Clematis cartmanii
These neat varieties often reach no more than 1m (3¼ft) in height. Also, unlike most varieties, they don’t cling to supports by twisting their leaf stalks, so they do need careful tying in to a trellis or frame. Alternatively, the stems can be encouraged to trail over a retaining wall.
These are superb small garden plants for winter, not the hardiest but good when thoughtfully sited in sheltered places. Beautiful in a pot in a cold greenhouse, alpine house or in a cool conservatory, they’re perhaps best displayed where the stems can trail.
The shiny, evergreen foliage is dark and prettily laced, and at flowering time is usually hidden by the mass of white flowers. ‘Joe’, with prolific, green-tinted white flowers, is the most often seen, while ‘Avalanche’ is a purer white. You may also come across the rather similar ‘Fragrant Oberon’, with greenish, super-scented flowers. These are all male plants and won’t produce seed heads. However, ‘Early Sensation’ and ‘Michiko’ are female plants and will develop masses of silvery seed heads if planted near one of the males. Pruning: Little pruning is usually needed but, if necessary, after flowering is the best time to do it.