Wisteria in Cumbrian Gardens — Beautiful, Vigorous and in Need of Regular Attention

Wisteria is a plant that causes more questions than almost any other in the gardens we visit across Grange-over-Sands, Kendal and the Cartmel Peninsula. When it is well-managed and in full bloom in late spring, a mature wisteria on a Cumbrian stone wall or house front is genuinely one of the most beautiful things a garden can offer. When it is neglected, it becomes a large, tangled mass of vegetation that does not flower reliably and can cause real damage to gutters, window frames, mortar joints and roof structures.

The good news is that managing wisteria well is not complicated, once you understand the basic principle.

The Two-Cut Approach

Wisteria needs pruning twice a year to flower reliably and to keep it within bounds. This is the single most important thing to understand about this plant. Once a year is not enough. Not pruning at all produces a vigorous climber with increasingly poor flowering that grows into every available space.

The summer pruning is done in July or August, after the main flowering period has finished. This involves cutting back all the long whippy new shoots that have grown since flowering to approximately five or six leaves from the main framework of branches. The point of the summer cut is not primarily about size control but about encouraging the plant to develop the short flowering spurs that produce next year's flowers. Those long shoots, if left, would grow on to become more framework branches rather than producing flowers.

The winter pruning is done in January or February, when the plant is dormant and you can see the framework clearly without leaves in the way. This involves cutting back the same shoots that were reduced in summer to two or three buds from the main framework. This shortens them further and encourages the development of the flower buds that will open the following May or June.

The buds for next year's flowers are present and visible in winter as plump, round, slightly furry-looking buds on the short spurs close to the main branches. These are what you are trying to encourage and protect with the pruning programme. Long, whippy vegetative shoots have pointed buds and should be reduced. Round, plump flower buds should be left as intact as possible.

Wisteria and Buildings

Wisteria is a vigorous, woody-stemmed climber that, if left to its own devices, will find its way into any gap in masonry, timber, gutters or roofing. In the older stone-built properties common in Grange-over-Sands and the Cartmel Peninsula, the mortar joints of stone walls can be widened by wisteria stems growing into them over many years. Gutters filled with wisteria growth overflow rather than drain. Window frames and door frames can be deformed by wisteria stems growing into the gaps around them.

None of this means wisteria should not be grown on buildings. It simply means that the annual pruning described above is not optional for a wisteria on a house wall. Without it, the plant will cause structural problems within a relatively few years. With it, a wisteria can be maintained as a manageable, beautiful and largely harmless feature for many decades.

Getting a Neglected Wisteria Back Under Control

If you have a wisteria that has not been pruned properly for several years and has grown beyond the area where you want it, recovery is possible but requires patience. Do not attempt to cut it back drastically all in one go. Instead, start the twice-yearly pruning programme and also remove one or two of the oldest, most congested stems each winter until you have reduced the plant to a manageable framework. Hard pruning all at once tends to produce an explosion of vigorous vegetative growth and very few flowers for one or two seasons.

The plant will begin to flower more reliably within one to two seasons of the pruning programme being properly established, even if it has been neglected for some years before.

Is Wisteria Suitable for Cumbrian Gardens?

Wisteria is not reliably hardy in very exposed or cold positions in Cumbria, and it performs best in a sheltered, south or south-west facing position with protection from late frosts, which can damage the early flower buds. In the milder, more sheltered gardens of Grange-over-Sands, Cartmel and the Windermere area, wisteria does very well. In more exposed positions, the display may be less reliable year to year.

The most commonly grown species are Japanese wisteria (Wisteria floribunda) and Chinese wisteria (Wisteria sinensis), both of which perform well in Cumbrian garden conditions where shelter is available. There are also cultivars with white and pink flowers as well as the more familiar purple-blue, and some with much longer flower racemes than others.

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