Clematis grows over an arbor.
“All your beauties were seldom hidden
‘Under the dark shadow shadow,
But still to win the loftiest spray,
Your weak tribe makes its efforts;
Well, every obstacle overcome,
You smile from your green home.”
– “The Clematis”, Alexander Bathgate, in “Far South Fancies”, 1890
Alexander Bathgate (1845-1930) was a Scottish lawyer, journalist, conservationist and poet who wrote often about his adopted homeland of New Zealand. His poem “The Clematis” pays homage to C. paniculata, or “puawhananga” in Maori, the most common of seven native clematis species in New Zealand.
I, too, want to pay tribute this week to Clematis, a widespread genus of woody and herbaceous perennials in the Ranunculus (buttercup) family, found in all temperate regions of the world. I have three non-native species growing in my garden in Medford, two of which have already charmed me with their showy blooms in early and mid spring.
C. armandii, or evergreen clematis, is a woody climber with leathery foliage that bears white, star-shaped flowers in March. My very floriferous C. montana var. rubens covers an arbor in my backyard in May with large, pale pink flowers and light green stamens. I also have a pretty Japanese variety with lavender flowers that blooms later in the summer.
In fact, there are more than 250 known species and thousands of cultivars of clematis, which take their name from the Greek “klema” meaning “climbing vine”. Depending on the species, clematis flowers have between four and eight “petals,” which are actually sepals (modified leaves) surrounding contrasting-colored stamens. Clematis became popular as a garden plant in Europe and America in the 18th century. Widespread in Victorian England, clematis was associated with spiritual beauty in the “language of flowers.”
Clematis is called the “queen of the vines” among plant lovers for a reason. However, not all Clematis species are climbing plants. I recently visited Italio Gardens and Nursery in Medford where owner Baldassare Mineo showed me his collection of herbaceous clematis in the non-twining Integrifolia group. These shrubby clematis produce nodding, urn-shaped purple flowers from late spring through fall, depending on the variety.
There are 12 different classifications of clematis: evergreen, alpine, macropetala (downy clematis), montana, rockery, early large-flowered, late large-flowered, herbaceous, viticella, texensis, orientalis, and late mixed species. The Gardener’s Path website provides a useful description of each of these classifications at gardenerspath.com.
There are about 30 species of clematis native to North America. These include C. ligusticifolia, C. columbiana, C. texensis, and C. crispa. Although the blooms are often less showy than non-native clematis, native clematis are disease resistant and tend to play well with other plants in the garden.
Each clematis species falls into one of three pruning groups. Group 1 consists of the early bloomers (winter to mid-spring), such as BC armandii and C. montana. They form flowers on shoots of old wood, so they should only be lightly cared for after flowering. A strong pruning is not necessary.
Group 2 includes early, large-flowered varieties that bloom for the first bloom on old wood, then on new growth for a second bloom in late summer or early fall. These clematis should be pruned in early spring when new buds are emerging by lightly cutting back up to a third of the stems to a pair of buds about 12 inches above the ground. To encourage a second bloom, prune again after the spring flowers have faded.
Group 3 are the late large flowered clematis like my Japanese variety and the herbaceous clematis. They produce flowers on new growth throughout the current season, so they should be cut back heavily in late winter or early spring (or just let the plants die off on their own and then remove the debris in spring).
According to Ashridge Nurseries of Somerset, England, there are five key considerations to successfully growing clematis: preparation, depth, water, temperature, and initial pruning.
Find a spot in your garden where the clematis gets at least six hours of sunlight. They like well-drained soil with a pH around 6.0 to 6.5. Climbing species require a trellis or other support. Dig a hole twice the width and depth of the root ball and place the plant so that the crown is about 3 to 4 inches below the surface of the soil. Put bone meal and compost in the planting hole, fill up, water thoroughly and mulch.
Be sure to keep clematis moist, especially as they become established in the garden. My adult clematis don’t need much water. Some gardeners say clematis are heavy feeders, but I just add fresh compost and mulch annually and they seem to work well.
I’ve learned that one of the most important aspects of growing clematis is keeping their roots cool and allowing the vines to grow towards the sun. One of my C. armandii is uncomfortable in its container because the soil heats up in the late afternoon sun. I need to put the pot in a spot on my patio where it doesn’t get as much direct sunlight but where the vines get the sunshine they need to bloom profusely.
After each type of clematis is planted, prune them back to 6-12 inches during the first growing season to encourage branching and a bushier plant. Then follow the pruning recommendations for your specific clematis group.
Some gardeners recommend planting a groundcover or other plant around the clematis to shade its roots, which has the added benefit of hiding what English gardener and author Christopher Lloyd famously called the clematis’ “bad legs.” However, other gardeners claim that so-called companion plants can stifle clematis root formation, and some mature clematis can grow aggressively and overwhelm other plants in the garden.
Despite this warning, clematis are often grown effectively around the base of trees where they are allowed to climb up the trunk, or planted under a shrub and can twine through the branches.
We are fortunate to have the Rogerson Clematis Garden in West Linn, about 270 miles north off Interstate 5 from Medford. The garden is a nationally recognized collection of clematis with more than 2,000 individual plants. Garden curator Linda Beutler wrote Gardening With Clematis (2004), the thought-provoking book about growing healthy, happy clematis in our gardens.
I’m not sure if Alexander Bathgate was an expert on clematis, but he was certainly smitten with the New Zealander. He wrote about C. paniculata:
“Beautiful crown of stars of the purest ray,
Suspended high on the mapau tree,
What floral beauties do you show
Stars of snowy purity…”
Rhonda Nowak is a gardener, teacher, and author from Rogue Valley. She founded the Bard’s Garden at Central Point. Learn more at literary garden.com; Email Rhonda at Rnowak39@gmail.com.