Raspberries that bear fruit in summer should be pruned in late winter. In doing so, remove the worn-out shoots near the ground and all the weaker new shoots, leaving only the strong ones. Between around five and seven shoots should be left per metre. They should then be attached to a trellis in a bow formation. If the shoots are too long, they can be cut to suit, however this will reduce their yield a little.
Raspberries that bear fruit in autumn should be pruned completely in late winter.
For blackberries, proceed as follows:
Systematically remove all shoots that have borne fruit in the last year, as well as all weak or superfluous shoots. Around five strong shoots that have grown during the previous year should remain on the plant. Shorten their branches to between three and five buds. Fasten these shoots from last year onto one side of a trellis which has been divided into two halves. Arrange the shoots in a fan shape. There should be a gap of around 50 centimetres between the shoots. Shorten any branches that are too long, to between 1.5 and 2 metres. Connect this year's shoots to the empty side of the trellis in the same way. Each part of your trellis therefore has a fruit-bearing and a growing side. By cutting away worn-out branches, you are creating space for new ones to grow. Simply follow this pruning and tying pattern every year.