Clematis

WHEN WE TALK ABOUT SPECIES CLEMATIS, (or clematis species, for they are the same thing) in a gardening context, we mean those clematis with usually quite tiny flowers, most of which are species, though some are crosses resembling species. The fact that the species’ flowers are small compared with the large-flowered clematis by no means lessens the display, because the smallness is compensated for by far greater numbers, although the impact is of a different kind. Big and blowsy is fun in its way, but "small is beautiful" has its own appeal (as also in the world of business). The species also often have qualities, notably fragrance, that are quickly lost with hybridization.

Clematis viticella, C. campaniflora

 

Take the south European species Clematis viticella (USDA Zones 5-9), for example. Its purple lanterns are held out from the plant on long, dark, threadlike stalks. They hang demurely and are best seen from above, where the strongest coloring is. None of the numerous hybrids of which C. viticella is an antecedent have this grace. Their flowers always look you boldly in the face. There’s nothing wrong with strong statements in the garden, but there is a place for modesty as well.

I must add, however, that C. viticella is a variable species and that some of its representatives can be a little too mousy for garden purposes. I have been lucky, however, and have an excellent strain that I raised from Thompson & Morgan seed. It grows alongside Hydrangea aspera Villosa Group, which flowers at the same time, in August, and is of much the same coloring, though of a slightly lighter shade. So the contrast is more in form and habit, with the clematis threading its way through the hydrangea. This is a very subtle effect, and the trouble with such subtlety is that almost no one notices it unless you point it out to them. Which I do, constantly, of course.
White-flowered species have great impact in a garden setting, because they hail you from a distance. Closely related to C. viticella is the Portuguese C. campaniflora (Zones 7-9). Its pendent bells are smaller than those of C. viticella, but, being white (with just a hint of blue), they show up well. The plant is vigorous, and a well-flowered specimen is a delight in its August season. I wish I didn’t have to confess that, although mine grows rampantly, it produces only a scattering of blossom. We have lately moved it to a new location. This is the thing to do in the circumstances.

Natural supports for clematis

It is well known that clematis like to climb through and over other shrubs, but the type of shrub is important. It should be stiff of habit, either naturally, like many rhododendrons and lilacs, or because of regular pruning. I have, for example, a Mahonia media ‘Buckland’. Mahonias in this group can become excessively stemmy, exposing a lot of bare wood if left unpruned. So I prune mine, shortening back the flowered shoots every spring. This has made it a very solid unit, ideal for taking the weight of a clematis.

Another way to mitigate the weight of a clematis is to knock in a stout stake alongside its host. This can then take the main weight of the clematis, while some of it is allowed (that is, carefully trained, but without any contrivance being apparent) to meander negligently over the host shrub. -C.L.

Clematis terniflora, C. paniculata, C. maximowicziana, C. flammula, C. recta, C. finetiana, C. armandii

Most of the white-flowered species have cruciform flowers -four sepals arranged in the form of a cross. I have enjoyed seeing one of the showiest of them, C. terniflora (Zones 6-9), in New England gardens in late September, bursting with abundant blossoms. (This Japanese clematis has also been known as C. paniculata and C. maximowicziana.) Farther south, it flowers earlier, but in England it is apt not to flower at all before winter’s onset. However, there must be many different clones, some more precocious than others. My first try with C. terniflora was a washout; I must try again. It is creamy white and the flowers are not too wee, so it makes a great display, though I do not detect much scent.

I have had much better success with C. flammula, which you meet in the wild, scrambling about on hot hillsides in Provence. It doesn’t show much propensity to climb there, and in the garden I am happy to see it cascading out of a raised container. We have some old, brick, cattle-drinking tanks, which are ideal for the purpose. One of the nice bonuses about this species is the light-reflecting gloss on its leaves. It flowers for us in August (probably a month later than in much of the United States) -a huge foam of tiny, white, cruciform flowers, wonderfully scented on the air. It is a slightly sickly scent at close range, usually compared with hawthorn. Such scents are unwelcome in hospitals (where hawthorn is banned) but fine in the garden. Clematis flammula is moderately vigorous and comparatively short-lived. If it gives you eight or ten years, you’ve done well. You can grow it from seed, which generally takes 18 months to germinate. It is hardy only to Zone 7.

The herbaceous C. recta (Zones 3-9), from eastern Europe, is thoroughly hardy. It carries a billowing cloud of white, cruciform flowers each June. The flowers have little scent but are good for picking during their brief June season. The seed heads, moreover, look nice after flowering. Alternatively, as soon as the display finishes, I cut all the flowered stems back to just below where their flowering started. Subsequent growth will (if kept free of mildew) provide a worthwhile second flowering. The purple-leaved form, C. r. ‘Purpurea’, is richly colored early in the season to the extent that it is really not worth growing the plain green plant. The one snag about this clematis is its floppy habit. Clematis recta could scarcely be less erect; we construct a cage of brushwood more than six feet high to support ours.

My greatest success with these cross-flowered clematis has been with an evergreen Chinese species, C. finetiana (Zones 8-10). This is as vigorous as C. armandii and quite as hardy. The foliage is far more elegant and its flowering -on young growth of the current season- occurs in mid-July. The flowers last for just two weeks. But they are two weeks of intense pleasure, not just because of the abundant display but also because of the huge gusts of eau-de-cologne scent, which are wafted halfway around the garden. 

Clematis montana, C. jouiniana, C. eriostemon

Clematis montana (Zones 5-9) has four sepals, and the flower may be three inches across, though with gaps between the sepals. By definition, C. montana is white, the pink-flowered forms belonging to its variety rubens. Clematis montana has destroyed the roofs of several outbuildings at Dixter in my lifetime, so I am chary about where I site it nowadays. It makes a good companion for Jasminum officinale f. affine (the larger-flowered variety), both being of roughly the same great vigor but flowering at different times -the one in May, the other in July-August.

The strong vanilla scent, typical of C. montana (mine have no clonal names), is not always present in this species, so it is a point to look for when making a purchase. The scent is strongest toward the end of each flower’s blooming. The pink-flowered C. m. ‘Elizabeth’ is a reliably well-scented clone.

Clematis montana, which normally flowers in May, is the most vigorous of all clematis, the only one that it is fair to expect to cover a tree (though not one larger than an apple or pear). Remember that the color of white C. montana is just the same as that of pear blossom, and the pink C. m. var. rubens is similar to apple blossom. Since they may all flower at the same time, the difference between host and vine can well be blurred.

I have a pink-flowered form of this clematis called ‘Continuity’, which only starts flowering just as the main crop (whose season is quite short) is going over. But ‘Continuity’ continues to produce waves of blossom through most of the summer. Its flower stems are unusually long, so the blossom is handsomely presented. I have it growing over a golden conifer (and probably killing it). I dare not examine the situation; living in a fool’s paradise is so much better than no paradise at all.

It is some of the larger-flowered clematis that give us best value in terms of length of season. One with sizeable yellow bells, called ‘Bill Mackenzie’ (Zones 6-9), is exceptional in this way. Its parents are probably C. tangutica and some form of what we used to call C. orientalis, now C. tibetana subsp. vernayi. ‘Bill Mackenzie’ is pretty vigorous, growing to 15 feet. If you prune it lightly, it will start flowering in June and will continue into October, the later blooms being joined by the fluffy gray seed heads from earlier flowers.

Clematis are willing assassins. In my garden, ‘Bill Mackenzie’ is killing an espaliered pear. But you don’t have to worry too much about this kind of thing. All life is a struggle. As long as your plants look happy together, and as long as you are aware of what’s going on and refrain from moaning when it’s too late anyway, your gardening shouldn’t and won’t promote an excess of anxiety.

Some rather nice species clematis have no climbing devices. Clematis jouiniana (Zones 5-9) is a case in point. It is a hybrid between C. vitalba (which is native to Britain) and the herbaceous C. heracleifolia var. davidiana. Although more than half of its voluminous growth dies back in winter, it makes excellent groundcover. Or, if you care, as I do, to give a lift to its uniform flatness, you can tie some permanent shoots to a pole or train and tie them into a wall. Another way you can give a sense of height to its vast apron of growth is to interplant it here and there with a tall, contrasting perennial. I use Helianthus salicifolius, not for its flowers, which are produced very late anyway, but for its columns of narrow, papyrus-like leaves.

Clematis jouiniana has pale, skimmed-milk-blue, cruciform flowers in great abundance. In our climate, we get better value from the clone ‘Praecox’, which flowers from July to late September, than from the original cross, which doesn’t get going till late September, and therefore has a curtailed season. With the hotter summers experienced in much of the United States, this preference would not apply.

Another nonclimbing species that I am fond of is C. eriostemon (Zones 3-9), which has the honor of being the first recorded clematis hybrid, the offspring of C. integrifolia (an herbaceous European species) and C. viticella. It was introduced in 1835, but the same cross has been made on a number of occasions. Clematis eriostemon is herbaceous, but it can make several yards of growth in one season. Its nodding, bell-shaped flowers are deep indigo, borne over a long summer’s season. It is tough, and I grow it in rough meadow grass alongside the vigorous, red-and-purple Fuchsia magellanica ‘Riccartonii’.

I have only scratched the surface of a big subject, but it will be seen that clematis species offer us gardeners many opportunities to experiment.

Christopher Lloyd is a regular contributor and the author of numerous books, including Other People’s Gardens (Viking, 1996).

See our September/October 2002 issue for A Gift of Clematis – Poland’s Brother Stefan Franczak has created a new generation of outstanding hybrids.

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About Amanda Thomsen

Big, loud and fun- Amanda Thomsen landscapes by day and blogs at night. Her blog, Kiss My Aster, on Horticulture magazine's website has alienated/enraptured dozens. She co-authors a blog called Plants That Suck that is about plants that suck. And she is the less popular half of the podcasting team, Good Enough Gardening, which makes her feel like the "Roy" of of Siegfried and Roy, but without the mauling. She lives in Chicago and does not EVER put ketchup on hot dogs.

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