Pruning raspberries in September: which canes to cut and which to keep

Mr. Fässler from the neighbouring village cut all his raspberry canes last year. Every last one. Neatly back to twenty centimetres, early September, because he'd read that you prune raspberries in autumn.

He was right. And he was wrong. And he had no raspberries the following year.

The problem is that there are two different types, two different pruning times, and two completely different sets of rules. If you don't know which is which, you'll do the wrong thing with total confidence.

Summer raspberries and autumn raspberries: the difference that changes everything

Summer raspberries fruit on two-year-old canes. That means: a cane grows in year one, fruits in year two, and then it's done. Dead. It will never fruit again.

Autumn raspberries fruit on one-year-old canes. That means: a cane grows and fruits in the same year. By autumn it's finished, and next year a new one takes its place.

The pruning timing is therefore completely different:

• Summer raspberries: September to October — remove the old fruited canes, leave the new ones
• Autumn raspberries: February to March — cut all canes to the ground and let them regrow

If you don't know which type you have: check whether your raspberries are still carrying fruit or just finishing up. If yes, put the secateurs away until after the last harvest.

Pruning summer raspberries now: how to tell the canes apart

In September, the old canes of a summer raspberry are easy to spot:

Old canes (cut these out):

• Brown to grey-brown, woody, with cracked or peeling bark
• Carry withered leaves and the stubs of old fruit stalks
• Sometimes leaning or drooping slightly

New canes (leave these in place):

• Green to light brown, smooth, firm
• Standing upright and strong
• Often still carrying green leaves that won't fall until October

Cut each old cane as close to the ground as possible — right above the soil or above the nearest new side shoot. Use clean, sharp secateurs. Dirty blades spread fungal disease from cane to cane.

When in doubt: leave one old cane too many rather than accidentally cutting a new one.

How many new canes should stay?

This is the question most gardeners don't ask — but it matters enormously.

Too many canes means too much fruit that stays small and ripens unevenly. Too few means a smaller harvest.

A good rule of thumb: six to eight strong canes per running metre of raspberry row. That's enough for a solid harvest. Any extras that have come up can be thinned out once the old canes are gone.

Choose the thickest, straightest, most vigorous ones. Weak, thin, or crooked canes only ever produce small fruit.

What to do with the prunings

Don't compost the old canes if you're not sure how healthy the plants have been. Raspberry diseases overwinter in compost and come back to the bed the following year.

For healthy plants: fine to chip or compost. For suspect canes (spots, galls, misshapen fruit): bin them, don't compost.

What else to do now

Mulching helps. A thin layer of bark mulch or straw around the base of the canes keeps the roots warmer and suppresses the weeds that love to come back in autumn.

If you have a support system (wires between posts, a trellis), tie the new canes in loosely now. Canes left hanging freely are more likely to snap under the weight of snow and ice in winter.

Stop feeding. No potassium, no compost until March. Anything you apply now pushes soft new growth that won't survive the first hard frost.

What you absolutely shouldn't do

Don't cut all the canes. I know it's tempting when you read "autumn pruning". But summer raspberries need their new canes to fruit next year. No new canes = no harvest in 2027.

And once more for Mr. Fässler: if you're not sure which type you have — leave everything alone until March and ask someone who knows.

🦔 Stachi