The black currant (Ribes nigrum) is a deciduous shrub, up to two metres tall with finely hairy shoots. The leaves, glabrous on the upper side and hairy at the bottom, are two to five centimetres wide and roundish to slightly lobed. They appear in April and, when rubbed, give off a strong smell similar to that of the black elderberry
Blackcurrants are one of the few fruits that have been native to Germany for thousands of years. The wild relatives of the garden varieties grow on humid sites in riparian forests and alder swamps. The aromatic berries can remain on the bush for a relatively long time without spoiling and are a real treat in the garden as a sweet fruit.
The berry bushes, botanically belonging to the gooseberry family (Grossulariaceae), were probably already cultivated by the Germanic tribes. The black berries have a very high vitamin C content and are very rich in anthocyanins and other secondary plant substances that protect our body cells from damage by free radicals. Blackcurrants can be processed into juice, jelly, jam as well as desserts and cakes.
Location and soil
Currants grow in deep and preferably moist soils rich in humus and nutrients. Depending on their location at the edge of the forest and in clearings, the small bushes in the garden also thrive in partial shade, but in sunny locations they produce more aromatic fruits.
Planting and maintenance
Currants can be planted as container plants all year round. Bare-root shrubs only grow reliably after the leaves have fallen in autumn or before the first shoots in spring. If you buy the shrubs in a pot, you should make sure that the pot ball is firm and well rooted and that the shrub has five to seven strong, upright-growing shoots. Currants should be planted quite deep to encourage the formation of adventitious roots and new shoots. You should then water the shrubs well.
Blackcurrants are usually cultivated as shrubs, but they can also be grown as high-stemmed shrubs. For this purpose the Gold currant (Ribes aureum). It requires less space due to its narrow and tall growth, but is less productive than currant bushes.
Black currants are somewhat more sensitive to drought than red currants and require a good water supply until they ripen. Otherwise they often shed their flowers and the berries remain very small. In summer, a layer of mulch can help to keep the soil moist and suppress weed growth. You should fertilize at least every three years in early spring. Organic berry fertilizer or compost mixed with horn meal is suitable for this.
Raising and cutting
Black currants are more vigorous than red and white currants. They must be thinned out relatively generously, otherwise the main branches age too much and hardly develop any side shoots. When pruning, only the five strongest shoots should be left standing and shortened by about half. All other shoots are cut off at ground level.
In contrast to other currants, the flowers and fruits are formed on the long main and side shoots, which were produced in the previous year. The older the branches become, the weaker their side shoots become and the lower the yields. Every year after harvesting, the one to three oldest main shoots are cut off and the corresponding number of new shoots are left to replace them. Rule of thumb: The shrub should consist of seven to ten main shoots, which are not older than four years. The remaining ground shoots are also removed. The old main shoots can be easily recognised by the dark bark of the black currant. The tips of the remaining main branches are diverted to strong, preferably steeply standing side shoots. Only two strong side shoots remain per main branch in addition to the new tip. Everything that branches off below knee height is rigorously cut off. Since this pruning technique leaves only relatively few fruit shoots left for the next year, the shrub produces especially grapes with very large berries.
If your black currant has not been pruned for years, you can cut the entire shrub just above the ground in late winter and rebuild it. Blackcurrants are extremely capable of regeneration, and will bud out again vigorously. However, you must then forego your own harvest for at least one season.
The flowers of blackcurrants are pollinated by bees and other flying insects. Most varieties are self-fertile, but cross-pollination by a second bush of another variety in the immediate vicinity significantly increases the yield. Red and white varieties are not suitable as pollen donors for blackcurrants
Harvesting and utilization
Blackcurrants are ripe between June and July. The later you pick them, the sweeter they taste. For jelly and marmalade it is better to pick them a little earlier because the pectin content is higher then. The berries can be kept refrigerated for about one to two weeks. Blackcurrants can be eaten directly from the bush, but are also used as a fruity ingredient for cakes and desserts. They can also be made into liqueur, jelly, jam or juice.
Like all currants, blackcurrants can be easily propagated by using plugwood. After the leaves have fallen, cut off about 20 centimetre long, one- to two-year-old twigs and place them in a shady, sheltered place in a bed of loose and humus-rich, moist garden soil. Until spring the twigs will form roots and sprout. In summer, propagation by cuttings is also possible. Young, not yet completely woody shoots are used for this
The varieties of blackcurrants differ in fruit and grape size, health, ripening time, frost resistance and taste
Hedda’: sweet and large berries suitable for raw consumption, ripe from the beginning of July
- Silvergieters Schwarze’: Berries are aromatic, sweet and mild in taste and ripen from mid-June. They hang on long grapes and are ideal for compote and jam
- Daniels September’: tart fruit, medium-sized berries with high vitamin C content, suitable for processing into jelly and jam
- Wellington Schwarze’: old variety, fruits ripen already from the beginning of July; high yield of aromatic, slightly sour berries, which are particularly suitable for snacking, but also for compote, cakes and juice
- Ometa’: a rich variety with long grapes, good taste; robust variety, resistant to late frosts; harvest: mid to late July
- Titania’: very large berries; robust and productive; ripens from mid-July
Diseases and pests
Blackcurrants are relatively insensitive to disease, provided they are pruned regularly. American gooseberry mildew occurs occasionally. It can be seen in white fungal spores on the young leaves and fruit and on brown shoot tips. As a preventive measure, you should plant resistant varieties and ensure that the location is not too dry Affected areas should be cut out and disposed of in the residual waste. By the way: Jostaberries, a cross between black currant and gooseberry, are even more resistant and less susceptible to diseases.
Only one physiological reaction is the so-called “trickling”: The plants shed their flowers and only a few berries are formed on the grapes, resulting in a small harvest. Mostly spring frosts, a long dry period or a lack of pollination are the cause. If you plant several varieties close together and make sure that the soil remains evenly moist, you will prevent this reaction. The small blackcurrant aphid is a pest that appears on blistered leaves. If the infestation is low, it can help to remove and dispose of the leaves and shoots early.