Clematis 'Avalanche'

Clematis x cartmanii 'Avalanche' was bred in 1990 by British nurseryman Robin White at Blackthorn Nursery from a cross between Clematis marmoraria and Clematis paniculata, and registered under this name in 1996; in the trade it sometimes appears under the synonym 'Blaaval'. The pure white, male flowers with striking yellow stamens appear in dense clusters and, at 5 to 7 cm across, rank among the largest in this evergreen group.

'Avalanche' flowers just once, but abundantly, from March to April on the previous year's wood - there is no repeat bloom, and true to its name it appears like an avalanche of white flowers. Growing 120 to 150 cm tall, it suits containers, low trellises, wall tops or as a trailing plant over banks; the site should be sunny to partly shaded, sheltered and well drained.

The variety is only moderately hardy (zone 8, down to about -12 °C) and benefits from winter protection or container culture in exposed locations. For a compact habit, cutting back to about 75 cm in May is recommended; however, as an early-flowering group, no regular pruning is required - a light tidy-up right after flowering is enough.