Climbing or clinging, Clematis can brighten any garden and, when combined with suitable companions, take the vertical garden to new heights.

Clematis Arctic QueenT Evitwo (N)
Photos by Raymond J. Evison unless otherwise noted.

Today the nurseryman/grower is faced with a large selection of clematis to select from and grow for today’s garden center. The landscape market is also faced with this increasing list of new cultivars that come onto the market annually. Some of these clematis are put on the market just because they are new; some may not have been trialled at all as garden plants or – worse still – as production plants.

This article is aimed to help the nurseryman/grower and the landscape designer/contractor select the best clematis for the job they are intended for. Today everyone must have value-for-money plants – a plant must really perform over the longest possible period. Therefore, the nurseryman must have chosen clematis to grow that have a good or possibly the best shelf life, giving them the longest window in which to sell the plants to the retailer, and the retailer having the longest possible time in which to sell the plants themselves. Landscapers also need the best-performance plants to give their clients the greatest satisfaction in their gardens or landscapes.

Gardening vertically – with a little help

Vertical gardening means climbing plants, but not just clematis growing by themselves. To get the best out of clematis, they need to be grown with other plants. Clematis love or insist on growing with a cool root run, thus shaded by other plants. If we take a lesson from nature, the best clematis species that I have seen in the wild in North America, New Zealand, China or Japan have planted themselves with their roots in the shade of other plants or under a rock, but have then found themselves a host tree, shrub or plant to grow in association with. This is nature’s combination planting!

And for the nurseryman retailer, this means double or triple sales as the consumer needs a host plant, shade plants and the clematis: linked sales, I believe.

Clematis RebeccaT Evipo016 (N)

What are we, therefore, looking for in a clematis that will meet the above criteria? A clematis with nicely shaped and colorful flowers, a longest possible flowering period, easy to grow and maintain. From the latest breeding programs from the clematis breeders, these plants exist and are becoming more readily available in North America. The clematis that I intend to discuss here are much more grower-friendly, and you do not have to take out the clematis reference books every time you need to know how to prune them. Due to their parentage and the sophisticated breeding programs, these clematis will flower almost from early summer until early fall and sometimes later, but resting in the high summer temperatures. They can all receive the “pony tail cut” by cutting down all stems to 6 to 9 inches above soil level each spring before full bud break.

Clematis Kingfi sherT Evipo037 (N)

Before selecting the clematis, consider which will look best in a garden or landscape growing in combination with which host plant. Also remember it is the dark blues, reds, purples and whites that do well in the sun, and this then leaves the planting of the pale blues, lavenders, pinks and cream-colored clematis to be grown for the shady part of the garden or landscape.

Six-foot selections

Therefore I will suggest some of the best performers, such as, Clematis Rebecca Evipo016 (N), a sumptuous red that is great with pale blue, cream or yellow-flowered hosts, and also for growing with golden or variegated foliage. C. Kingfisher Evipo037 (N) is an extremely free-flowering bright blue, ideal to use with roses of all shades and light foliaged hosts. It looks brilliant with gray foliage. C. Ice Blue Evipo003 (N) is outstanding for use in a shaded garden. It will brighten up a north-facing wall; its very pale blue/white flowers really blend with everything and it is very long flowering. These three selections grow and flower annually to 6 feet.

Clematis CherokeeT Evipo041(N)

Short and sweet

Some shorter growing clematis for the small garden that grow to 3 to 4 feet are ideal for growing up into the base of wall-trained shrubs, roses and other climbing plants. These can be pruned down to 6 inches each spring.

Clematis Angelique Evipo017 (N), is pale lilac, most suitable for brightening up a shady garden. Other fine choices are Chantilly Evipo021 (N), which blooms cream with hints of pink, and Cherokee Evipo041(N) with its fun, pink striped flowers that look marvellous when planted with companions that bear blue flowers or gray foliage.

Some like it hot

For the hotter spots in the garden, choose these that grow similarly: Cezanne Evipo023(N) features attractive, sky blue flowers; or Fleuri Evipo042, which boasts deep purple-red blooms. Parisienne Evipo19(N) sports mid-blue flowers with a red center; it is outstanding when planted with yellow, orange or purple flowers, and brilliant growing up the base of a wall or with a fence-trained rose of these colors.

Clematis Ice BlueT Evipo003 (N)

Another great performer is the dusky purple C. Picardy Evipo024(N), which never seems to stop flowering and is superb with pastel-colored flowers of any wall-trained climber.

Double your pleasure

Without doubt, it is the double-flowered clematis that sell the best in garden centers. They look dramatic in gardens and always catch people’s attention because of their very different flower shapes.

Clematis PicardyT Evipo024(N)

These clematis perform best if they are grown through other wall-trained hosts; this is because their flowers are rather heavy, especially when soaked with rain, and damage could occur. But when grown in the protection of an evergreen wall- or fence-grown host, the host gives protection to the flowers. Deciduous hosts also give plenty of protection and provide a good array of stems that the clematis can cling to, thus giving the clematis the support it needs.

Let us consider some of the better more modern double or semi-double cultivars that have already proved themselves.

The best white is certainly C. Arctic Queen Evitwo (N) with its fully double, late-spring and early-summer flowers to the semi-double, late-summer and early-fall flowers. The creamy white blooms sometimes have outer green sepals or are part white and green, which is most attractive. Useful for a shady wall or fence when grown with a host, it looks great with any color but especially good with pale-blue flowered hosts. Grows to 6 to 8 feet.

C. Crystal Fountain Evipo038 (N), a plant I found in 1994 in Japan, has a stunning flower with pale, mauve-blue outer sepals and a spiky center of petaloid stamens. It is superb planted with gray- or purple-foliaged hosts at the base of red- or yellow-flowered roses. It grows only to about 6 feet, but it’s a plant that performs. Without doubt, this is a class plant that meets all the criteria I wrote about earlier.

C. Empress Evipo011(N) is almost a pink version of Crystal Fountain Evipo038 (N): A very dramatic flower, but possibly less free-flowering than the latter. It is stunning with pale-blue flowered hosts, or again when grown with purple foliage hosts, growing to 6 feet.

Clematis Crystal FountainT Evipo038 (N)

Although introduced at the 1998 Chelsea Flower Show, Josephine Evijohill (N) is still a relatively unknown plant, yet a mass seller. Its double flowers are a pinkish mauve with larger outer sepals and a pom-pom like center. It flowers extremely well even in the high temperatures of the Oregon summers. Its flower color lends itself to be associated with any host flower color; possibly best, however, when not grown on a north-facing wall or fence, as its spring flower color could become less vibrant.

These double and semi-doubles need a slightly different pruning requirement to the previously mentioned single-flowered clematis, as they flower from both old and new growth stems. At the end of winter, or early spring before full bud break, just reduce the top growth by 33 percent to 50 percent, taking out any weak stems.

Clematis JosephineT Evijohill (N)

The above-mentioned doubles are superior to the older doubles, which only produce double flowers on the old ripened stems. These newer selections will bloom with double flowers from the current season’s stems, even after a severe winter when top growth may be killed to the ground.

Raymond J. Evison
Photo courtesy of The Guernsey Clematis Nursery Ltd.

Their feeding is so straightforward: Just use tomato or rose feed, but remember they need to receive plenty of water through dry summer weather. These clematis are all winter hardy (zones 4 to 9) as garden plants.

The above is a glimpse into some of the more recent clematis with class and performance, that are outstanding production, retail and garden plants that should be grown more widely, which will bring you added profits and satisfaction, I am sure.

Ramond J. Evison OBE VMH (Officer of the Most Excellent Order of the British Empire, Victoria Medal of Honour from the Royal Horticultural Society) is founder and owner of The Guernsey Clematis Nursery Ltd., located on the Isle of Guernsey, one of the United Kingdom’s Channel Islands. He has introduced more than 100 species and cultivars worldwide, serves as vice president of the Royal Horticultural Society, and is author of several books, including Clematis for Small Spaces.