By Cheryl Harrison, Master Gardener
I can not claim to be a clematophile (Clematis expert) but I do like Clematis! Clematis are wonderful perennial flowering plants … many grow as vines, some are more like small shrubs, some are evergreen and some are herbaceous so die back to the ground each winter. Their flowers come as bell-like or more star-like shapes with sepals that are single or double; some are scented. And the colours! They range from white or yellow to pink or red to purple or blue … pale to deep and some are even striped. Some flowers grow as large as 25 cm (10in) across! The beautiful clematis blooms are followed by eye-catching fuzzy seed heads. There are lots of choices in the genus Clematis.
Clematis grow in zones ranging from 3-11. If you are not sure which zone you are in, check here. Choose a plant from a reputable dealer. Look for those that have strong stems and are at least 2 years old so that their root structure is well developed. Most Clematis prefer sun or part shade but like their roots kept cool so mulch or plant another perennial close by to shade the roots. Plant your Clematis in moist but well drained soil with lots of well-rotted, organic matter (eg. finished compost) added. Plant the ripened stem (brown, no longer green) about 16 cm (6 in) below the final soil level. Clematis prefer neutral to slightly alkaline soil. All new plants need to be watered regularly until they are established and during dry conditions. Fertilize with an all purpose organic fertilizer monthly but stop when flower buds are ready to bloom in order to prolong bloom time. You may start fertilizing again after flowering has ended but stop feeding in late summer early autumn.
Pruning your Clematis for the best blooms may seem complicated. The confusing part for me was that some references refer to groups 1,2,3 and others use group A, B, C while others will use the species names. What is important is knowing what you have and then you can determine how to prune. Read your plant label for pruning directions or if you do not know which Clematis you have:
When does your Clematis flower?
- *flowers on old (previous year) wood in early to late spring, early summer.
*does not need regular pruning – prune to remove damaged stems or to keep your plant tidy and growing within it’s allocated space. Prune after the flowering period has ended.
- *flowers early on old (previous year) wood and again in late summer on new current year’s growth.
*prune to remove damaged or weak stems and the early flower shoots (encourages the second period of flowering) immediately after the early flowering period.
- * flowers on current year’s growth in mid to late summer.
* prune back all of the previous year’s stems to the lowest pair of live buds in early spring.
Clematis may suffer from snails, slugs, aphids or mildew. Clematis wilt is a fungal disease that may result in the sudden collapse of a previously healthy plant. Cut back affected part of the plant, even right to the ground if necessary, if fungus wilt occurs. I have to say that I have only ever experienced the odd slug-chewed clematis leaf in my garden just east of Peterborough.
Clematis will grow on a trellis and in a container, through the branches of another shrub or even up into trees. It may be used as a ground cover and the shrub types look great in the perennial border. Clematis flowers are lovely and will attract pollinators and provide them with pollen and nectar.
Read plant labels, talk to garden nursery staff and other gardeners in your area and/or google to ensure that you purchase the clematis that is right for you. We may not all become clematophiles but we can still have some of these wonderful plants in our gardens!
For more information check out:
Timber Press Pocket Guide to Clematis by Mary Toomey with Everett Leeds and Charles Chesshire, ISBN-13:978-0-88192-814-3