If you don’t prune raspberries regularly, within a few years you’ll end up with a dense tangle of branches that yields very little. Here are instructions for pruning summer raspberries and autumn raspberries.
The difference between summer raspberries and so-called autumn raspberries is essentially that the latter already bear fruit on the new shoots. The classic summer varieties, on the other hand, only blossom and fruit on the shoots that have already emerged in the previous year, but they also bear fruit much earlier in the season and are usually somewhat larger-fruited.
Pruning raspberries in spring and growing on wire trellis
Especially in the summer raspberries is important consistent growing on the wire trellis. As a rule, this is done by driving a wooden stake about every two meters (80 in) and stretching a wire at a height of about 30, 100 and 170 cm (12, 40 and 68 in) respectively. The new raspberries are then planted directly against the trellis with a planting distance of about 50 cm (20 in) and cut off at a height of 30 cm (12 in). Around mid to late May, when the new shoots sprouting from the ground are about 30 centimeters (12 in) high, select ten to twelve medium-strong, well-distributed shoots per running meter (40 in) for summer raspberries and cut off all others directly at ground level. During the season, the remaining shoots are fastened vertically to all three tension wires with non-incising binding material. In orcharding, a special tying pliers is usually used for this purpose, which fixes the shoot to the respective wire with a wide plastic band stapled together. If they grow beyond the top wire, they are cut off about a hand’s width above it in November.
For autumn raspberries, leave about twice the number of medium-strength young shoots per running meter in the spring. Since, unlike summer raspberries, the shoots are only cultivated as annuals, i.e. they are all the same age, time-consuming tying up is also not absolutely necessary. In orchards, the shoots are usually supported only by two lateral trellises. Sometimes they are simply allowed to grow through about one meter (40 in) wide sheets of construction steel mesh, which hang horizontally above the bed at a height of about one meter.
How to cut summer raspberries?
With summer raspberries it is important not to lose track. After all, from the second year of growth, two generations of shoots are always grown on the same trellis. The fruiting shoots from the previous year and the new shoots for next year’s harvest. For this reason, it has proven useful to cut off the old shoots directly at ground level in midsummer immediately after the last harvest. On the one hand, there is no risk of accidentally removing the young shoots, and on the other hand, the new shoots have a little more room to develop on the trellis.
When and how to cut autumn raspberries?
Raspberry varieties such as ‘Autumn Bliss’, ‘Himbo Top’, ‘Polka’ or the yellow-fruited variety ‘Golden Bliss’ also bear fruit on new shoots as so-called autumn raspberries. After harvesting in autumn, remove all shoots, i.e. cut off the entire raspberry bed close to the ground. A cover of autumn leaves protects the roots from frost. A thin layer of hoop compost provides nutrients and keeps the wind from blowing the leaves away.
With complete pruning, the risk of transmission of the dreaded shoot disease is largely eliminated. Next spring, new, healthy shoots will sprout again from the rootstock. With autumn raspberries you also beat the raspberry beetle, because at the time of their flowering the raspberry beetle no longer lays eggs and maggot-free fruits ripen from August to October.
How to cut two-timer raspberries?
The so-called two-timer raspberries, which are increasingly offered in garden specialty stores, are basically nothing more than autumn raspberries. All autumn varieties bear fruit twice if they are cultivated like summer raspberries, i.e. if they are not cut off immediately in the first year after the autumn harvest. The shoots then fruit a second time the following year in early summer. This method of cultivation is uninteresting for fruit growing, as harvesting takes longer and yields per harvest season are correspondingly lower. However, in the snack garden, where labor efficiency and maximum yields are not so important, the extension of the harvest season can be quite interesting. So you just cut them in the same way as summer raspberries, to enjoy two harvests.
Leave healthy shoot sections lying around
Cut raspberry shoots without signs of disease are usually chipped and composted or disposed of with green waste. Leave some of the shoots until spring. They serve as winter quarters for beneficial insects such as predatory mites. They move from here to the new shoots and attack the first generation of aphids, spider mites and other pests.