As a nursery manager I get to see a lot of people pondering plants, but by far the hardest decisions seem to be made in the clematis section. The difficulty choosing specific clematis can be attributed to a number of factors; including some confusion about pruning groups and a lack of clear growing parameters from the outset. Other dilemmas are the many options available out there (well over 200 species and about 400 cultivars) and the fact that it’s impossible for any one garden centre to stock all of them. What usually happens under these circumstances is that we either don’t find what we’re looking for or we have so many to choose from that we get confused. So to help you make the right clematis choice for your garden I’m going to break them down into easy to choose from groups.
Tree Scramblers & Fencing Screens
These are essentially the vigorous species and cultivars that one would choose to scramble up a leggy tree or cover a bare fence line. Your evergreen option is Clematis armandii with its glossy tapered leaves and fragrant white (‘Snowdrift’) or pale pink (‘Apple Blossom’) flowers. These bloom from March to April and quickly grow out 20-25’ at maturity. Clematis montana is your next best bet with massive clusters of white (‘Grandiflora’), pink (‘Elizabeth’, ‘Rubens’, ‘Tetra Rose’) or double blooms (‘Broughton Star’) from May to June, some of which are fragrant. With the exception of ‘Freda’ (12-15’) most are quite vigorous and can reach lengths of up to 30’. The fall blooming (Sept-Oct) species Clematis paniculata or Sweet Autumn Clematis is another good choice with its highly scented billows of small white flowers. Also blooming at this time (June-Sept) is the Golden Clematis (C. tangutica) with its nodding yellow blooms and silky seedheads on branches up to 20’, depending on the variety.
Gardening in pots does not mean saying no to Clematis, you just need to choose shorter-growing varieties and adhere to a few rules. Always use a large container (minimum size 2’x 2’ x 2’ deep) with an obelisk or small trellis for support. Make sure the drainage is adequate and shade the roots with perennials or seasonal bedding plants. Most of the Evison clematis have been bred for container culture, with the double flowering ‘Josephine’, ‘Reflections’ and ‘Empress’ being absolute show-stoppers, the two-toned ‘Picardy’ (4’ tall) quite floriferous while the tiny ‘Bijou’ (blue-mauve) and ‘Luiza’ (magenta) grow only 1’ tall by 2’ wide and can be accommodated in smaller containers. Standard varieties that also work well in pots include ‘Multi Blue’, ‘Piilu’ (semi-double), ‘Kilian Donahue’ (fuchsia and ruby), ‘Julka’ (purple with red vein) and ‘Westerplatte’ (deep red).
Left to Right - 'Josephine', 'Reflections' & 'Julka'
Left to Right - 'Killian Donahue', 'Luiza' & 'Picardy'
There’s a reason some varieties of Clematis have been in production for decades (or even over a century) and it is because they are generally free-flowering and disease resistant. The late 1800’s was where it all began with the introduction of such favourites as ‘Jackmanii’ (purple 1862), ‘Miss Bateman’ (white 1869), ‘Proteus’ (dbl. rosy-lilac 1876), ‘Ville de Lyon’ (carmine 1899), ‘Nelly Moser’ (two-tone pink 1897) and ‘The President’ (purple 1876). The 1950s saw another revival with ‘Lincoln Star’ (raspberry pink bar 1950), the vibrant ‘Mrs. N Thompson’ (violet with red bar 1954) and ‘Hagley Hybrid’ (shell pink 1956) newly released but quickly becoming garden favourites.
Far too often gardeners come shopping for one specific clematis cultivar in mind and often refuse to consider similar-looking varieties, some of which perform better. While ‘Nelly Moser’ is a popular cultivar, ‘Dr. Ruppel’, ‘Carnaby’, ‘Capitaine Thuilleaux’ and ‘Bee’s Jubilee’ all have a similar two-tone pink-white appearance and the same reliable performance. If you can’t find the deep purple ‘Jackmanii’ then consider the equally good looking ‘Warsaw Nike’, ‘Gypsy Queen’ or ‘Plum Gorgeous’, which is a part of the local Vancouver series. While ‘Henryi’ is an outstanding white, ‘Gillian Blades’, ‘Huldine’, ‘Guernsey Cream’ or ‘Fragrant Star’ all have pure white to cream flowers and make a nice addition to that perfect alba garden.
Blooms All Summer
Perhaps the most frequently requested attribute for clematis is that it bloom all summer, and this is where understanding the pruning groups can guide you. What you are looking for is either a C (blooms constantly on new growth) or B2 group (blooms on both last year’s wood and current season’s growth), as these will generally be in flower from June to September. Most two-tone or double forms are not included here but there are still many beautiful cultivars to choose from; including ‘Madame Julia Correvon’ (burgundy C), ‘Rouge Cardinal’ (crimson C) ‘General Sikorski’ (blue B2), ‘Niobe’ (wine-red B2 or C), ‘Polish Spirit’ (deep purple C) and ‘Ernest Markham’ (magenta-red C). Both C and B2 group clematis also work well in combination plantings (with honeysuckles, roses or other clematis) as they are cut down in late February or early March and make a fresh start every year.
Enjoying the Exotics
Exotic looking clematis are a mixed bag as far as hardiness is concerned. Both the ruffled petals of ‘Lord Neville’ and the luscious double blooms of ‘Vyvyan Pennell’ would work well in any tropical-themed landscape, but both are quite hardy at USDA zone 4. Similarly the unusual bell-shaped blooms of Clematis chiisanensis ‘Lemon Bells’ (zone 6) or Clematis texensis (zone 4) have a unique form but both are durable cultivars. However, the early blooming Clematis x cartmanii ‘Joe’ and C. cirrhosa ‘Freckles’ are stunning in flower but rather tender at USDA zone 7-8. Equally beautiful is Clematis florida ‘Sieboldii’ and ‘Alba Plena’ but since both of these are rated zone 7 they will need a sheltered microclimate to thrive, which is something to consider before purchase.
'Lord Neville' & 'Vyvyan Pennell'
There are a number of clematis species and cultivars that can be used as groundcovers, although I would consider these when trying to obscure the leggy base of a large shrub or small tree. Harry Potter fans will enjoy the pun of Clematis recta ‘Serious Black’ with its dark purplish-brown foliage sharply contrasted by the tiny pure white blooms. Another good choice is Clematis ‘Durandii’, a very old (1870) hybrid between ‘Jackmanii’ and Clematis integrifolia with recurved indigo blue flowers and a long bloom period.
'Serious Black' & 'Durandii'
Well that should give you enough to choose from for now, but to be honest we haven’t even scratched the surface of what’s available out there. In any case, I hope this helps you spend a little less time pondering your potential purchase in the clematis section.