How do I prune my Wisteria?

I don’t want to wait 10 years!

How can I make it flower?

Right up there with Clematis pruning questions, we’re asked pretty much weekly what customers can do to help their beautiful Wisteria flower. So we’re going to try and show you how this is done.

Are you paying attention?

Well before we dispel a couple of myths, you need to start with one factor which without, quite simply your Wisteria will never…..ever….ever flower its little socks off…..

It all starts here…

No sunshine = no flowers

It’s as simple as that. Wisteria need sunshine to flower, plain and simple. The more sunshine it gets, the more flowers you’ll be rewarded with. Don’t get me wrong, Wisterias will grow beautifully in shade, they’ll be verdant, vigorous, but very much lacking in flowers!

Why? Well, so many plants which produce flowers on older wood, need their wood to be ripened in the sunshine to inititate a good set of flowers. That’s not to say they won’t grow well with very little sunshine…they will! But we grow Wisteria for its flowers. Sunshine is kind of compulsory.

Years ago I listened to BBC’s Chris Beardshaw who told the audience that if a plant doesn’t earn its keep in your garden, get rid of it! And I wholeheartedly agree with him. There really is no point giving house room to a plant that just doesn’t perform for you.

So…..sunshine is vital. Agreed?

Now most flowering plants only need pruning once a year to give you their best show; Wisterias need it twice, and I’m sure that’s why people get a little apprehensive about pruning them.

I promise you it’s easy. I also promise you that if you do it a little bit wrong, you won’t hurt your prize Wisteria…..unless you raze it to the ground, it will recover quickly from ‘over-ambitious’ pruning!

So, let’s begin. Wisteria is a climber and although it can be grown as a wall plant, a pergola plant, it can be grown as an arch, against railings, or even as a tree…..the technique to encourage flowers is always identical.

Being so vigorous, Wisterias have a real habit of becoming overgrown all too quickly…..and if that happens, it gets harder to see the wood for the trees (sorry).

So if you prune it each year to prevent this, you’ll save yourself a lot of work. Let’s assume you have a Wisteria that’s fairly mature, and it’s Summertime. Round 1….

By August or September, your Wisteria could be looking something like this….

All a Wisteria wants to do is grow, grow and grow. It’s an Asian climber and it’s spent millions of years evolving to climb trees with its prehensile shoots. Unhindered, it could easily reach 30 or 40 feet into the canopies of trees.

Your mission…..if you choose to accept it…..is to use your secateurs to curb its enthusiasm!

OK, so take a look at your Wisteria and you’ll very soon notice that it’s produced masses of green extension growth on whippy stems, sometimes these could be 10 feet long or more. The most important thing to identify is where the growth started from. It began growing from one of last years stems, and above all else, this is the bit that’s most important. Trace that long whippy shoot back to the main stem, and identify where it began. It would look something like this….

That’s it!

A green shoot coming from a brown stem

Just to the left of the secateurs, that long green shoot has sprouted from one of last years shoots, which is now woody and brown. If you can learn to identify this point of growth, suddenly Wisteria pruning is a piece of cake!

So, basically, get this……you cut back EVERY SINGLE ONE of these long, green whippy shoots back hard. In August or September. As a rule of thumb, count about 6 leaves from where the green shoot comes out of the brown one, then snip everything else off. Easy, right?

Your Wisteria will lose nearly all of its growth that it’s worked so hard to produce this year. And I promise you, that’s a very very good thing.

So you see what we’re trying to achieve? To the right of the secateurs (at approximately 2 o’clock) can you see where last years stem finishes, and this years stem begins? It looks like a little brown circle. It really doesn’t matter if there are six leaf joints left, or a few more. This is just Round 1.

Are you ready for Round 2?

Now wait until Winter

and wrap up warm!

So you’ve done all the hard work back in Summer. Winter pruning is still important, but it’s a lot easier as your Wisteria will be bare…..so you can see everything clearly.

So those long whippy shoots, which you reduced to around six leaf joints, will by now have changed colour from bright green to a greyish colour. And it’s time to trim them by half. I’d do this in January or February.

The chap above is just about to trim one of the Summer trimmed shoots back to half of it’s buds (those black things clinging closely to the stem). He’s identified three good buds on a tiny bit of this years stem, and he’s going to take the rest off, leaving something like this….

10 feet of growth….

Snipped to just 3 or 4 buds….

Can you see then, that all of that lush, vigorous growth has been curtailed and restricted to just three or four buds?

Why do we do this? Well, that’s easy, Because in a year or so, you’ll see these thin black buds turn into big fat buds, and when you see those big fat buds you’ll know you’ve achieved success…..because they’re going to be your flowers!

Mission accomplished

You are now officially an expert!

Don’t forget that Wisteria does it’s thing on older wood. It takes a year or two for those thin black buds to develop internally, to become fat flower buds. But if you adopt this technique every year, and you’re growing your Wisteria in full sun, I promise you will achieve success!

So what about this ‘takes ten years to flower’ myth? Well, it is. And it isn’t. These days, Wisterias are generally produced commercially using something called a nurse graft. Grafting is used on lots of plants (apple trees and roses for example), where it’s necessary to use a different root to encourage a favoured attribute….in this case, flowering.

So, if you buy a Wisteria from a nursery or Garden Centre, it’s always wise to find out first if it’s a grafted one (they aren’t always…but ours are!)

If you try and grow a Wisteria from seed (which of course happens naturally in the wild), there’s every chance it may take 10 or 20 years to flower. Equally likely, it may never flower!

You could, of course, take cuttings from an established plant, but without the correct root to help it, again it may not flower like its parent. It’s one of those plants we’d wholeheartedly recommend you buy from a reputable source, buy it grafted, and be prepared to pay good money for it. There’s really no point scrimping on a cheap plant if it’s not going to flower, right?

As a rule of thumb, even when it’s grafted, all Wisterias don’t all flower at the same time. In our experience, the whites and the very pale mauves always seems to reach flowering maturity first (often flowering here at the nursery), the traditional blues and mauves tend to take a year or so longer, and the really deep purples tend to be the last to start (varieties like ‘Black Dragon’). So again, depending on your choice, don’t be surprised if even a grafted plant doesn’t flower immediately. It’s quite normal! And it is just a rule of thumb….Mother Nature is firmly in charge and often proves me wrong!

Do hope this helps…..don’t forget we’re always very happy to help here at the nursery, if you’re not quite sure where to start.

Happy snipping!