Wisteria Pruning

The process of pruning wisteria

Wisterias, while they can be left to grow and ramble unchecked where space permits, will typically flower more abundantly and regularly if they are pruned twice a year. The act of removing growth during the summer months allows for improved air circulation and enables more sunlight to reach the base of the young growths. This encourages better ripening of the wood and enhances the likelihood of flower bud formation. By limiting the amount of vegetative growth and promoting short, flowering spurs, you can expect a greater number of flowers. 

The method for summer pruning of wisteria

After the wisteria has flowered, which usually occurs in July or August, it’s recommended to cut back the whippy green shoots of the current year’s growth to five or six leaves. This practice helps control the size of the wisteria, preventing it from encroaching into guttering and windows, and encourages the plant to form flower buds rather than focusing on green growth.

The technique for winter pruning of wisteria

In January or February, when the plant is dormant and leafless, it’s advisable to cut back the shoots you pruned in the summer to two or three buds. This helps tidy up the plant before the growing season commences. It also ensures that the flowers won’t be obscured by leaves when they bloom.

The approach to hard pruning or renovating wisteria

With older plants, severe pruning may be necessary to remove old, worn-out growths, or branches that are growing over windows or protruding outwards from the face of the building. Similarly, hard pruning may be required where maintenance needs to be carried out on the structure supporting the plant.

This may involve drastically shortening back long branches, removing sections of older stems to just above a strong young branch or growth shoot lower down, or cutting completely back to a main branch, or even to ground level. A careful, unhurried approach is needed if larger, thicker branches are to be removed and where a branch is twining it may be necessary to trace back and mark it at intervals with string before removing it. The end result should be a skeleton framework of reasonably well-spaced branches.

Additional points to consider when hard pruning;

Hard pruning will stimulate strong, new growth so it is advisable to avoid feeding in the first spring after hard pruning. If there are gaps in the framework, suitably positioned new growths can be trained in to form replacement branches, with flowering usually resuming in two or three years’ time. Often there is strong basal shoot growth. If these shoots are unwanted for replacement branches, they can be removed. Any such pruning can be done during the period from leaf fall to early February. Other new growths can be pruned back in the summer and winter as per the normal routine pruning.