Its certainly recommended that you do this with summer fruiters. If nobody gives you better advice why not do half and see if it does affect the crop? I wouldn't expect it to.

I'll certainly try cutting half of them this year. Thanks

Istrachan autumn fruiting raspberries should be cut down to 6 inches above the ground in February/March, they will then grow the new canes which will fruit in autumn.

According to where you are in the UK, you can cut them down earlier than MG (who is in Scotland)

I'm in Berkshire, and I've already cut mine down. In colder areas, it should be delayed.

Good point Andrew... Yes in southern England they can be cut down now.

I was given some advice (not tried yet), to cut down autumn rasps by 1/3 and you can sneak in an extra crop in summer from them. Might be worth doing that on a cane or 2 to try to see if it works.

Thanks for the replies. I'm new to this site and wow! what great responses, advice and suggestions. I live in south-east Scotland and usually cut mine right down to the ground in late Autumn/early Winter. I would really like them not to grow so tall, as in recent years they've grown to 6ft or so and are pushing through the top of my net fruit cage and the birds get a good feed. I wondered what would happen if I cut the growing tips before the fruiting flowers appeared.

If you are cutting the new canes to the ground and they then grow too tall yes lop them!

Good luck with the advice toy were given Kildermore - personally I wouldn't try it as I see no reason to do so.

I have tried leaving a few canes uncut just to see what happened and they cropped early but not heavily.

Kildermorie you mat you may get fruits but if you already have summer fruiting raps. why try?