By William Scheick Contributing Editor |
In introducing a new “super easy, super fragrant and super colorful” clematis, the authors of the most recent (and beautiful) catalog from Spring Meadow Nursery make a sobering admission: “Clematis has a reputation for being difficult.”
Perhaps we should expect that from a plant crowned as the “queen of vines.” Perhaps regality, even among plants, exacts a certain levy.
PARENTAGE CHALLENGE
Is it true that clematis can be difficult? The answer is yes, sometimes, but the reasons why vary.
One obvious reason is our perennial temptation to fall for lovely blooms without learning about a cultivar’s parentage (origin) or local sustainability. Most Texas gardeners, for instance, would benefit from being able to avoid clematises requiring a winter dormancy period, including snow cover.
Requisite snow-cover is not the only issue to know about beforehand. Consider, for a different example, Clematis x cartmanii ‘Blaaval,’ trademarked as ‘Avalanche.’ With hard-to-resist, yellow-buttoned, snow-white flowers, it has been available at various plant outlets in our state for many years. Even so, it is hardly ideal for Texas. Although this evergreen hybrid is cold hardy to 10–15º F, its parents are two New Zealand natives (C. paniculata and C. marmoraria), both accustomed to ample rain. Sure, with plenty of attention, particularly regular watering (think: reserved rainwater) and part-shade positioning, ‘Avalanche’ might serve as a container plant in our state.
Still, keeping the potted roots of ‘Avalanche’ or many other hybrid clematises cool enough can be a challenge. Clematises, in general, germinate in the shade of other plants onto which they eventually climb, and so their roots are accustomed to coolness. It is hard to maintain this coolness (thick mulch helps!) given our Texas sun, heat, wind and drought, all of which can impede or noticeably damage clematis flowers. And in our efforts to deal with this, we also run the risk of clematis crown rot from too much watering.
Unfortunately, getting helpful background information about clematis parentage or origins is not always easy. Even experts grumble about the consequences of such gaps in disclosure. Raymond J. Evison, author of Clematis for Small Spaces, once “desire[d] to acquire every newly introduced cultivated variety of clematis.” Not anymore, he has reported: “I am afraid that I am rather critical of many [clematis cultivars] that have been recently raised and introduced to gardens, because in my view they do not meet what I consider to be the real requirements for a good plant.”
PRUNING CHALLENGE
Another difficulty can stem from uncertainty about how or when to prune clematis. Richard Hawke, who since 1990 has evaluated more than 200 clematises at the Chicago Botanic Garden, acknowledges that clematis pruning “may seem a daunting exercise, even to an experienced gardener. A mystique has grown up around the pruning process, creating a perception of difficulty that is mostly unwarranted.” Note the hedge-word “mostly.”
With clematis, successful pruning is determined by bloom period. There are three categories. As Evison has succinctly noted, “early-season-flowering clematis [group 1] all flower on old wood, while midseason-flowering clematis [group 2] flower on both old and new wood, and late-season-flowering clematis [group 3] flower on new wood only.” Knowing which branches to prune and when to cut them makes a big difference in floral performance. As an aid, Clematis on the Web (http://www.clematis.hull.ac.uk/new-about.cfm) provides an excellent resource identifying parentage (when known) and also pruning group affiliation. Book-loving gardeners, like me, might enjoy digging for help in An Illustrated Encyclopedia of Clematis (2001).
FLOWER CHALLENGE
Clematises tend to be heavy feeders. Building up carbohydrates to trigger prolific flower production requires plenty of nutrients. So timing is important. Err, for instance, by feeding clematises already in bloom and their flowers will likely abort. In his chapter in Flowering Vines: Beautiful Climbers Hawke recommends fertilizing clematis yearly “in early spring before flower buds start to swell.” He further advises plenty of “organic compost or rotted manure” as “an ideal fertilizer” that “also acts as a mulch to retain [soil] moisture and cool the root zone.”
Hawke’s rating of 110 clematises is available online (www.finegardening.com/item/22996/clematis-trials-at-the-chicago-botanic-garden). Although he personally loves the big-flowered clematis queens, his ratings reveal that the smaller-flowered clematis princesses often score considerably higher. All things considered, including the proneness of some big-flowered clematises to mildew or fungal wilt as well as to a fatal heat-induced hyper-production of flowers in our state, Texas gardeners will probably find the smaller-flowered princess vines far less temperamental than the larger-flowered queens.
In her 2008 Organic Gardening report on clematis, Therese Ciesinski has maintained that too many of the over-bred large-flowered clematises are fragile and “have given clematis a reputation for being difficult.” In contrast, “what the small-flowered types lack in size, they make up in number; a single vine can bear hundreds of blooms.” And, Ciesinski wrote, they can be “as tough as daylilies.” Also smaller-flowered clematises can be easily managed to climb onto structures or scramble onto shrubs without threatening the viability of such supporting plants.
TEXAS CLEMATIS PAYOFF
Some dainty Texas native clematises are much easier to live with than the clematis queens. Gardeners with wet soil or moisture-retaining rich soil in East and Southeast Texas can grow a short-vined local perennial known as curl-flower, blue jasmine or hyacinth vine (C. crispa). When water is available, its upside-down purple-pink floral bells “ring” from spring through fall on five-foot vines.
The clustered nodding blooms of purple leatherflower (C. pitcheri), a limestone perennial native to most of Texas, can be easily cultivated in our gardens. It blooms in May through August, can reach 10 feet or so in length and sprawls in a non-taxing manner.
With reddish downturned fluted floral urns, scarlet leatherflower (C. texensis) has found a market niche, especially with such cute hybrids as ‘Duchess of Albany,’ ‘Gravetye Beauty,’ ‘Pagoda,’ ‘Étoile Rose,’ ‘Sir Trevor Lawrence’ and particularly elegant, tulip-like ‘Princess Diana.’ However, this Hill Country perennial is apparently not as garden-easy as purple leatherflower — perhaps because in the wild it crawls over boulders near water and is particularly responsive to rain. Some Texas gardeners have reported that scarlet leatherflower performs only fairly well in cultivation, an observation that seconds my own haphazard experience with it. While in his clematis trial results Hawke assigned low scores to several C. texensis hybrids, he praised ‘Princess Diana.’
For a surefire success, there is desert clematis vine (C. drummondii), which populates Central Texas and the South Texas Plains as well as stretches westward through the Trans-Pecos. In my Oak Hill neighborhood it voluntarily and harmlessly drapes wild shrubs. Also known as old man’s beard, virgin’s-bower, love-in-the-mist and barbas de chivato (goat’s beard), its non-petalled flowers may be small, but they also tend to be prolific along extensive twining vines ranging from 15 to 25 feet.
Viewed up close, the male flowers of this clematis look like petite sea anemones. Their tiny “polyps” are actually stamens surrounded by four pronounced cream-hued sepals that look like (but are not) inch-long petals. The female stage of flowering produces silky-haired elongated styles looking like wind-blown cotton candy.
This clematis is a drought-tolerant and freeze-resistant perennial that seeds copiously — four facts to keep in mind before inviting it into your landscape. Genetically designed for survival, it is a rapidly spreading, aggressive native that will likely extend beyond the rocks, fence or post it was planted to cover. Seed collection for this clematis should be postponed until the heads are dry but still attached to the plant. The seeds in these heads, Jill Nokes has advised in How to Grow Native Plants of Texas and the Southwest (available online at www.texasgardener.com), should be harvested when they are no longer green but also not yet completely dried to the point of falling to the ground.
WORTHY HYBRIDS
If our native clematises seem a bit too non-regal, there are hybrids worth trying. The smaller the flower, in my opinion, the better the likelihood of success in Texas. Cultivars in the Italian Viticella Group include many heat-tolerant clematises. Even so, there is no guarantee based on parentage. ‘Pagoda,’ for instance, is a hybrid cross between heat-enduring C. viticella and Lone Star native C. texensis; nevertheless, it is not considered highly vigorous.
One of the best among the Viticella Group is ‘Madame Julia Correvon,’ a gorgeous classic clematis which adapts to a wide variety of soils. It produces four-inch, reddish, semi-nodding blooms during the summer. In Hawke’s trial ratings, it received the highest possible scores. In my experience, though, even the flowers of ‘Madame Julia Correvon’ will show damage if the plant’s soil gets too dry — in short, a typical clematis response.
The four-inch flowers of ‘Ernest Markham,’ which also adapts in a variety of soils, did a little less well in Hawke’s ratings. Still, it received an excellent score for flower production. It is commonly available at Texas plant outlets. A combination of two pruning-group techniques — too complex to detail here — can get this plant to extend its floral production.
Clematises with five-inch flowers that are available at local nurseries and that also survive Lone Star conditions include ‘Rouge Cardinal,’ ‘Jackmanii’ and ‘Harlow Carr.’ Moving to six-inch flowers is probably pushing your luck in most of our state, but ‘The President,’ ‘Bees’ Jubilee’ and ‘Nelly Moser’ are respectable candidates that, similar to the mentioned five-inchers, have records of success in most of Texas.
In case you’re wondering about that new “super easy, super fragrant and super colorful” clematis noted at the start of this article, its name is ‘Sweet Summer Love.’ It is a striking short and slender-vined plant with a cherry-vanilla fragrance. This cranberry-violet flowered hybrid is based on sweet autumn clematis (C. terniflora), which is a naturalized plant in Texas. For Texas gardeners that parentage is good news because, as Skip Richter noted in Texas Gardener (July-August 2006), sweet autumn clematis is “dependably hardy throughout the state” and “does best in the eastern half.” Sweet autumn clematis is often invasive, though. Even so, the cold-hardiness and the heat-zone rating of its hybrid sibling make ‘Sweet Summer Love’ a possibility for most Texas gardens. It should be available at outlets carrying Proven Winners plants.
