Pruning wisteria: when and how, by type

Wisteria is pruned twice a year. In July you cut back this year's long shoots to about six buds, around 12 to 15 cm. In January, when the plant is bare, you cut the same side shoots back further to two or three buds (5 to 8 cm), just above a fat, round flower bud. Leave the thick main branches: they form the framework from which the flower clusters hang.

Pruning wisteria by situation: the table

Chinese, Japanese and other species

Chinese wisteria (Wisteria sinensis) grows most vigorously and flowers early, often before the foliage is fully out. You can cut it back hard in July. Japanese wisteria (Wisteria floribunda) grows a little more calmly and has longer clusters; with a cultivar like 'Multijuga' you cut back to three buds rather than two in winter. Wisteria brachybotrys is a moderate grower that manages with light summer pruning. The method is the same for all species: two pruning sessions, only the depth differs.

Young wisteria: first a framework

A newly planted wisteria is not pruned in the first year. You tie the long shoots gently along wire, trellis or a pergola, preferably horizontally or at an angle: this gives more flowers later. From the second year you choose the two or three strongest shoots as main branches in March and cut back the rest to three to four buds. In July of that year the first real summer pruning follows. A young wisteria needs some patience before it flowers well.

Mature: summer pruning in July

In July the plant has produced long, thin shoots. You cut these back to about six buds from where they emerge from the branch. It's about the number of buds, not the length. Leave enough foliage so the plant stays healthy, and remove shoots that grow into the gutter, over windows or around pipes. Preparation can start in May: in preparing wisteria in May you can read how to recognise the long shoots. A second description of the same pruning with tips on feeding is in wisteria summer pruning in July.

Mature: winter pruning in January

In winter the plant is bare and you can see the buds clearly. Flower buds are round and fat and often sit in clusters; growth buds are small and pointed. You cut back the side shoots that you already shortened in July to two or three buds, always just above a flower bud. Dead wood, tangled branches and shoots that grow too far beyond the support also come out. Then tie the remaining branches loosely and securely again.

Over a pergola

On a pergola the main shoots grow up the posts and over the beams. You don't prune these main shoots in July or January: they form the framework. The side shoots that hang down from the beams get the same two pruning sessions and carry the clusters. If you want more light through the pergola, cut these side shoots a little shorter in July.

If the wisteria doesn't flower

A wisteria that has only produced foliage for years is usually not pruned or pruned too cautiously. Start with summer pruning in July and do the winter pruning in January; flowers often follow after one or two years. Too little sun (less than six hours a day) and too much nitrogen also inhibit flowering. A plant from seed can take a very long time or never flower properly.

If you're unsure where a wisteria looks best, against the wall or over a pergola, with a garden design you can see on a photo of your own garden how it fits with the rest of the planting.

Step-by-step plan

Step 1: Prune the long shoots in July

Find the long, thin shoots that have grown this year. Leave the thick main branches alone.

Step 2: Cut to about six buds

Cut each long side shoot back to about six buds, around 12 to 15 cm from the base of that shoot. Leave enough foliage.

Step 3: Remove shoots that are in the way

Cut shoots in the gutter, over windows or around pipes completely away.

Step 4: Recognise the flower buds in winter

In January, when the plant is bare, look for the fat, round flower buds. The pointed buds are growth buds.

Step 5: Cut to two or three buds

Cut the same side shoots back to two or three buds (5 to 8 cm), always just above a flower bud.

Step 6: Tidy up and tie again

Remove dead wood and tangled branches, and tie the remaining branches loosely with soft twine or ties. Clear away the prunings: wisteria seed pods are poisonous.