Grow your own fruit at home with the Southern Living 2 gal. DownHome Harvest 'Osage' Thornless Blackberry Bush. 'Osage' Thornless Blackberry is a new variety of blackberries added to the DownHome Harvest Edibles Collection! This blackberry bush is self-fertile and produces round and firm, medium-sized berries. This fruit traditionally begins to ripen in late spring or early summer. In addition, the 'Osage' blackberries are outstandingly flavorful. They're the most intensely flavored of the 3 blackberries in this collection, which also features the 'Prime-Ark Freedom' Thornless Blackberry and 'Navaho' Thornless Blackberry.