Pruning Currants and Berry Bushes
Blackcurrant is an easy-to-grow and valuable bush fruit: valuable because it is one of the richest sources of vitamin C, while ease of culture extends to. It also extends to propagating so that there is no excuse for keeping old and unfruitful bushes in the garden. Ten years is a good life for a blackcurrant bush.
Avoid at all costs the formation of a leg or stem on. Foundations for a good shape are laid when the young bush is first planted by cutting the existing shoots back to 2.5 cm (1 in) above the . Buds will break below these cuts and send up a cluster of shoots. In the autumn of the same year cut back half these young shoots, each close to soil-level.
Those remaining will bear fruit the following summer. They will give rise to side shoots destined to fruit the year after, along with the regrowth from the cut-back shoots. In autumn again it is time to prune out a proportion of the shoots that have carried fruit. A reliable rule of thumb is to remove – by cutting out close to the soil – a quarter of the old wood each year.
It is tempting to make pruning cuts just above vigorous young growths that arise about halfway up the older wood. But if many cuts are made at this height the bush soon becomes tall, spindly and weakened as the supply of vigorous basal shoots on their own roots dwindles. So be firm and cut low: there will be ample renewal each year to replace the missing top growth. As well as old wood removal, encourage further suckering by cutting hard back about a quarter of the new basal growths each autumn. Pruning to this pattern will give the ideal balance of older and younger shoots.
Suckering and rooting near the soil surface is the aim, and is encouraged by laying mulches of straw, peat or rotted compost over the root area in early summer to keep the soil cool and moist. By the same token it is unwise to cultivate around the bushes and risk severing roots. Just remove weeds by hand if possible or hoe very superficially.
RED AND WHITE CURRANTS
These are grown on a single stem or leg, and in this respect resemble the gooseberry, which also has similar pruning requirements. When cuttings of these currants are rooted, the buds on the bottom 15 cm (6 in) of stem are rubbed or cut away to leave a clean leg. This will have been carried out on bushes purchased by the gardener. It is sufficient to keep four well-spaced shoots initially at the top of the stem, and to cut these back to three buds in the first winter. The following year a framework of about eight branches will be established.
Unlike the blackcurrant which fruits only on wood made the previous year, the red and white currants keep making fruit buds on the old wood year after year, so that old wood cannot be cut away without sacrificing a substantial amount of potential fruit. Suckers can arise from ground-level but are best torn away at the point of emergence in order to maintain a vase-shaped bush.
Many side shoots are made and these currant bushes will rapidly become a forest of growths unless pruned in summer as well as winter. This is done in late spring, shortening side shoots to within 8-10 cm (3-4 in), of the main branches.
Winter pruning consists of cutting the side shoots further, to two buds. This is also the time to reduce the new growth at the top of the main branches. For the first couple of years reduce the new extenion growth by a half, but as the bush matures be progressively more severe in limiting its height increase.
Birds like to eat unprotected buds on these currant bushes in winter, as well as sampling the fruit in summer, so it is wise to grow them within a bird-proof fruit cage.
To summarize the pruning process: preserve a clean stem or leg; establish a vase-shaped structure of about eight main branches; shorten back all side shoots in summer and again in winter, and tip prune leaders in winter. Allow for the occasional replacement of an original branch by a suitably placed younger one.
Red and white currants can be trained as cordon bushes to economize on space in the garden. Wires strained between posts are the ideal support. Set the bushes 30 cm (1 ft) apart sloping at an angle of 45° and tied to a bamboo cane which is itself attached to the wires. Allow only one branch to grow as the leader, which should be tip-pruned back by one-third of its annual extension growth each winter. Prune all side shoots to 10 cm (4 in) in summer, then cut back to about 1 cm (3/8 in) in the winter. Fruit will form in a column on these spurs. Cordon currants are less attractive to birds because they do not provide a good ‘footing’.
Gloves are essential when tackling gooseberries with secateurs, and are also advisable at picking time. Garden bushes are grown on a clean stem or leg and, as with red currants, a semi-permanent framework of branches is established. However, the gooseberry fruits on both one-and two-year-old wood, so that removal of a proportion of old wood each year will not jeopardize fruiting.
If the bush is pruned on a replacement system rather like the blackcurrant, it is likely to fruit heavily but these fruits will tend to be small and most suitable for bottling. If, on the other hand, a spur-pruning system is adopted, such as was described for the red currant, there may be fewer fruits but they will be large and of dessert quality.
So, if size of berry is not important, winter-prune the bush by cutting out at a low level the older central wood in order to open up the bush and make picking easier. New growth on the chosen leading branches should be cut back by a half. Pruning for quality involves summer pruning of all side shoots to 10-13 cm (4—5 in), followed in winter by ‘spurring back’ to 5 cm (2 in). From then on, regrowth from these spurs is cut hard back to base. Limit the number of leader branches to a maximum of eight, and in winter cut back the annual extension growth by about a half. Gooseberry varieties that have a drooping habit should be leader-pruned to counteract this tendency. Always make the cuts on the leaders to an inward- and upward-pointing bud. As with red currants, birds will go for the buds in winter and it is best to keep gooseberries in a fruit cage.
The great advantage of cordon training for the gooseberry (apart from being space-saving) is that picking is made so much easier. Training and pruning follow the pattern already presented for red and white currants. It makes good sense to grow both types of fruit on the same framework.
Autumn is the best time to plant new raspberry canes. Once planted they are pruned back to 30 cm (1 ft) from the ground, cutting just above a bud. The following year these canes will be developing their root systems and sending up new canes. It is these that bear the first crop of berries the following summer.
It is best to provide raspberries from the outset with supporting wires stretched between posts. The first flush of new canes the summer after planting should not be pruned, although weak ones are best removed. The original canes are cut out at ground-level that autumn.
Regular pruning and thinning out begin in the second summer. More new canes than are required are produced along the row, and weak ones should be cut out or hoed away when they can be distinguished. Make a point of removing those furthest from the parent canes in order to keep the row narrow and easily supported. As a rule of thumb, keep six at the most from the group that has sprung from the parent root.
Treatment of canes that have carried fruit is simple. Cut them all out at ground-level soon after picking, and burn them as a precaution against spread of disease. Then, having selected and retained the best of the new canes, these are tied securely but not tightly to the wires. A continuous looping run of soft string is a good way to secure them.
Early spring is the time to tip-prune the new canes, removing the top 8 cm (3 in). This is done partly to remove damaged tips and partly to stimulate fruiting shoots below.
With the autumn-fruiting varieties late fruit is borne on the current season’s growth and new canes must be cut down to about 10 cm (4 in) above ground in early spring.
A loganberry is generally trained in a fan-shape against a wall, fence or post-and-wire framework. After autumn planting the existing cane is cut back to 23 cm (9 in) above ground. Two or more new growths should arise at ground-level the following year. These are spaced and tied to horizontal wires with soft string. The next year these canes will bear fruit. Pruning consists of their complete removal after picking.
The loganberry grows vigorously and a disciplined approach to training is required to prevent it becoming unkempt. By the time the first fruit-bearing canes are cut away there will be a flush of new growths. The weakest can be removed at once and a maximum of eight strong ones tied down fan-wise on either side. Secure them so that the centre is left open to receive the following season’s new growths. These in their turn will be lowered to re-form the fan when the older ones are cut out. This effectively separates old and young canes each year, and also ensures that the young growths are ‘above’ the old ones and so are less liable to be infected by any disease spored on the older parts.
In the early spring tips of the canes which wave above the top wire — which should be 1.5-1.8 m (5-6 ft) high – are cut off. Growths that sprout an inconvenient distance from the parent root should be cut away at an early stage. These and blackberries are thorny subjects and gloves need to be worn during training and pruning operations. If planting for the first time take, advantage of the thornless varieties of both fruit that are available and which are much easier to manage.
The pruning and training approach described for the loganberry can be applied to the blackberry – though this fruit is even more precocious in its annual growth and needs a firm hand to keep it within bounds. It bears fruit on the same wood for several years but it is best to cut out growths after they have fruited.
In the second year lead the fruiting canes up and along the higher wire of the supporting framework, while the new growths are grouped together and tied in at the bottom. In their turn a selection of these will be trained upwards when the older ones are removed at the base after fruiting.
OTHER HYBRID BERRIES
Today, nurserymen offer certain hybrid berry fruits, most of which are akin to the loganberry or blackberry, while others have currants in their ‘blood’.
These fruits include the Tayberry, raised by the Scottish Crop Research Institute, and which produces very large bright purple fruits, with good flavour, in mid-summer. The individual berries are usually twice the weight of an average large raspberry, and are recommended for eating fresh, as well as freezing.
Then there is the thornless boysenberry. The black-red fruits are similar to a long-stalked loganberry, but are somewhat rounder. On the other hand the youngberry, which looks more like a blackberry, bears its dark purple berries in late summer, after the main raspberry crop.
What about the Worcesterberry? This is a gooseberry hybrid with medium sized, very dark red fruits, which demand the same cultivation as ordinary gooseberries.
Finally, the Japanese wineberry is attractive in growth, but has fruits of relatively poor eating quality.
All except for the Worcesterberry, prune as if you were tackling a loganberry.