The parents of 'Cassandra' are natives of China and are sometimes referred to as tube clematis. This cultivar produces short clusters of small hyacinth-shaped, fragrant, blue tubular flowers that are ½ to 1 inch across, beginning in early summer. Unlike the climbing clematis, tube clematis forms a small shrub reaching 2 to 3 feet in size. It is a member of clematis pruning group 3, which includes species and cultivars that flower on the current year’s new growth. These plants require yearly hard pruning down to new buds in late winter or early spring. Grow tube clematis in full sun, either in the border or as a specimen plant.