Blackberries (Rubus) are produced by various species of woody plants, all which are members of the rose familymembers. The shrubs create sweet, elongated purple-black fruitsand vegetables. Based on the species, blackberry bushes have either erect, semi-trailing or trailing growth habits, with canes which can be thorny or thornless. The western indigenous blackberry (Rubus ursinus), sometimes called “dewberry,” is hardy at U.S. Department of Agriculture plant hardiness zones 3 through 9, and is the progenitor of many large-fruited varieties.
Ripening in July and August, “Triple Crown” is a semi-erect variety, with canes that grow 12 to 15 feet long. It was introduced in 1996 and is hardy in USDA zones 5 through 7 or higher. Even though it’s sometimes called “boysenberry,” Rubus “Boysen” is actually a thornless trailing blackberry variety with large, nearly seedless fruit. Descended in the thorned plant of the same name, it’s hardy in USDA zones 6 through 9.
A trailing variety developed in the University of Oregon, “Black Butte,” was introduced in 1997. It’s hardy in USDA zones 7 through 9. Fruits are about two inches long and firm and ripen in early summer. The highly productive “Kotata,” another trailing blackberry also developed in Oregon is hardy in USDA zones 6 through 9. The plants bear fruit that’s especially firm and suitable for processing into jams or desserts. “Kotata” bears fruit at the center of the blackberry year
Blackberries, especially Rubus ursinus, have been hybridized with other members of the Rubus genus to produce offspring which frequently have large fruit with blackberry characteristics. One of these magnets is just a raspberry-blackberry cross, “Olallie,” a trailing plant, sometimes known as the olallieberry. It’s hardy in USDA zones 6 through 9. Bred from “Olallie,” “Marion” or marionberry, is hardy in USDA zones 6 through 9. Marionberry’s trailing canes are thorny and the small-seeded fruits ripen in mid summer. Another raspberry-blackberry hybrid “Logan” or loganberry, hardy in USDA zones 5 through 9, bears big reddish-purple fruit.
Many blackberry cultivars and species are extremely vigorous, some to the purpose of weediness. The bushes set fruit on old wood, so new plants will not produce until the next year. To get the biggest fruits, even from large-fruited varieties, the most important condition is ample, regular moisture during the growing season. Blackberries thrive in sunny sites with well drained soil.