Prune clematis that flower between late June and October now. These are in pruning group 3 and include varieties of Clematis viticella, x jackmanii and texensis, which flower on new stems made each season.
Cutting them to the base triggers fresh growth in spring and improves flowering. Not all clematis are pruned this way – just tidy up spring-flowering types in early summer and prune large-flowered hybrids at the tips in early spring.