Origin and appearance
The blackberry (Rubus fruticosus) is found in numerous wild forms that are found almost all over the globe. Botanists have described over 2000 species in Europe alone, which often only grow in certain regions. Nevertheless, the berry bushes are one of the great puzzles in the field of plant sociology, because it is controversial among experts whether they are really independent species or merely subspecies. In Central Europe, the blackberry, which belongs to the Rosaceae family, is one of the oldest fruit species. The berries were originally collected in the woods and the first large-fruited cultivars were probably already selected with the advent of garden culture in Central Europe.
All bomberries show a more or less strong growth and, depending on the variety group, form upright growing or rather low rank shoots. There is now an increasing variety of spikeless breeds. They are mainly derived from the USA variety ‘Thornless Evergreen’. Stingless blackberries usually show stronger growth and are more fruity, but until a few years ago the berries were considered less aromatic. This disadvantage was eliminated with the current variety generation like ‘Asterina’, ‘Oregon Thornless’ or ‘Navaho’. The leaves of the blackberries are alternate, winter green in mild winters and three to five parts with more or less strongly sawn edges. Some varieties like ‘Oregon Thornless’ have fern-like slit leaves. The flowers and fruits arranged in racemes form at the shoot ends and side shoots of last year’s rods. From a botanical point of view, the “berries” are so-called aggregated stone fruits. Each fruit cell has its own little stone.
Location and soil
In the wild, blackberries grow mainly in forest clearings, wild hedges and ruderal areas. However, they start most flowers at full sunny locations and here also the fertilization rates are highest because of the more intensive insect flight. In addition, the fruits need as much sun as possible to ripen well. Blackberries are less demanding on the soil than the related raspberries. It should not be too light, rich in humus and well permeable. Low-lime sites with pH values between 5.5 and 6.5 are more favourable. On heavy, very moist soils, dam culture is recommended, as is the case with raspberries.
Planting and care
Since blackberries are only offered as container plants in specialist garden shops, they can basically be planted all year round. In cold regions, planting in spring from May is ideal, as prickly varieties in particular are often somewhat sensitive to frost. In a milder climate, autumn planting is also recommended. Blackberries are placed on trellises or tension wires and planted about three finger’s width lower than they are in the pot to encourage the formation of new rods. After planting, the existing rods should be cut back to about 30 centimetres in length, and a sufficient planting distance is very important: plant upright varieties such as ‘Navaho’ with one metre, semi-upright varieties such as ‘Chester Thornless’ with two metres, and varieties with horizontal rods such as ‘Oregon Thornless’ with up to four metres between plants. After planting, the soil is thoroughly watered and covered with a thin layer of mulch, for example from dried lawn cuttings. The prickly varieties in particular sometimes have a strong tendency to runner formation. To prevent the blackberries from gradually conquering the entire garden, they should be planted with a generously dimensioned rhizome barrier. A 30 centimeter deep barrier layer of thicker pond liner is sufficient, since blackberries have relatively shallow roots. Blackberries do not require larger amounts of nutrients. Two litres of mature compost per square metre in March are sufficient for nutrient supply. On poorer soils the compost can be mixed with some organic berry fertilizer. Fertilizer should no longer be used from the end of July. A good and even water supply is important for the formation of beautiful large berries. If there is no rain, water in good time and do not wait until the soil has dried out. The mulch layer may need to be renewed during the season.
Education and editing
In order to prevent blackberry cultivation from ending in an inextricable rod thicket, consistent upbringing is necessary right from the start: Depending on the growth habit, guide the three to six strongest new rods up vertically to fan-shaped on a three to five-row wire palier (for upright growing species) or horizontally along the tension wires (for lower growing species). For fastening, for example, you can use stretchable hollow PVC cord. All excess rods are removed at ground level. Until late summer, the young rods form side shoots in the leaf axils. In September, these are shortened to about one hand’s width and in late winter cut back to two eyes. The fruit shoots develop from these in the course of the second season.
The spatial separation of the fruit and young rods is also important. So you always keep the overview and all rods are optimally exposed. With flat-growing varieties, for example, the old and new rods can be guided horizontally in opposite directions on the wire palier. With upright growing types, a fan-like education is meaningful, with which the old and young rods form one side of the fan in each case. The harvested rods are cut at ground level either after harvesting or in late winter and detached from the trellis. Cutting back immediately after harvesting has the advantage that the young rods can develop better, but should only be done in areas with mild winters.
Blackberries are self-fertile, but produce higher yields if several shrubs are planted. For a four-person household, however, two plants of a high-yielding variety such as ‘Navaho’ already provide enough berries.
Harvesting and recycling
Blackberries are the ideal naschobst, because the berries ripen gradually from the end of July and can then be harvested depending on the variety over a period of six to eight weeks daily and eaten directly or stirred into the yoghurt. You can tell the right stage of ripeness not only from the dark colour: the fruits have only developed their full aroma when they are soft and detach easily from the branch. In contrast to the raspberries, the ripe fruits of some varieties do not detach from the cone – they are simply eaten with it. In addition to fresh consumption, blackberries are also suitable for making juice, jelly or jam. The hard stones – the seeds – are not everyone’s cup of tea and can be sifted out after cooking. If you want to freeze blackberries, you should lay them out on a flat surface and pack them together in a foil bag only after freezing. So the berries do not freeze so strongly together.
The propagation of blackberries is very simple: In late winter you prick a few rods from the mother plant, prune them to a length of 20 to 30 centimetres and convert them into a new bed. Here they grow reliably into new blackberry bushes.
Diseases and pests
The most common fungal diseases of blackberries are grey mould (Botrytis), downy mildew and blackberry rust. They usually occur only in wet years. The risk of infection can be reduced to a minimum by a loose structure of the shrubs and ideally a rain-protected location in front of a house wall. Diseases of the rod occur less frequently in blackberries than in raspberries. If sick rods are cut off in time, the infection can be kept well under control and if the fruits are pale red on one side, they suffer from sunburn. If individual cells of the berries remain red and do not ripen, the blackberry gall mite will be atrocious. Heavily infested shrubs can easily be cut off completely at ground level in late winter. So the harvest is cancelled for one year, but next year you will have healthy, well ripened fruits again.
Blackberries in the our store-Shop
I am Don Burke, one of the authors at My Garden Guide. I am a horticulturist that cultivates, grows, and cares for plants, ranging from shrubs and fruits to flowers. I do it in my own garden and in my nursery. I show you how to take care of your garden and how to perform garden landscaping in an easy way, step by step.I am originally from Sydney and I wrote in local magazines. Later on, I have decided, more than two decades ago, to create my own blog. My area of specialization is related to orchid care, succulent care, and the study of the substrate and the soil. Therefore, you will see many articles dedicated to these disciplines. I also provide advice about how to improve the landscape design of your garden.