5 Simple Steps to Winter Prune Wisteria for Maximum Flowers Come May

Dreaming of a waterfall of pretty wisteria blooms cascading over your pergola come May? Winter is the time to take these five easy steps that will turn your dream into reality. Wisteria is a vigorous plant, and a pre-growing-season prune will ensure it puts all its energy into forming glorious flowers rather than lots of long, leafy stems. It'll also help control the size and shape, and keep the plant healthy.

When's the Right Moment to Prune?

In winter, wisteria is not only dormant but leafless, so you can easily see its structure, which makes it simple to work out which stems to snip off. The right time to prune is just before the plant’s buds begin to swell – and certainly before they open – in January or February, depending on your USDA zone.

What Shape Do You Want?

You can train wisteria into any shape you want with regular pruning. A handy tip is to think of your wisteria as a tree with a trunk, some main branches and lots of twiggy stems. It doesn't need to be a tangled mess – although this vine will happily grow into one if you leave it to its own devices! Be confident, and create a strong framework in whatever shape you'd like, to show off its fabulous flowers.

You may want your 'tree' to have one main trunk. If you're training your plant up and over a pergola, this 'trunk' might be quite tall; if the wisteria is on a house wall, it may be much shorter. Or would you prefer your wisteria to be more like a multi-stem tree, with numerous 'trunks', perhaps trained into a fan or espalier shape?

While your plant is young, you'll want to build the framework of this ‘tree’, choosing which of last year’s growth you want to keep to add to its main structural frame. Leave this unpruned, or shorten it only to the length you need. With the rest of the plant, however, and if your wisteria is more established, it's time to be brutal to keep this fast-growing beast under control.

How to Winter-Prune a Wisteria

1. Deal With Last Year’s Growth

Your first step is to cut back all of last year’s growth to two or three buds above the older, woodier main stems. This not only gets rid of any excess length, but the short spurs will yield more flowers. Clearing this recent growth also means the blooms won’t be hidden behind a forest of foliage.

As you prune, keep the overall skeleton of the wisteria in mind. New growth will typically be in the direction the last bud faces, so by choosing which bud to cut above, you can avoid congestion, fill any gaps or encourage your plant into a wider shape or shift to the left or right.

Make sure you cut just above a bud – around 3mm is good – rather than leaving a stub of stem above it. This stem-end will die and could carry disease into the plant. Make angled cuts, as this will help prevent water settling on the stem ends.

2. Remove Damaged Sections

You’ll likely come across a few dead or diseased stems, or sections that have been damaged by winter storms. Snip these right back to the main branches or trunk, making a cut that’s flush with the older stem.

If you’re not sure if a stem is dead or not, lightly scratch its surface with one of the pruner blades: if you see any green, it’s still alive.

3. Take Out Unwanted Stems

Now take a step back and look at the whole plant. Are there any unwanted stems? You might need to thin a congested area, remove a stem that’s crossing another and is likely to rub and cause damage, or remove some outer growth if you want to keep your wisteria compact. Aim to create an airy framework.

It’s fine to shorten older stems as long as you cut just above a younger shoot. If you want to take out a whole stem, cut it off flush with the branch or trunk, or at ground level. Don’t overdo it, though. If the plant hasn’t been pruned in a few years, or you want to remove thick, woody stems, it’s best to gradually reshape your wisteria over a few years.

4. Tidy the Base

Look for any suckers coming out of the ground around the wisteria’s base, and cut these off at ground level. Many wisteria are grown on grafted rootstock, so these stems could be a different plant altogether!

It’s a good idea to remove any branching stems from the first foot or two of the main trunk, or trunks, as these are unlikely to be flowering stems.

5. Check Ties

Before you finish, check existing ties are still strong, and tie in any unattached stems to the support. Velcro ties like these One-Wrap Garden Ties from Amazon are a great choice for wisteria as they're easily adjusted as stems thicken.

What Tools Do I Need?

A quality pair of hand pruners, such as these Fiskars Bypass Pruning Shears from Amazon, is a must. It’s vital that they’re sharp, as clean cuts are far less prone to disease. If you’re in any doubt, a tool such as this Coroner Blade Sharpener from Amazon is a wise buy to give your pruners some TLC.

If your wisteria is a fairly young plant, or has been regularly pruned, then you’re all set. However, if you’re tackling a wisteria that hasn’t been pruned in a few years, or you want to reshape the plant, you’ll need to bring in the heavy crew. Old wisteria stems are woody and can be tough to cut, so a pair of assisted action pruners like these Ratchet Pruning Shears from Amazon will boost your cutting power. For really thick stems, and for getting into awkward spots if stems are tangled, a pruning hand saw such as this Fiskars Hand Saw from Amazon is a better choice.

If your wisteria is trained above head height, then these Long Reach Cut & Hold Pruners from Amazon will cut stems up to half an inch wide, or reach for a sturdy step ladder such as this Foldable 4 Step Ladder with Handrail from Amazon.

A tarp with handles like this Heavy Duty Tarp from Amazon makes clear-up quick.

When Should I Prune Again?

It’s best to prune your wisteria twice a year, every year. Every January or February, carry out this shaping prune. Then in August, it’s a smart move to do a second, less severe, prune. All you need do in late summer is cut all the long, whippy new growth back to five or six buds. This keeps the plant tidy over winter, and makes your primary winter prune much easier.