Tuesday, July 2, 2013

Bush Type Clematis: A Garden Treasure

 Bob Henrickson, Nebraska Statewide Arboretum
 Clematis is often called “queen of the vines,” and for good reason. I can’t think of another perennial vine that offers as much versatility in both form and color. Clematis (KLEM-a-tis) is a member of the ranunculaceae or buttercup family. One recent classification recognized 297 species of clematis, not to mention the numerous garden hybrids. Many gardeners think of clematis as vines that twine around a mailbox, trellis or arbor, producing masses of large, open-faced flowers. It’s true that most clematis are woody deciduous climbing plants, however a few are herbaceous, dying back to the ground in winter and emerging from the base in spring.
The clematis plants I’m going to describe are the shrub or upright clematis that are great for individual specimens or allowed to weave as a groundcover through a shrub or perennial border. These shrubby plants have handsome, compound leaves and showy bell or urn-shaped flowers, followed by silky seed heads. I have found these bush clematis to be hardy, very easy to grow and long lived in the garden when provided full sun to part shade and rich, well-drained soil. The shrub clematis selections have become easier to find in the garden center and recent breakthroughs in breeding have greatly expanded the selection of these valuable yet overlooked garden plants. I will focus on varieties that are both available and suitable for the Great Plains garden. 
Fremont's Clematis, Clematis fremontii. A Plains native, this clematis grows like a herbaceous perennial, up to 20” high. Its thick, leathery leaves emerge in early spring, followed by attractive 1” urn-shaped flowers with thick blue to purple petals, blooming in May. Like most clematis species, it can take several years to grow into maturity. This long-lived gem is one of my favorite garden plants and combines well with other spring bloomers, such as pasque flower or prairie smoke. It was named in honor of John C. Fremont, the famous explorer of the American West and the first to catalog this plant in the 1840s.
Ground Clematis, Clematis recta ‘Purpurea'. Ground clematis can be trained to climb, but is usually left alone to crawl along the ground or tumble down a bank or low wall. It has attractive rosy-purple new leaves in spring that turn green as the season progresses. In late spring and early summer it produces masses of small, white, star-like flowers. The vanilla-scented flowers are followed by silvery seedheads.
‘Mongolian Snowflakes’ Clematis, Clematis hexapetala ‘Mongolian Snowflakes’. This shrubby clematis grows into a sprawling 3’ high mound of rich, dark green linear leaves with parallel veins. In late spring, it is topped with clusters of 1” white, fragrant flowers, soon followed by feathery, bright silver seed heads. Both the flowering stems and the seed heads are excellent as cut flowers, each with a long vase life. This drought tolerant clematis is easy to grow in any sunny, well-drained site. ‘Mongolian Snowflakes’ was selected for its copious clusters of larger 1 1/2” flowers.
‘Mongolian Gold’ Clematis, Clematis fruticosa ‘Mongolian Gold’. This is a dwarf shrub with woody stems up to 3’ high and dark green foliage. In late summer, the clumps are topped with 1” yellow, intensely fragrant, bell-shaped flowers. Its non-clinging stems can lean against a support or allowed to tumble over a low wall. It is very drought tolerant and cold hardy and grows best in full sun and well-drained soil.
Rock clematis, Clematis columbiana var. tenuiloba. This prized rock garden clematis has ascending or erect 6” non-vining stems with longer stems trailing or leaning on neighboring vegetation or rocks. The slender, light blue flowers are held above the foliage in a nodding fashion. Prefers part shade and thrives in clay, limestone rubble or garden loam. When well-established this clematis is very long-lived. This lovely Black Hills native is hard to find, but worth looking for.
Sugarbowl Clematis, Clematis scottii. This beautiful rock garden clematis is from the southern foothills of Colorado’s Front Range, yet its winter hardy to 30 below. This non-vining clematis is slow to get going, but is a long-lived perennial when grown in rich, well-drained soils and full sun to part shade. It has showy 1” deep blue, bell-shaped flowers followed by fuzzy seedheads. 
Tube Clematis, Clematis heracleifolia var. davidiana. This China native is a tough clematis, with handsome, dark green leaves forming a 4’high perennial shrub. In late summer it is topped with lightly scented clusters of small, pale blue flowers that open with recurved petals. This easy-to-grow clematis needs full sun or the blooms will be sparse and the plant will be floppy. The seedheads are also very attractive. The cultivar ‘China Purple’ has deep purple-blue flowers.
Bush Clematis, Clematis integrifolia. This is the most common herbaceous clematis, growing up to 2’ tall with nodding steel blue flowers over upright clumps with many stems. This summer bloomer needs full sun or the plant will be floppy. If you prune the plant back after flowering, it will bloom again in late summer or early fall. Look for splendid new cultivars of bush clematis hybrids, such as ‘Olgae’ with large blue, bell-like flowers; ‘Rosea’ with clear sugar pink bells; ‘Arabelle’ with deep blue-mauve 3” flowers; and ‘Hanajina’ with purple-pink bells.
Mrs. Robert Brydon Clematis, Clematis x jouiniana. I grow this hardy, easy-to grow clematis as a groundcover between large shrubs. It’s a vigorous, non-clinging vine with many small bluish-white flowers in late summer to fall. In cold climates it dies back to the ground in winter and you’ll have to cut the stems back in early spring. Growing to 10’ it can be tied, allowed to cascade over a wall or used as a groundcover over an old tree stump. 

(Photos of six-petaled, Mongolian Gold and Fremont's clematis)

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