prime example of plants you should prune in September – and cutting them back now will promote a strong crop of berries next year. It will also make them easier to harvest next year.

Learning how to prune blackberries is straightforward, so don't worry about it being another big task to add to your September back-to-school to-do list. Here’s how (and when) to do it so you don't waste any time getting those bushes under control.

What you'll need

• A blackberry plant, like Blackberry 'Thornless Evergreen' from Thompson & Morgan (for no thorns!)
• Some secateurs, like the Kimura® 8" Pro Bypass Garden Secateurs, £21.95 at Amazon (they're one of my favourite pairs of secateurs!)
• A pair of loppers for thicker canes, like the Spear & Jackson Razorsharp Telescopic Ratchet Anvil Lopper, £27 at Argos
• Plant supports, like this shrub support trellis, £29.99 at Crocus
• Some garden twine, like this jute string twine from Amazon

1. Prune at the right time

First things first, you need to figure out when to prune blackberries. Generally, it's best to tidy them up in late summer or autumn, after the plants have stopped producing fruit.

‘The best time to prune blackberries is straight after fruiting,’ says Kris Collins, Thompson & Morgan’s nursery manager.

That way, you can be sure you're trimming away at older canes instead of new ones, which will grow and produce fruit the following year.

Pruning blackberries every year will make them more productive and stop them from growing out of control (and no one likes figuring out how to get rid of brambles!).

2. Cut back the canes

Learning how to prune blackberries is simple: you just need to identify which canes (branches) have fruited this year, and trim them right back.

'Cut back the old canes that fruited this year down to the base, as they will not produce again,’ says Chris Bonnett, owner of Gardening Express.

It's crucial that you leave the newer, one-year-old canes alone, though, as they'll become the two-year-old floricanes that produce blackberries next year. Younger canes will look greener, while the older canes will be brown and woodier, likely with remnants from this year's berries.

You'll need a pair of good gardening gloves when pruning blackberries, because the thorns can be sharp. Make sure you clean your garden tools properly after pruning, too.

3. Tie in the new canes

Once you've cut the older canes back, you can start training the newer canes to keep your plant healthy and prevent overcrowding.

'Tie in the new season’s fresh, green canes, which will carry next year’s crop,' says Kris from Thompson & Morgan.

'A simple tip is to train new canes in one direction along wires or supports, and keep fruiting canes in the other – it makes pruning and picking far more straightforward.'

Using a post and some wire, or a trellis, is the best way to train blackberries. You can buy wooden fence posts from B&Q, or try Garden Trading's Barrington Set of 3 Raspberry Stakes for £32. You could also browse other plant supports, depending on the size of your blackberry bush.

It's also a good idea to mulch around the base of your blackberry bush to protect the roots from winter frosts.

And that's that! Cut old blackberry canes back after they've finished fruiting, and then tie in new canes for next season. Simple!