Spring may seem a long way off, but if you prune your wisteria now, you should have masses of beautiful long hanging flower racemes (clusters) in a few months’ time.
It’s the king of climbers. Its twining stems scaling house walls and pergolas, arbours and trellises, producing a riot of colour from April to June from its elegant, hanging blooms, in shades mainly in blue to violet, although you can also grow white and pink varieties.
Over here, forms of the Chinese and Japanese wisteria are the most common, thriving in sunny positions in relatively good soil and vigorously twining up to 9m (30ft).
But to keep them looking good, you need to prune them preferably twice a year.
How to prune wisteria in summer
Your wisteria needs its first prune in July or August after flowering. Cut the whippy green shoots of the current year’s growth down 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.
The summer prune will help keep this vigorous climber in check and will help stop it invading guttering and windows, while encouraging new flowering shoots rather than just foliage.
How to prune wisteria 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. At this time the plant is dormant and without leaves, new growth will start up in spring.
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. You can 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.
Remember not to let wisterias grow too tall or you will have your work cut out pruning and training them.
Which 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. It 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 with a hint of lilac in narrow tresses 25cm long.
For heavenly scent
Really fragrant varieties include Wisteria ‘Burford’, which has deep bluish-purple and lilac flower racemes around 40cm long, and Wisteria sinensis ‘Amethyst’, a vigorous type with violet-blue flowers.
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