How do I train and prune a blackberry?

A blackberry left to its own devices makes a mound of canes in which last year's dying wood and this year's new growth are hopelessly tangled, and picking becomes a fight with a thorny thicket. Every training system for blackberries and hybrids — loganberry, tayberry, boysenberry — exists for one reason: to keep the canes that are fruiting now physically apart from the canes that will fruit next year, so that in August you can cut one lot out without damaging the other.

What you'll need

• Two end posts and three or four horizontal wires
• Soft ties or string
• Secateurs and long gloves
• Loppers for old thick canes (optional)

Step by step

1. Put up a proper support before planting.Posts with horizontal wires at roughly 45cm intervals up to about 1.8m. Blackberry canes are long, heavy and thorny, and retrofitting a structure around an established plant is a horrible job.
2. Choose a training system and stick to it.The simplest for a garden: fruiting canes tied to one side of the plant along the wires, new canes trained up the centre and then along the other side. Alternatives are the fan and the rope system, but the principle is identical.
3. Tie in new canes as they grow through the summer.They grow fast and get in the way if left. Keep them separate from the fruiting canes as you go — this is the whole system working.
4. Pick from the fruiting side.One side is this year's crop, the other is next year's. Picking becomes straightforward instead of a search.
5. Cut out every fruited cane after picking.Right down at the base, in late summer or early autumn. They will not fruit again and they harbour disease. Cut them into sections to get them out of the tangle safely.
6. Move the new canes into position for next year.Untie them from the centre and tie them along the wires where the fruited canes were. That is the annual cycle complete.
7. Thin the new canes if there are too many.Keep the strongest four to six per plant depending on vigour and space, and remove the rest at the base. Crowded canes give small fruit and poor airflow.
8. Tip the canes in late winter.Shorten any that have outgrown the space, and cut back winter-damaged tips to healthy buds.
9. Deal with tip layering.Blackberry cane tips root where they touch the ground and start new plants. Keep the tips tied up, or use the rooted tips deliberately as free plants and cut off the rest.
10. Feed and mulch in early spring.A general fertiliser plus potash in March, then mulch along the row. Blackberries crop heavily and are hungry.

Tips

• Thornless varieties such as Loch Ness, Oregon Thornless and Loch Tay make the whole job far more pleasant and crop well. Thorny wild-type varieties usually taste better.
• Loganberries, tayberries and boysenberries are all trained and pruned exactly the same way.
• Blackberries crop well on a north or east wall, which makes them a useful fruit for the shadier boundary.
• Long sleeves and gauntlet gloves for a thorny variety. The canes fight back and the scratches get infected easily.
• A blackberry against a fence with wires can be productive in a metre and a half of border, which is a good return for the space.

Common mistakes

• Letting new and old canes grow together — In August you cannot cut out the fruited canes without damaging the new ones, and you end up either losing next year's crop or leaving disease-carrying dead wood in the plant.
• Leaving fruited canes in over winter — They are dead wood that carries disease and shades the new growth. Cut them out as soon as picking finishes.
• Planting without a support structure — A blackberry cannot support itself. Without wires it becomes a mound that is impossible to prune or pick.
• Letting cane tips root wherever they land — You get a colony rather than a plant. Keep the tips tied up, or take the rooted ones deliberately and remove the rest.

Questions people ask