TO KEEP climber king wisteria looking good, preferably prune them twice a year. Here's a quick guide:
1. Pruning in summer: Make the first prune in July or August, after flowering, cutting back the whippy green shoots of the current year's growth to five or six leaves. Wisterias flower on short spurs coming from the main stems, and need help to encourage flower buds to form. The mid-summer prune removes excess growth, allowing the plant to focus on producing flower buds and enabling sunlight to reach the branches, so ripening the wood. It will help keep this vigorous climber in check and help stop it invading guttering and windows, while encouraging new flowering shoots rather than just foliage.
2. Pruning in winter: Winter pruning is basically just tidying up what you did in summer, cutting back the already-pruned shoots to two or three buds in January or February, when the plant is dormant and without leaves.
3. When drastic action is needed: If your wisteria has become so overgrown that you need to hard-prune, cut back older stems to just above a strong young branch or growth shoot lower down, or even cut back an old branch to ground level. Take your time. You may need to trace and mark stems which are twining around each other, so that you don't cut off the wrong bit lower down. In the end you should be left with a framework of well-spaced branches. Don't let wisterias grow too tall or you will have your work cut out pruning and training them.
4. Good varieties to choose: For strong colour: Wisteria floribunda 'Royal Purple', a Japanese wisteria, produces stunning tresses of vivid dark lavender, pea-like flowers in racemes up to 50cm long, and also offers eye-catching autumn colour when its leaves turn to vibrant golden yellow. For subtle hues: Wisteria sinensis 'Alba', a Chinese wisteria, produces subtly scented white flowers. For heavenly scent: Fragrant varieties include Wisteria 'Burford', which has deep bluish-purple and lilac flower racemes, and Wisteria sinensis 'Amethyst', a vigorous type with violet-blue flowers.
