Groundcover Clematis

Clematis texensis ‘Princess Diana’.
Photo credit Mon Jardin & Ma Maison

I had the pleasure of seeing Nicholas Staddon, director of the New Plants Team at Monrovia, at the Northwest Flower & Garden Show in February. We got to talking about the fact that most gardeners were missing an opportunity by not using clematis as a groundcover in their gardens. I wondered if Linda Beutler, curator of the Rogerson Clematis Collection in Lake Oswego, recommended certain varieties as groundcovers. Here’s her response:

“We, that is the FRCC [Friends of the Rogerson Clematis Collection] display gardens, are growing hybrid clematis as groundcovers in several places, and they serve the function very well. There are also clematis species that occupy the ground-plane naturally.

In a woodland setting, ‘Bells of Emei Shan’, brought back from China by Dan Hinkley and subsequently given a cultivar name when agreement could not be reached over its true identity, prefers partial shade, and was found growing over a nurse log with root covered by moss. Great plant to add to a stumpery.

In full sun, say on a rocky bank where there is some, but not too much, supplemental irrigation, the hybrids of Clematis texensis, such as ‘Princess Diana’ and ‘Gravetye Beauty’ are great groundcovers, rumbling along and cruising over low mounding shrubs like cistus or manzanitas like speed bumps. They want good drainage, and will create billowing cascades when they’re happy. Clematis texensis is found scrambling over river rock in riparian zones, sometimes in the sun and sometimes in partial deciduous shade. It climbs easily, but in the wild often does not.

Most of the Atragene Group (hybrids of Clematis alpina, macropetala, koreana, and their cousins) are natural scramblers, and these too tolerate gravelly soil. Atragene is pronounced at-rah’-jen-knee. Digging pumice into the soil with them seems to meet their drainage needs, and they run along the ground or form a large mat, but will then climb when they meet a vertical challenge. Look for varieties like ‘Markham’s Pink’, ‘Bluebird’, ‘Brunette’, ‘White Swan’, really any of that group. At Sissinghurst Castle, the famous 20th century garden in England, they use Clematis alpina as a ground cover, and use Clematis macropetala in containers, draping down the sides of tall elegant urns which are used as sleeves for the utilitarian pots the clematis are actually planted in. In another month or so, visitors to the Rogerson Clematis Collection at Luscher Farm will be able to see these plants in bloom and growing in an area called ‘Via Atragene”, where the plants have an option of mounting a Viburnum tinus hedge or meandering along the low rock wall and the base of the hedge.”

Thank you, Linda! The Rogerson Clematis Collection was formed over a long period with an eye to preserving historic clematis as well as the newest. The collection includes plants that are unique or exceptionally rare. At approximately 500 taxa and just under 900 individual plants, it is one of the largest assemblage of clematis in the Western Hemisphere. Approximately 30% of the taxa in the collection are not currently available in the “trade.”

To “bond” with one of the plants in the collection, FRCC started an Adopt-A-Clematis program. It allows “foster parents” to contribute directly to the care and feeding of one particular clematis plant for one year. Click here for more information on the Adopt-A-Clematis program.