Excellent for training on trellises, fences, porches and posts. Particularly effective used with climbing roses or scrambling through shrub roses and deciduous shrubs. Requires support to climb. Prefer evenly moist, well drained, rich, slightly alkaline soil. Ample moisture in summer and early autumn is particularly important. The foliage and flowers prefer a sunny location, while the roots prefer a cool shaded situation. Annuals, perennials, ground covers, but not mulch, are satisfactory to shade the roots.
Pruning practice is related to flowering time and is divided into three groups with the corresponding Roman numeral appearing after the varietal name.
Group I: These clematis are the earliest to bloom, with the buds coming from the previous season's stems. Thin and lightly prune to shape immediately after bloom.
Group II: These include many of the most spectacular and longest blooming of all clematis. They bloom primarily from the previous year's stems, and therefore should not be pruned too heavily. Prune every year, in early spring just as the leaf buds start to unfurl. Remove dead or weak growth; prune only as far back as the first strong leaf buds. Spread and loosely tie the vines to their supports immediately after pruning. The Group II varieties are usually midseason bloomers, with later blooms coming on the current year's growth. After the initial bloom fades, a light pruning enhances this rebloom.
Group III: These late-blooming clematis produce their flowers on the current season's growth. They are best rejuvenated with heavy pruning every two to three years. Prune back to the lowest strong leaf buds (9 to 18 inches above ground level) in late winter or early spring. These varieties tend to make one very spectacular display. Delaying some pruning until March, or even April, will extend their blooming season. In years when rejuvenation is not required, a light trim in spring is beneficial. These are the best varieties to use intermingled with roses or other shrubs that require frequent pruning.
Two or even three contrasting varieties, with the same pruning requirements, planted together make an incredible display.
Alan Summers, president of Carroll Gardens, Inc., has over 30 years experience in gardening and landscape design. He has made Carroll Gardens one of America