Clematis are divided into three groups based on how and when they should be pruned.
Ideally any cutting should be done just above nodes where strong new shoots are appearing, as pictured. This should speed up new growth and encourage multiple stems, meaning the plant will bush out, leading to more coverage and more blooms.
It is worth doing this with any young Clematis regardless of their pruning code - you want the bushiness to start low down!
Pruning code 1
These are the early flowering Clematis - blooming around April and May time.
They include several species of Clematis: the evergreen cirrhosas, shaggy alpinas and macropetalas (similar in appearance to the wild Old Man's Beard), and the vigorous, small-flowered montanas.
No need to prune, but if they need tidying or untangling from their surroundings cut them after flowering time.
Pruning code 2
The large flowered cultivars - a self explanatory name!
Blooming mid-season May to July, although some flower again later in the season.
Any pruning should be carried out around about February time, just as they start to reshoot.
No need to prune unless they need tidying or untangling. Can be worth cutting back to stimulate leaves and flowers lower down the plant if it has been bare in previous years.
Pruning code 3
The late-flowering Clematis, usually out July to September.
Many have smaller blooms and are more delicate than the large-flowered cultivars.
Includes species tangutica (yellow or orange flowers), texensis and viticellas.
Cut back hard to about 1ft when new growth starts to appear - probably February-time. You might see new shoots appearing from the ground - you will be amazed how much they grow in a season!