With their fragrant dark purple-black, juice-filled fruits and glossy exterior, blackberries (Rubus fruticosus) thrive under full sun in sandy, acidic soil in U.S. Department of Agriculture hardiness zones 5 through 10. As their vines never cease to grow and their roots can reach up to 10 feet below soil surface, blackberries are hardy plant once established, even if their fruit is fragile and fleeting.
Blackberries can be early, mid- or late-season varieties, and the ripening times of the berries depends as much on your local weather as the type of variety. Early harvest blackberries such as “Brazos” grow best in USDA zones 8a through 10b. These types of berries, because they ripen so quickly and early on in the growing season, are ideally suited for regions with very hot summers. Other blackberry varieties that are better suited to regions with cooler summers include Himalayan blackberries (Rubus armeniacus), which do best in USDA zones 5b through 10b. These blackberries tend to ripen midseason as they are able to adapt to cooler climates.
Blackberries will follow the same ripening process, where small hard, green-colored berries will form where pollinated blossoms have been. When they are still unripe, blackberries will appear green and then turn red. These blackberries are still not fully ripened until they swell up and exhibit a plump, glossy exterior, are slightly soft to the touch, are easily removed from the canes, and have a dark, blue-black to purple-black exterior.
Blackberries are often called perennial plants, because their roots live past two years, which means that they will return each year. However, the canes, where the berries are produced, are considered biennial. The first season of growth for canes will not produce fruit on those primocanes, but will produce fruit the second year, when they are floricanes. After that point, the canes will die and will no longer bear fruit. Shorter canes branching off of the floricanes will produce the actual fruit, and blackberry bushes will have canes in various stages of growth and development at any given point in time. This will ensure an annual harvest after the first year of growth. After the second year, floricanes are often pruned to prevent mildew, fungi or bacterial disease from taking hold of the plant.
Blackberry bushes have naturally occurring suckers that can eventually become individual bushes. If you hoe or rake the soil surrounding the base of the blackberry bush, you can encourage these suckers to establish themselves around the foot of the original bush as a “new” blackberry bush. These suckers will grow where they naturally occur, or they can be transplanted to a more accessible or appropriate growing spot. Transplant the new plants early in the growing season so they can establish themselves throughout the year. The young blackberry bushes will begin caning the following year.