Answer: Deciduous shrubs such as your Viburnum may be pruned at two different times of the year (late winter or early spring, and after flowering) according to the characteristics of the plants. Remove dead wood clear to ground level. Diseased and broken parts of shrubs should be removed, however, when you first noticed them regardless of time of year.
Wisterias can be left unpruned where space allows, but flower more freely if pruned in summer and winter to build up a spur system.
In August, shorten-back current season?s shoots to 12inches. This allows more sun to get to the wood, encouraging flower-bud formation.
In February, shorten-back the summer-pruned shoots to within 1-2 inches of older wood, or to two to three buds. It should be possible to distinguish the plumper flower buds from the slimmer growth buds.
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