In my garden in Northwest England the presence of clematis in flower begins to decline towards the end of October. However, there are clematis that flower in winter and they come from the Cirrhosa Group which is mainly found in the Balearics, Corsica, and Sardinia.
They are evergreen and their natural habitat is scrubland, hedgerows, and woodland, but many have adapted to the winter garden environment of the UK. They do not do well in exposed sites but will thrive if provided with a sheltered, well drained, and sunny aspect. The stems may go brown in summer but will then reshoot and can climb up to 4 or 6 meters. Clematis from the Cirrhosa group are not vigorous and dense plants. They require no pruning but can be cut back in the spring to help them to bush out or to keep them within the space available. They should be planted at the same depth as in the pot rather than planted deeply like some summer varieties of clematis.
There are over a dozen varieties from, or linked to this group, which can be bought from garden centres, or more likely, mail order clematis nurseries. Some of the more well-known, and available varieties, are Wisley Cream, Freckles, Christmas Surprise, Lansdowne Gem, Jingle Bells, Advent Bells, Winter Parasol, Ourika Valley and napaulensis.
These varieties are so useful for winter colour and, depending on the variety and location in the garden, some will flower earlier or later than others, thus providing a succession of interest throughout the darker months.
For more information, please watch my new YouTube video on Winter Clematis