One of the questions most often asked at the garden center relates to the pruning of clematis vines. It can be a somewhat confusing topic. This confusion arises from the fact that there are different types of clematis, each requiring different pruning styles. Within the three pruning categories, botanists break things down into sub-groups and the waters become even muddier. Considering that there are hundreds of available varieties of clematis, the topic can get quite overwhelming for the person who just wants a pretty rambling vine to grow over the walkway arbor.
Let’s see if we can simplify the subject:
These are varieties that flower early in the season on the previous year’s growth. This group includes the popular evergreen, Clematis armandii, and the equally popular Montana varieties. These should be pruned within about a month after they are finished blooming. They can be pruned back to shape and thinned out to prevent the vine from becoming a big tangled mess over time. Shape the lateral growth back to the main branches. Pinching hard some of the low growing branches will prevent the vine from becoming bare at the base. Use a nice mild organic fertilizer at this time if you think it needs it.
The classic summer bloomers usually have huge blossoms, which flower on wood produced in the spring. These will usually bloom through the summer and into the fall and are generally the easiest to prune. This type of clematis will take on a somewhat dead look when it is done blooming. General rule: If it’s ugly, cut it back. Cut them back to about two feet from the ground as part of your fall clean-up routine or wait and do it in early spring if you don’t mind looking at the dead bits through the winter. The time to fertilize this type is early spring as the vine is breaking out of dormancy.
This is the most confusing group, but also very desirable as they bloom twice in the year. Normal blooming patterns are expressed by a heavy flush of flowers in May-June on the previous year’s wood, followed by a seco9nd bloom period in September on the current season’s growth. With some varieties in this group, the first flush of blooms display large, showy double flowers, while the second flush has smaller, single flowers.
In pruning this type, the old wood should be preserved by pruning lightly in fall or winter, removing only dead wood or weak, spindly growth. In spring, right after the bloom is finished, cut back the branches that flowered. This promotes the new growth that blooms in the fall and then grows on to become the old wood, which blooms the following spring. (Whew! Got that?) You end up pruning these types twice a year and you get to look at dead ugly wood through the winter, but you get two resplendent bloom displays each growing season. If you buy this type of clematis and then decide to be lazy and not prune them, you’ll generally have a lot of rampant growth and a few flowers, but nothing as magnificent as if you do the correct pruning.
If you plant a new clematis vine and it suddenly wilts before it really takes off, do not assume it has died. This is a problem known as “clematis wilt” and is a very common occurrence. Cut the whole thing off to about the second bud. New growth will come up from the base. Keep the slugs and earwigs away until it is up and running. Clematis will respond to lots of good organic fertilizer and water, but cannot tolerate poor drainage. Give each vine at least four or five hours of sun a day and keep the roots cool. They are somewhat fragile getting started, but once it finds its feet, the clematis vine is practically bomb-proof.
One more thing . . . if you want to pronounce “clematis” correctly, put the emphasis on the first syllable.
“Because it climbs upon a lattice, Hoi polloi will say “clem-at’-is”, But Webster will not cease to hiss, Until they call it “clem’-a-tis.”
Maureen Murphy, Bayview Farm & Garden
Clematis lanuginosa, chromolithograph by Louis-Aristide-Léon Constans, from the third volume of ”Paxton’s Flower Garden” (1852-1853) by John Lindley and Joseph Paxton.
Clematis jackmanii, By Scott S Emberley (Own work) [CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons