While blackberries are hardy and in many ways self-sustaining, you can improve results by planting blackberry bushes according to regional zones. In zones 1 through 6, plant in early spring, after the risk of hard frost. In zones 7 through 11 you can plant in spring but also in late fall. In all climates, be careful not to let the roots dry out prior to planting.
Typically, the fruits are ready for harvest from July until October. In warmer climates you may be able to harvest ripened fruit as early as June. In all regions, harvest when the fruit is soft and turns dark purple or black.
Growth and anatomical descriptionBlackberries are perennial plants which typically bear biennial stems ("canes") from the perennial root system.[3]
In its first year, a new stem, the primocane, grows vigorously to its full length of 3–6 m (in some cases, up to 9 m), arching or trailing along the ground and bearing large palmately compound leaves with five or seven leaflets; it does not produce any flowers. In its second year, the cane becomes a floricane and the stem does not grow longer, but the lateral buds break to produce flowering laterals (which have smaller leaves with three or five leaflets).[3] First and second year shoots usually have numerous short curved very sharp prickles that are often erroneously called thorns. Prickle-free cultivars have been developed. Recently the University of Arkansas has developed primocane fruiting blackberries that grow and flower on first year growth much as the primocane-fruiting (also called fall bearing or everbearing) red raspberries do.
Unmanaged mature plants form a tangle of dense arching stems, the branches rooting from the node tip on many species when they reach the ground. Vigorous and growing rapidly in woods, scrub, hillsides and hedgerows, blackberry shrubs tolerate poor soils, readily colonizing wasteland, ditches and vacant lots.[2][4]
The flowers are produced in late spring and early summer on short racemes on the tips of the flowering laterals.[3] Each flower is about 2–3 cm in diameter with five white or pale pink petals.[3]
The drupelets only develop around ovules that are fertilized by the male gamete from a pollen grain. The most likely cause of undeveloped ovules is inadequate pollinator visits.[5] Even a small change in conditions, such as a rainy day or a day too hot for bees to work after early morning, can reduce the number of bee visits to the flower, thus reducing the quality of the fruit. Incomplete drupelet development can also be a symptom of exhausted reserves in the plant's roots, or infection with a virus such as Raspberry bushy dwarf virus.
In botanical terminology, the fruit is not a berry, but an aggregate fruit of numerous drupelets.
Blackberries are relatives of the rose and were found in Asia, the Americas and across Europe as far back as 8,000 B.C. Soldiers fighting during World War I drank blackberry juice to prevent ailments such as gout and diseases of the mouth and throat. Blackberries are very popular in Britain and Northern Europe and grow well in cool regions.
Varieties There are more than 400 species of hybrid and cultivated varieties of blackberries planted in North America. Technically the blackberry is not a true berry like a blueberry or strawberry but rather an aggregate fruit; the berry is composed of many small fruits or drupes, each one with a pit or stone.
Blackberries are divided according to their growing habit -- trailing, semi-trailing and erect -- and come in thorned and thornless varieties. Thorned varieties include Brazos, Womack and Kiowa. Thornless varieties include Black Butte, Black Satin, Chester Thornless, Cumberland Blackcap and Marionberry.
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