Designing Beautiful Borders

How to prune a clematis.

Now is the time to prune clematis which fall into pruning groups 2 and 3. If you have no idea what I am talking about, then do read on!

Clematis produce some of the most stunning flowers of any climber, but they are also one of those plants that people seem to commonly fail with. One area that causes particular confusion is pruning. To prune a clematis successfully, you need to know which of the three pruning groups (1,2 or 3) that your clematis falls into.

How do I know what pruning group my clematis falls under?

If you have binned the original plant label, or can’t remember the name of your clematis to google it, then you can work out your clematis pruning group by noting the time of year that it flowers;

Group 1 clematis flower early in the year, on shoots grown the previous season. This includes the winter flowering clematis like cirrhosa, through to those that flower mid-spring like the montana below.



Group 2 clematis flower around the May/June period and are distinctive due to their very large flowers. They often will repeat flower, later in the season. Group 2 clematis flower on short shoots grown on growth from the previous year and sometimes a second flush of flowers is also produced on new growth from the current season.


Group 3 clematis flower from mid to late summer on the current seasons growth



How and when to prune

Group 1 clematis need no regular pruning and can be left to romp away. However, if the clematis has romped beyond its allotted space, or it is looking tangled and messy, you can cut these clematis back hard, (to the base if necessary). This should be done as soon as possible after the clematis has flowered, as it requires time to make new growth for next year’s flowers. The exception to this rule is the evergreen C. armandii which needs lightly pruning back to its allotted space.

Group 2 clematis are where things can get confusing. I think this is because advice can change depending on who's giving it. It’s fair to say that more than one approach will work. Here are two different ways of pruning a group 2.

Option 1.

-         In late winter/early spring, (now) remove all dead or weak stems, cutting just above a healthy bud. The aim is to tidy up the clematis. Try and vary the length of the stems, so that the flowers are spaced out more favourably.

-         After the first flush of flowers, cut the stems back by half, (around July time)

Option 2.

-         Leave the clematis unpruned, then every 3-4 years, cut back hard in late winter, to about 30-90cm from the base. You will lose the first flush of flowers for year 1, but it does provide a straight forward way of pruning.

Group 3 clematis are nice and straightforward. In late winter, cut all stems down to 15-30cm from the base, cutting just above a healthy bud. If you don’t cut these clematis back, they will continue to grow from where they left off the year before. This results in the flowers being well above eye level and the base becoming very bare, which is not so attractive!