In my new garden I have managed to find homes for 11 different clematis vines, so far anyway. I planted one each on the 4 posts of my pergola on the east side of the house two years ago and they are all coming back like gang busters. Last summer I planted another 6 against my south fence on three 4 by 8-foot galvanized panels attached to the north side of the fence. They did okay and all are coming back, with the exception of one, which wilted down last summer and never recovered. Not a bad record overall. When I picked out the various varieties, I wasn’t thinking about how I would have to prune them. Rather, I was mostly looking for summer bloomers with flower color, with the exception of one spring bloomer, an ‘alpina’ variety called ‘Stolwijk Gold’ which sports yellow foliage with dainty blue flowers.
In March of this year, I took a hard look at the dormant vines and attempted to do some cleanup before they started to put on new growth. Since they are all relatively young plants, I decided to go easy and leave most of last year’s growth, unless it was perfectly clear that it was dead. I will watch them closely this season and adjust my pruning regime next winter to better manage them. However, if they had been well established, this is how I would have pruned them…
Clematis vines fall into 3 general categories when it comes to pruning.
Group 1 consists of vines that only bloom on last year’s growth (or old wood). This includes the ‘alpina’ varieties like my “Stolwijk Gold, ‘montana’ varieties and the evergreen variety ‘Armandii’. These vines only bloom once in spring, so if you need to rein them in, prune them back hard after they finish blooming. If, on the other hand, you want them to cover a fence or arbor, then just let them keep growing.
Group 2 consists of vines that bloom on both old wood (last year’s growth) and new wood (current season’s growth). I tend to think that just a light pruning in late winter is best for these types. You will get nice big flowers in May and then a second flush in late summer. If the vine is getting too rangy, either cut it back hard in spring and sacrifice those May flowers or whack it back after the May flowers fade and plan for a delayed bloom in the fall.
Group 3 are varieties that only bloom on new wood. These are easy because all you have to do is cut the entire vine down to 6 inches or so from the ground in the spring, before they start to grow, and they will start blooming, usually after June, and then continue to do so all summer long. I have a ‘Princess Diana’ on a separate trellis that does this and it is one of my favorites.
If all of this is just too overwhelming, you might try some of the newer more compact varieties, like the ‘Vancouver Series’ from Monrovia which only grows to around 6 feet tall. Since they are in Group 2, they will still benefit from some light pruning.
Most vines are considered vigorous growers and benefit from some form of pruning. Wisteria, Honeysuckle, Trumpet Vines, Passion Vines, and the like all look better if they are pruned to keep them in scale to the landscape and to manage flower production. You can usually let them go for a few years, but eventually, some degree of renovation and rejuvenation will be needed. As for your Clematis, pay attention to where the blooms are formed and that will be your clue as to what group they fall into. Once you have established their group, you will know what to do. Wishing you happy discoveries in the Clematis world!