Can you please give me some advice about clematis pruning? I have looked it up a couple of books but it still seems to be a complicated subject.

V Moss, Worcester.

If I were to attempt to sum up clematis pruning in one sentence it would be as follows: The earlier your clematis flowers the less you need to prune it back, the later your clematis flowers the more you need to cut off it.

The cut off point for flowering early or late is July. If your plant normally carries a flush of blooms before July then, according to my summary, it is early flowering.

Remember that not all clematis necessarily need to be pruned every year, as long as they have not yet filled their allotted space then many of the early flowering ones can be left unpruned. Where pruning is necessary here is how I would tackle the job.

First, the earlier flowering ones such as C. alpina, C. macropetala and C. montana along with the evergreens C. chirrosa and the fabled C. armandii all of which are pruned, if it is required, just after they finish flowering. This is mainly a case of removing any dead stems and reducing over-vigorous shoots by up to two thirds. Next, we come to the large flowered early to mid- summer blooming hybrids that can produce two lots of flowers a year, the large ones in May/June followed by a further flush of smaller blooms from August onwards.

This group includes favourites such as Nelly Mozer, Barbara Jackman and double flowered varieties such as Dutchess of Edinburgh and Vyvyan Pennell.

Clematis in this group just need a tidy up after the first flush of flowers fade, which stimulates the production of new growth that will flower later in the summer.

It is worth remembering that the late blooms of most double flowering varieties are only single.

Now we arrive at the only section that definitely require pruning every year, the ones that bloom only from July onwards into the autumn, such as the jackmanii group and the viticella varieties, along with species such as C. orientalis and C. tanguitica. These must be pruned hard back, to as low as 30cm (1ft) above the soil if possible, just as growth begins in February. If this pruning regime is not carried out then all you will have at eye level will be bare stems, as all the flowers are carried on young growth, which will all be at the top of the plant.