More On The Climbing Clematis

Last week we began taking a look at the climbing vine clematis (see the online version for the full text) and I mentioned that there are some new varieties that are about to shake up the clematis world, and maybe your garden, patio or planter.

While there are about 20 or so varieties that you can find at local garden centers, there are upward of 200 clematis vines that you can buy from specialty growers such as clematisnursery.com and donahuesclematis.com. A few have been “invented” or hybridized right here in the States and a few have snuck in from Eastern Europe but the vast majority of the recent introductions are coming from the British grower and hybridizer Raymond Evison.

Mr. Evison has premiered a host of his new introductions, some of which were developed in conjunction with Danish nurseryman Poulsen Roser. At the Chelsea Flower Show in England last year, Mr. Evison showed an astounding 2,000 plants that spanned his more than 30 years of work. This year, he’s presenting at least 10 new varieties. But what’s really exciting is that he’s now got a stable of clematis that are perfect for those of us who may be intimidated by 15- to 20-foot vines that can get destroyed by our oft manic winds.

Mr. Evison’s new short and compact vines seem to be perfect for patios, planters, deep window boxes and balconies, as well as in the garden. Many of his introductions are available only from specialty growers, though I was in a Southampton garden center last week where the manager said “Hey, we got these clematis and they’re new.” And sure enough they had the Evison name on the tag.

It may be a few years before we see his latest introductions on this side of the puddle, but keep your eyes peeled for Ooh La La, Cézanne, Parisienne, Picardy, Chantilly, Angelique and Fleuri—which all grow to about 4 feet. In the 6- to 8-foot category, look for Josephine, Bourbon, Shimmer and Rebecca. There are also some doubles; in this group, watch for Arctic Queen, Josephine and Diamantina. Mr. Evison also has a number of books on the subject, so if you’re looking for a reference, check out his titles.

Grown in tubs and planters, many of these plants make excellent terrace or patio plants. Tubs should be at least 12 inches in diameter and 12 to 18 inches deep. Remember that these plants need good drainage so make sure that there are adequate holes in the bottom. If possible, the tubs should be shaded to keep the root cool while the vine itself grows in full to partial sun.

Soil mixes should consist of 50 percent soil (topsoil out of a bag is best) mixed with 50 percent peat lite mix, such as Pro-Mix. Add a time-release fertilizer to the mix, such as Osmocote and try to use 2- to 3-year-old plants.

Remember that these are vines. Know the habit of the variety that you’re growing so you can provide it with the proper support or trellis.

For outdoor planting, dig a hole 2 feet deep and 12 inches wide. The hole should be filled with a mixture of good loam mixed with peat moss. Be very careful not to twist or break the stem base where the roots are attached. Most important is to protect this area from direct sun, that is the bottom 3 inches of the stem after it is planted. A mulch of salt hay or pine needles will do, but it’s this step that is usually ignored and results in failure.

Remember to give the plants something to climb on. Give them something to attach themselves to or they will languish. They do not really twine, but climb by attaching their leaf petioles around some means of support like thin trellis, bamboo stakes or even wire or string.

In our greenhouse, we had a C. Florida that attached itself to the bench supports. And in the garden, one plant grew up and through a magnolia, another high into a hemlock hedge, a third up and along a yew hedge and yet another forms an umbrella-like spray up and through a wrought-iron dome.

There is also a native clematis (well, native to Pennsylvania) that may appeal to many gardeners, including those who like to go on the wild side. It’s called Clematis viorna, or leatherflower. It grows to 12 feet in length and has somewhat dainty but interesting flowers in shades of purple. It should be pruned to the ground once it’s completely dormant.

And speaking of pruning, this is where most gardeners go wrong with clematis. The plants are grouped into three pruning classes. Prune yours wrong and you can kill it or keep it from flowering. Send me an email and I’ll send you a simple sheet that describes each class and how to treat it.

Keep growing.