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Pruning a Wisteria should be carried out twice per year. Two prunings per year not only helps in the development of flowers, it also keeps the Wisteria in check; they can be incredibly invasive plants if left unpruned.

Late winter, about now is one of the times in the calendar when the pruning should be done. Pruning is then carried out again during July.

If the pruning is not carried out correctly the plant produces too much vegetative wood at the expense of flowers and you end up with too much foliage and few flowers (as demonstrated in the photograph). The vigorous young vegetative shoots need to be strongly curtailed to encourage flower production. The plant’s energy needs to be diverted into producing flowers and this is best achieved with pruning.

If you intend to prune a very neglected, twisted and totally out of control Wisteria some pruning of the very woody older stems will be required but under normal circumstances this older wood that forms the framework of an established Wisteria is left unpruned.

Use the following steps to prune your Wisteria:

1. Identify the stems that form the framework of you Wisteria. Do not cut or prune any of these.
2. It is the younger, greener more flexible shoots that need to be pruned. These are often out of control and can grow up to 4 metres in a single year.
3. If the shoot is not to be used to extend the framework of the Wisteria, cut it back to 2 or 3 buds from the main framework. This promotes the production of flower spurs.
4. Then in July, after flowering, cut back the shoots that have developed after your winter pruning to about 5 or 6 buds. This second pruning allows more light and air to be absorbed by the older woody framework, encouraging it to ripen and therefore develop more flower buds.

Wisterias do need twice as much pruning as most other climbers but your hard work will be rewarded; there is no finer site in horticulture than a well pruned Wisteria in full bloom during early summer.

Until next time, Happy Gardening.