CLEMATIS: Always called the “Queen of Vines,” nothing else makes the spectacular show of a clematis in full bloom. In almost all zones, these magnificent plants decorate mailboxes, trellises and porches with cascades of some of the most beautiful blooms in the flower kingdom, and they’re not difficult to grow. There’s no reason you can’t add them to your landscape.Clematis Jackmanii Superba. And superb it is — the International Clematis Society lists it among its top 10. An improvement on the beloved C. x jackmanii, this variety is very free-flowering, producing masses of deep violet-blue flowers up to 5 inches across from mid- to late summer. A vigorous grower, ‘Superba’ can cover a trellis or shrub in a single season. Prune it back hard each year, because flowers are produced on new growth.