Prune Wisteria in July or Risk Losing Next Year's Flowers

Do you dream of cascades of enormous wisteria flowers but get a vine-full of foliage instead? This plant blooms on the previous year’s growth so the secret to get bigger wisteria flowers next summer lies in what you do with it now. Prune wisteria in July and you'll direct all its energy into growing next year's flowerbuds.

In July, your wisteria vine has finished producing this year’s flowers and gets busy growing long, whippy stems full of leaves. Leave these straggly stems to flourish and you won’t just have a giant plant on your hands, but far fewer flowers next year, and perhaps none at all.

Remove those unruly long stems now, however, and you’ll force your vine to focus its energy on growing fat flowerbuds for a waterfall of big, beautiful blooms next May and June. And it's easy to do, even if you're a beginner gardener. Pruning a wisteria vine is a key July gardening job, and a summer trim also makes its second prune at the end of winter so much quicker to do. Ready? Here's exactly how to prune wisteria in summer.

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How to Prune Wisteria in July

First, trace the new, straggly stems – called whips – back to the point they emerge from the main framework of the vine. Then count five buds or leaf stalks along the whip and use bypass hand pruners such as these from Amazon or a pair of pruning scissors like these from Amazon to cut just above that fifth bud.

Shorten all the whips in this way. If you find some have already wound themselves into a big tangle, don’t worry about untangling them – just get snipping. It’s not critical to precisely count five buds or leaf stalks, that’s an optimum number to aim for.

If your vine also has bare stems hanging downwards, snip those off too. These are what’s left of this year’s flowers and they’ll soon turn yellow and look unsightly. If there are seedpods attached, you might want to leave them to enjoy the sight of these silvery adornments. But, if your goal is huge flowers next year, it’s best to remove them as that will prevent the vine from wasting energy on seed production.

Removing all this whippy growth halts the wisteria’s rampant growth and stops the plant putting all its energy into growing stems and leaves. And that's important: wisteria certainly isn't one of those well-behaved vines that won't scramble out of control. This vine has evolved to grow rapidly up through tall trees in a forest to reach the sunlight, so growing all these whips to help it clamber up through a tree canopy to get life-giving sunshine is its number one priority in summer.

So, removing the whips saves a whole heap of energy that can be used to grow bigger flowers.

Getting rid of this leafy growth also allows more sunlight to reach the short lengths of woody stems left, which is critical. Sunshine is necessary to ripen this wood, and more sun will grow fatter flowerbuds for bigger blooms. Skip pruning your wisteria in July and all the foliage that grows on the whips can block so much sunlight that your vine doesn’t flower at all the following year, as flowerbuds only form on sun-ripened wood.

The other advantage to pruning wisteria in July is that it keeps this vigorous vine, which has the potential to become invasive, under control. Leave these whips in place and each one is capable of growing up to 10 feet long. Once they've hardened into a woody tangle around drainpipes and chimneys, pruning them in late winter is a far harder task.

So now you know exactly what to do, you can be confident about trimming your vine to get more wisteria flowers, avoiding common pruning mistakes. By shortening the whippy growth in July, your vine will produce less foliage and more flowers for a spectacular display next year.

How to Prune Wisteria in Late Winter

Wisteria needs pruning twice a year, once in late summer and once in late winter. And the good news is that shortening all the whips on your wisteria in July makes the main winter prune so much easier.

When winter-pruning a wisteria vine in January or February, you simply need to reduce those stems you cut in July further, to two or three buds. You can tell which are the flower buds and which are the leaf buds: the fat, teardrop-shaped buds will form flowers, while the thinner, flatter, more pointed buds will grow leaves. Creating these short spurs concentrates all the plant’s energy into the fattest buds at the base of the stems, giving you much larger flowers.

In late winter, you can also prune to remove dead, damaged or diseased stems, to keep your vine healthy, but leave the main framework alone.

Other Plants to Prune in July

If you’ve only got time to prune one plant in July, make wisteria your priority. Here’s what else can be pruned in July, once you’ve done that vital task:

• Early-flowering shrubs such as philadelphus (mock orange), weigela, forsythia and deutzia, if you haven't pruned these already. All these shrubs flower on the previous year’s growth so pruning them now gives them plenty of time to form fresh growth and next year’s flowerbuds.
• Fast-growing hedging plants such as privet. While you should trim slower-growing hedging plants such as box, hornbeam and beech at the beginning of summer, and again at the end, giving faster-growing plants such as privet a trim every 4-6 weeks will keep it in shape.
• Early-flowering honeysuckle, once it’s finished flowering. Reduce flowered shoots by a third and, if your plant is only flowering at its stem ends, cut up a quarter of stems to two feet from the ground to encourage blooms across the whole plant.
• Fruit canes that have finished fruiting, such as early-fruiting raspberries. Cutting old stems off at the base to make room for new stems.
• Rambling roses that aren’t rebloomers, if they’ve finished flowering. The ideal time to prune ramblers is immediately after they’ve finished flowering in late summer, shortening the side branches to around 4 inches and clearing out any old wood.
• Trained fruit trees such as cordon apples and pears. Standalone fruit trees are pruned in winter but shoots on highly trained trees can be shortened now.