Clematis is a diverse genus of flowering vines. While there are some monsters that will grow twenty to thirty feet of stems in one season, others will remain at a petite eight to ten feet tall and are suited for container gardening.

My favorite clematis expert is Portlander Linda Beutler, whose book Gardening with Clematis: Design and Cultivation is filled with terrific tips and tricks especially suited to Northwest gardeners for getting clematis to perform at their best. After reading her book and hearing her speak at gardening workshops at the Camas Public Library and Joy Creek Nursery, I decided to give container-grown clematis a try for myself.

To begin this gardening adventure, I started discovering plants that will thrive within the constraints of a container. I've had good luck so far with three large-flowered hybrids. The first is "Asao," which has darkish pink blooms accented with lighter pink centers and which blooms early in the season, from the end of April until the end of May. Linda advises that if you sparingly prune off the dead ends and fertilize it at half strength right after it finishes its first bloom, it will often rebloom for the month of September. This clematis doesn't need any hard pruning to keep it in full fig, just a light trim to keep it neat. 'Asao ' is quite happy in my garden growning in an eighteen-inch tall and wide turquoise-blue plastic pot along with the October through February-blooming double soft pink Camellia sasanqua 'Jean May.' 'Jean' stays much smaller than her later blooming, sometimes tree-sized, Camellia japonica cousins. Because this evergreen camellia is more shallow-rooted than the clematis, it is happy to spread its roots near the upper portion of the pot while the clematis burrows its roots deeper down in the pot, thereby cooperating in limited quarters. I also like to add some shallow-rooted annuals, including summer-blooming pastel sweet peas and baby-blue 'Cambridge Blue' lobelia with a dark purple, fragrant heliotrope to the mix to create a container that has something of interest going on four seasons of the year. This pot thrives in a covered entryway to the house so that harsh winter rains don't crush and dissolve the somewhat tender camillia blossoms.

Two other of my favorite clematis for containers include the double purple 'Daniel Deronda,' and the double pale lavender 'Louise Rowe.' Both 'Daniel' and 'Louise' flourish under the same regime of pruning and fertilizing that I use with 'Asao,' and both bloom at about the same time as 'Asao.,' 'Daniel' is wonderful growing up through something yellow or chartreuse. I placed the container so it grew near a large yellow David Austin English rose 'Graham Thomas,' with some airy, five-foot tall Verbena bonariensis rising up on pencil-thick stems as a purple haze. In a container setting, you might select a diminutive chartreuse-foliaged shrub in a neighboring pot, such as the small, two-foot tall and wide evergreen Hebe 'Co-ed,' with chartreuse foliage maturing to green, and purple summer flowers. Another colorful choice would be the two-to-three feet tall Berberis thunbergii "Aurea Nana,' with golden foliage, mid-spring yellow blooms and red berries in the fall.

'Louise' is a fascinating clematis to watch over the growing season, because it can simultaneously have single, semi-double, and double flowers in bloom. Her flower color is set off by close proximity to the color blue, perhaps used as the color of the container in which she grows, which is what I did, or accomplished by growing other blue-flowered or -foliaged plants close at hand. One that I like is Cerinthe major 'Purpurascens.' An annual that reseeds rather freely in my garden, it has blue-green leaves on arcing stems, and at the tips of each stem flowers a small tubular dark purple blossom. It looks great combined with that stalwart and infinitely blendable annual, lacy Dusty Miller. Both annuals keep their good looks from spring through fall, helping not only to intensify the clematis flower color but also to carry the container over while the clematis is in-between first bloom and rebloom.

True to their vine nature, pot-grown clematis need some kind of structure upon which to grow. I met this need by placing my containers near structures upon which the plant could grow, such as a large rose and a handrail and spindles. If you wanted a freestanding container, you could use a narrow piece of trellis at least twice the heigth of the pot and eight to ten inches below the soil surface to anchor the structure. Trellis can be purchased, or homemade out of wood, copper tubing, even painted one-half inch PVC pipe connected with appropriate fittings. Clematis will need to be tied to any supporting surface diameter greater than one-half inch. You can wrap larger supporting posts with chicken wire and the clematis should be able to climb up the structure on its own, with just a little help from you in the form of attaching it with twine while the plant is young.

Because these vines will be living in pots for several years, it's a good idea to choose high-quality potting soil. I succeeded with my three clematis by following many of Linda's tips on the best type of potting soil and planting method. She recommends looking on the label of the soil to see if it contains something to lighten the soil like sand or pumice, composted manure and worm castings, kelp meal, dolomite lime, bat guano and bone meal. If you make your own homemade compost, add some of that to the mix as well. Before filling your pot with soil, put some fine metal mesh in the very bottom of the pot to cover the drainage holes so the soil doesn't run out, next a couple of inches of gravel for good drainage, then add soil mixed with a sprinkle of slow-release fertilizer about halfway to the top, after which you can place your new plant into the pot. You want to cover the root ball plus about three inches of the stems. Adjust the soil level so the plant is at the appropriate depth, insert whatever supporting device you chose to use, then fill in the container with more of the potting soil until you're within a couple of inches of the top of the pot. Water at this point, allow the soil to settle, and add soil as necessary so the soil level remains at a couple of inches below the top of the pot. Tie the clematis to the structure, then finish with a thin top layer of gravel for a mulch. For maintence, iIt's best to water every one to three days depending on how dry it is. Linda also recommends that six weeks after you pot up the clematis you should start using flower-boosting fertilizer about once a week until the plant has set bud, then stop fertilizing until after it has finished blooming and you're preparing it for fall rebloom.

If you're like me, you will quickly become enamored of these amazing vines, and you will be well on your way to enjoying dapper spring and fall-blooming clematis that may well be the abundant showpiece of your container garden.

All content copyright 2007-2011 Minerva's Garden