Pruning Red and White Currant Bushes
Red and white currants are closer to apples than blackcurrants in their fruiting habits, in that fruit is formed on the spurs along permanent branches. Whereas blackcurrants fruit on new wood, and are pruned to encourage the formation of new replacement wood, red and white currants fruit only on wood that is two years old or older. When pruning red or white currant bushes, the general idea is to form an open-centred bush with a permanent framework of eight to twelve well spaced branches.
Begin immediately after planting in the dormant season by cutting back all the main branches to half their length, making each cut just beyond a bud pointing away from the centre of the bush. Make sure there are three or four good buds remaining on the branch. Any weak or badly placed shoots should be completely rubbed out. This initial treatment may seem a bit severe, but if the newly planted bush is not pruned in this way, formative growth will be very slow. If your bushes are not being grown in fruit cages, and you have a problem with bird damage, it is best to delay this first pruning until just before bud-burst in early spring. You will then be able to see how much bird damage has been done, and can cut back completely any branches which have been entirely stripped of buds.
If you have bought a one-year-old bush, it will have three or four branches; a two-year-old bush should have six or eight strong branches. The pruning back of these branches to half their new growth is repeated for the next one or two years, in winter, until eight to twelve branches are formed; these will be the permanent framework of the bush. After this, it is only necessary to tip the branch leaders in winter, unless harder pruning is necessary to stimulate growth. If the crops gradually diminish over several years, it is a good idea to gradually replace some of the oldest branches with new wood. Select strong replacement shoots growing from the lower half of the bush, and allow them to grow out, and cut out the old branches, either back to their point or origin, or to a suitably strong one-year-old shoot low down.
Summer pruning consists of cutting back the sideshoots along the main branches to five leaves beyond which the new growth started in early summer. Do not cut back all the sideshoots at once or the balance between leaf and root growth will be disturbed; try to spread the pruning over a period of two weeks or so, starting just as the berries are beginning to colour. Summer pruning should only be done if the bushes are healthy and growing vigorously; if they are at all weak or slow growing, omit the summer pruning. Every winter, all these summer-pruned sideshoots should be cut back to the second leaf joint which by then will be a dormant bud, about 2.5 cm (1”) from the main branch. It is not essential to summer-prune bushes, but it does improve cropping and results in slightly earlier ripening.
In the case of cordons, cut back the new upward extension growth by a third of its length each winter, starting immediately after planting. Where growth has been very vigorous and more than 70 cm (27”) of new wood has been made, cut this new growth back to about 23 cm (9”). In summer, just as the fruit shows the first sign of changing colour, shorten sideshoots to five leaves and then in winter cut these back further, each to its second bud. Trained forms such as cordons and espaliers must be summer-pruned, if their shape is to be retained and cropping maintained.
Espaliers are formed in the same way as those of top fruit, choosing three shoots on the one-year-old such that the centre one is as near the vertical as possible and the other two opposite one another, so that they can be drawn to form the first tier.
For fans, all but two opposite shoots near the top of the leg are left, and the subsequent new growth pruned to produce shoots which fill the wall or fence in a fan-shape. Standards are simply a bush form at the top of a long leg, obtained by letting the leading shoot grow unpruned to the height required, and removing all side-shoots, then treating the head like a bush.