CLEMATIS
A beautiful vine growing in the middle of your garden on an obelisk or growing on a trellis up the side of your garage, clematis are a beautiful and common perennial vine. The tricky part is knowing if and when to prune. Below is a guide to help you decide when and how to prune.
Pruning Group A
Clematis in pruning Group A produce flowers in early Spring on old wood, that is, stems produced last year. Plants in this group do not normally require pruning unless you want to control the size and shape of the plant. If pruning is required it should be performed after the plant has bloomed. In our climate (Pacific Northwest), this is usually between May & June. Be aware that pruning after June may reduce the number of next years blooms. Similarly, pruning too early in the Spring (before blooming) will have the same result – less flowers. You can usually recognize Group A clematis because they do not die back to the ground in winter, and generally bloom in the Spring on old growth.
Common Group A Species & Cultivars
Second hint – if a newly planted clematis – wait till the second year to start pruning.
Third hint – if there are any dead bits – broken stems or dead stems – go ahead and prune those away anytime – dead is dead and keeping any broken stems will make the plant look unsightly.
Now comes the tricky bits – if you want to put on your calendar the ‘when’ to prune your clematis – you need to know what ‘group’ of flower timing your plant fall into – especially if it is a late summer or ‘fall’ bloomer – as those types are best pruned in spring – versus the other groups that are best pruned right after they flower.
If you are unsure which time of year the plant normally blooms – it is ok to wait a year till you see for yourself.
A beautiful vine growing in the middle of your garden on an obelisk or growing on a trellis up the side of your garage, clematis are a beautiful and common perennial vine. The tricky part is knowing if and when to prune. Below is a guide to help you decide when and how to prune.
Pruning Group A
Clematis in pruning Group A produce flowers in early Spring on old wood, that is, stems produced last year. Plants in this group do not normally require pruning unless you want to control the size and shape of the plant. If pruning is required it should be performed after the plant has bloomed. In our climate (Pacific Northwest), this is usually between May & June. Be aware that pruning after June may reduce the number of next years blooms. Similarly, pruning too early in the Spring (before blooming) will have the same result – less flowers. You can usually recognize Group A clematis because they do not die back to the ground in winter, and generally bloom in the Spring on old growth.
Common Group A Species & Cultivars
- C. armandii
- C. alpine
- C. macropetala
- C. montana
- Group B
Pruning Group B contains some of the showiest and most attractive varieties including large flowered doubles and those that bloom multiple times in one year. Group B is often divided into 2 sub-groups, B1 and B2.
Group B1
Clematis in group B1 produce larger attractive flowers on old wood in May or June, followed by a second round of smaller flowers on new wood (stems that grew this year) in the Fall. Some varieties will produce double flowers during their Spring blooming period and single flowers in the Fall. In normal situations this type of Clematis will require maintenance pruning only. Pruning should be carried out in early Spring just as the plant begins to leaf. This will enable you to identify branches that did not survive the winter. Remove dead or damaged stems, trim tips, and thin out congested or tangled areas. If you prune too much, you may affect the quantity of flowers produced this year, so do not cut back any more than necessary.
Common Group B1 varieties - C. florida
- Large flowered Hybrid Cultivars including “Henryi”,”Nelly Moser”,”Niobe”,”The President”
- Group B2
Clematis in Group B2 produce flowers on both old and new wood simultaneously from June through September. Pruning should take place in late February to March. As with Group B1 or C, you should remove weak, dead or damaged stems, thin out congested or tangled areas and trim back tips. Over pruning will reduce the number of flowers produced but will not hurt the long term life of the plant. - Group C
Group C Clematis produce blooms on new wood - stems grown this year, in early Summer and sometimes through the Fall. These plants die back each year in Winter. In the Spring, the flowers of these plants begin very close to where growth finished last season. Over time flowers will start higher and higher on the plant and a bare section of stem without blooms will begin to appear at the bottom. In order to provide a great show of flowers from soil level and up, Group C clematis should be cut back each year so that only two sets of strong buds are left on each stem. This should be carried out in late February or March. While you do not need to prune group C clematis, a failure to do so will result in smaller and fewer flowers and flowers that form only near the top of the plant. An interesting alternative for these plants is their ability to be used as a ground cover.
Common Group C cultivars - C. tangutica
- C. terniflora
- C. viticella
- C. texensis
- C. integrifolia
Second hint – if a newly planted clematis – wait till the second year to start pruning.
Third hint – if there are any dead bits – broken stems or dead stems – go ahead and prune those away anytime – dead is dead and keeping any broken stems will make the plant look unsightly.
Now comes the tricky bits – if you want to put on your calendar the ‘when’ to prune your clematis – you need to know what ‘group’ of flower timing your plant fall into – especially if it is a late summer or ‘fall’ bloomer – as those types are best pruned in spring – versus the other groups that are best pruned right after they flower.
If you are unsure which time of year the plant normally blooms – it is ok to wait a year till you see for yourself.