Seeds Clematis viticella Purple. Purple clematis is a late blooming, small-flowered climber from central southern Europe. The flowers are commonly violet-purple or rose red. These appear from midsummer to early autumn. Prune purple clematis in late winter as new buds begin to show low on the plant. Remove all dead material above the new shoots. Use on trellises, walls and upon and among large shrubs to add a vertical interest in the garden Growing 6-10 feet in zones 4-11.