Usually called "brambles," blackberry bushes range in habit from upright to weeping or trailing and have prickly stems. Tolerate the occasional finger wound and harvest the tasty summertime fruits to eat fresh or in pies, preserves, syrups or even as wine. Some species or hybrids of blackberries possess such distinct qualities that they are better known as boysenberries, loganberries, marionberries, olallieberries or dewberries.
Overall, blackberry plants grow naturally in Asia, Europe, and South and North America in any variety of habitats: woodlands, coastal dunes, shrub thickets or mountain slopes. The University of Georgia acknowledges that blackberries comprise some of the most complex taxonomic origins and makeup of modern fruit crops. While literature often simply lists blackberries as species Rubus fruticosus, one of six species native of Europe, regional wild species and man-made genetic crosses among them allows different types to grow better in different climates and soils in temperate regions around the world.
Blackberries grow thorny stems called canes that renew each year from the ground. Canes live for two years, growing the first year ("primocanes") and then flowering and fruiting the second year ("floricanes") before dying. The canes bear coarse, stiff spines and deep green leaves comprised of three to five leaflets, the end middle leaflet always the largest. The leaflet edges are serrated. In early summer, many five-petalled white-to-pink blossoms adorn the canes and are pollinated by honeybees and the wind. Each blossom contains hundreds of ovaries that then develop into small fleshy fruits called drupelets that collectively form an aggregate fruit. This numerous cluster of fruits is commonly called a singular blackberry.
Generally speaking, blackberries are grouped or described based on the habit of their canes: erect/upright, trailing, or intermediates as semi-erect. In the United States alone, breeders in different climates and regions develop hybrid varieties based on bias and preferences. Eastern and Midwestern varieties tend to be upright with stiff canes while those favored in the West tend to be more trailing. Trailing blackberry plants' fruits develop slightly smaller, more openly spaced and earlier in summer than erect-type varieties.
Blackberries thrive in cool, humid regions with deep, well-draining soils that are not alkaline in general with lots of organic matter. They need winter chill during their dormancy to guarantee flowering in spring but do not survive bitterly cold temperatures, either. While modern hybrid varieties may demonstrate better cold hardiness, blackberries typically excel in USDA hardiness zones 5 through 9. Grow the plants with at least six hours of direct sunlight daily and make sure soil does not remain soggy or become overly wet during the winter. Regular moisture in the growing season promotes the best production of fruit and health of young canes that will survive and flower next year. In midsummer, the new canes may be pruned back no more than 25 percent to encourage branching. Prune out and discard old canes that already fruited; this task is easiest in late winter when the old canes die and shrivel, visually distinguishing them from the healthy young canes.
Many pests and diseases afflict blackberries, so start a fruit patch only with healthy, disease-free plants grown from a reputable supplier. Choose disease-resistant varieties, too. Interestingly, blackberries' high susceptibility to verticillium wilt leads gardeners to avoid planting them in parts of the property where potatoes, eggplants, tomatoes and peppers grew for the past two growing seasons. Consider placing a loose netting over the brambles in summer to dissuade birds and other animals from eating the fruits.