Clematis: A perennial with spectacular blooms

The scientific names of plants can be tricky for many of us to pronounce. Often it’s because the names are long and twist our tongues in ways that feel unfamiliar, but sometimes even the relatively simple ones can trip us up. Let’s face it, not many people go around speaking Latin, so when we’re forced to try, we don’t always know on which syllable to put the emphasis. Take clematis, for example, which is a bit of a tomato/tomatoh situation. Many pronounce it CLEM-a-tis, while others say cle-MAH-tis. Who is correct, you might ask? Who cares, I say. My advice is always to just say the plant name as confidently and comfortably as you can, and everyone around you will assume you’ve said it correctly. However, you can also visit the NC State Plant Toolbox at https://plants.ces.ncsu.edu. Among other features, the Toolbox includes an audio pronunciation guide for each plant in the database.

Regardless of how you pronounce it, Clematis is a group of perennials in the Buttercup (Ranunculaceae) family that mostly serve as climbing vines or groundcovers, and frequently generate spectacular blooms. There are nearly 400 unique species within the genus of Clematis, each with slightly different characteristics, but many of the most common types found in gardens are the hybrid Clematis, Clematis x hybrida or Clematis x jackmanii.

Left: This Clematis x jackmanii hybrid features velvety dark purple flowers that contrast nicely with their greenish-cream anthers, the pollen-producing center part of the flower. Above right: Clematis armandii is an evergreen variety that grows to 15 feet or more, with smaller white fragrant flowers.

Above: Clematis viorna is a shade-loving species with a beautiful pink bell-shaped flower that hangs from the tips of stems in summer.

Both The jackmanii hybrids derive from a cross of two old English clematis varieties, generated by horticulturist George Jackman in the 1850s. Plants resulting from this cross are deciduous, twining vines that bloom on both old and new wood. Light pruning in late winter or early spring will reinvigorate the vines and keep them healthy and flourishing. They can spread up to 10-15 feet, though this is somewhat dependent on the structure they are climbing on. Flowers are large, 4-6 petal star-shaped blossoms in deeper shades of pink, purple and red.  

Additional clematis hybrids, derived from crosses of various origins, populate the nursery trade. Most share the characteristic of blooming on old and new wood and have large showy blossoms, though the color palette expands to include white, light pink, lavender, and other colors. Most hybrids prefer full or part sun, but like to have cool roots, and thus should be mulched or surrounded by other plants at their base.

There are a few non-hybrid clematis of note, for good or for bad. Clematis armandii is an evergreen variety that grows to 15 feet or more, with smaller white fragrant flowers in the late winter and early spring. This type blooms on old wood only, and thus should be pruned soon after flowering finishes. Clematis viorna is a shade-loving species with a beautiful pink bell-shaped flower that hangs from the tips of stems in summer. Since it blooms on new growth and dies back in the winter, it should be pruned heavily in spring. Finally, Clematis terniflora, known as sweet autumn clematis, is a pretty but weedy vine that is adorned by hundreds of white flowers in the fall.  Most states in the southeast and mid-Atlantic list C. terniflora as invasive, though it has long been a common pass-along plant due to its prolific nature. It should not be planted, as there are numerous more well-behaved alternatives to choose from.

Matthew Stevens is the County Extension Director and Horticulture Agent for North Carolina Cooperative Extension’s Pitt County Center. If you have questions about this article or gardening in general, please contact the Pitt County Extension Master Gardeners at [email protected] or 252-902-1705.