Which Month Should I Prune Wisteria UK?

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Wisteria should be pruned in January in order to remove long unruly stems. Remaining stems can then be tied onto strong supports. Wisteria can also be pruned in August to improve flower production and to remove long green whips that may be finding their way under roof tiles and windows.

Fortunately, pruning wisteria isn’t complicated and the plants are pretty forgiving if you make a mistake. Follow a few simple rules and your wisteria will reward you with many beautiful blooms year after year.

Is it too late to Prune in March?

Wisteria should be pruned in January while the plant is dormant. However, if you haven’t managed to get into the garden in the depths of winter, It is acceptable to prune your wisteria in very early spring. Try to avoid the warmer spring weather when pruning very soft green growth. Green growth can suffer from dieback, which could travel down the stem and damage sections of the plant.

Can I prune Wisteria in the Summer?

Wisteria should also be pruned in August. This is an important time to prune wisteria because removing long leafy stems allows sunlight to ripen the wood of flowering spurs. Wisteria can put on excessive growth which, not only winds its way around other stems, making it difficult to prune in January but also finds its way under roof tiles and into gaps around windowsills.

How to Prune Wisteria to Improve Flowering

Keeping wisteria under control will not only create a nice tidy framework but will also encourage flowering. Allowing the plant to grow excessively large, will reduce the chances of an abundance of flowers.

  • When pruning wisteria in August
    • Cut back leafy stems to 5 or 6 leaves away from the main stem. Make the cut 5mm above the bud.
  • When pruning wisteria in January
    • Cut back the stems you pruned in August, back further to 2 or 3 buds from any older wood.

As with most plants, wisteria responds to nitrogen by putting on an excess of leafy growth. This may be one reason why your wisteria might not be flowering well. Especially if the wisteria roots are receiving nitrogen from a nearby lawn that may have been recently fertilised.

Feed wisteria plants in the spring with a rose or flowering shrub fertiliser. You can even feed the plants with a tomato fertiliser because it contains the vital phosphorous, and potassium required for flower production.

Gardeners Tip: Wisteria stems can get hard and woody. Consider buying cordless secateurs to help with pruning. Tying in strong woody stems can also be a chore, there are some great auto tying machines which can help with attaching strong stems to their supports.

When Can I Hard Prune Wisteria?

Hard prune or renovate wisteria in January. Plants can get out of hand and stems may have grown across doors or windows. Wisteria will respond well to a hard prune or renovation. However, bear in mind that, wisteria stems can grow very long and it might be a good idea to trace the stem from start to finish, to make sure you are not removing any stems that might leave an unwanted or unsightly gap!

If drastic measures are needed, wisteria can be cut back to near the ground. BUT! beware, this kind of heavy pruning will encourage plenty of leafy growth. Keep an eye on the plant and refrain from feeding. Remove any unwanted stems in August to keep the plant in check this will also ensure the plant puts energy into flowering and not leafy growth.