Clematis 'Semu'

Clematis 'Semu' was introduced in 1981 by the Estonian breeder Uno Kivistik and derives from a cross of 'Jackmanii' with mixed pollen. Its 8–12 cm flowers are blue, with fine violet veining and a paler central bar. They consist of four to six pointed, slightly wavy tepals, accompanied by red-purple to brown anthers.

From July to September 'Semu' opens its flowers on the current season's growth. At around 300 cm tall, it climbs by its leaf petioles up fences, arbours, trellises and other supports. It thrives in any aspect, whether south-, north-, east- or west-facing. Plant it in moist, well-drained soil and keep the root zone cool and shaded, for instance with a layer of mulch.

'Semu' is very hardy (zone 5, down to about -29 °C). As it flowers on new growth, cut it back to about 25 cm in March (pruning group 3). Plant it so that the crown lies 5–8 cm below the soil surface, so that it shoots vigorously from below ground. The variety is occasionally also listed under the name 'Caddick's Cascade'.