Pruning a raspberry bush depends on when and how many times it bears fruit in a season.
We distinguish between two major types of raspberry bushes, depending on when they bear fruit. This means that there are (1) summer-fruiting raspberry varieties (yielding a single crop of berries) and (2) autumn-fruiting raspberry varieties, also known as everbearing (they can be pruned to produce one or two crops a season).
Red-fruited raspberries can produce one or two crops a season, depending on the variety. Raspberry varieties with yellow fruits produce two crops a season. Black and purple raspberries only bear fruit once in a season.
Raspberry canes can be a maximum of two years old – that is, they live for two years (raspberry canes either grow from the extensive underground root system of the raspberry plant or develop from above-ground shoots that bend down to the ground).
Single-fruiting summer raspberry varieties bear fruit on canes that developed the previous summer and then overwintered nicely. Double-fruiting or everbearing raspberry varieties bear fruit both on canes that developed the previous summer, as well as on young, new canes that sprouted that year.
Pruning Summer-Bearing Raspberry Varieties (Yielding a Single Crop of Berries)
Pruning a raspberry bush essentially consists of pruning back the canes from which the fruit has already been harvested.
The canes of the summer-fruiting raspberry should be cut back immediately after harvesting the ripe fruits. The canes should be cut back to ground level.
Note: don’t cut back the new canes that sprouted during the summer! After the old fruit-bearing canes have been removed, help the new canes run up onto stakes or onto one or two horizontal wires stretched between stakes. These young canes will bear fruit the following year.
If raspberries are grown in a row, thin out the new canes so that the distance between the remaining canes is approx. 15 cm. This way, the fruit-bearing canes will not be overcrowded the next season.
Pruning Everbearing Raspberry Varieties (Producing Two Crops a Season)
Double-fruiting or everbearing raspberry bushes bear fruit on the upper third or top of the new canes in the autumn of their first season, and laterally on the lower two-thirds of the same canes in the spring of their second season.
Cut off the ends of the canes from which the fruit has already been harvested. Cut the canes back to the lowest point where they still had fruit (this is usually 100-120 cm from the ground).
Leave the lower part of the cane so that it can bear fruit the following spring or early summer. After the fruit has been harvested from this part of the cane in the second year, cut it back to the ground. At the same time, run the young, new canes, which will bear fruit already in autumn, onto stakes or trellis.
It is a general practice that the lower two-thirds of the canes of everbearing raspberry varieties that bear fruit the following spring or early summer are allowed to run up stakes or a trellis. If you don’t want to follow this practice, prune back all the canes after the autumn harvest; this means that you will only be able to harvest fruit once from your double-fruiting or everbearing raspberry bush.