Overgrown Wisteria

danhaubert.dh

Okay folks I need some advice please.  This problem wasn't created by me but its my problem now.  I moved into a new house only to find this overgrown and neglected wisteria.  And underneath is a really cool pagoda in need of repair.  It is literally bring pushed off its foundation by the weight of the vine.  I would like to save this poor vine if possible.  It is the beginning of December here in central Pennsylvania USA.  I would like some detailed instructions on how and when to prune this wisteria since I've never dealt with one before.  Especially one in this condition.  Please see the attached photos.  Help...

Dave Humby

There’s lots of good instructional videos on YouTube and the RHS website has detailed instructions. 

Winter is a good time to do the ‘second’ prune to take growth down to two or three buds on your chosen limbs. This promotes flowering rather than just leaf growth.

You can be quite aggressive. Remove the spindly growth so that you have more structure. You can also train new growth as desired. 

Lizzie27

What are your winters like? As Dave says, winter is a good time to prune wisteria but if your winters are really harsh, it might be better to wait until early spring but before the wisteria starts budding. I would drastically cut down most of that top growth, until you can see the structure underneath, keeping some of the biggest and longest branches, then tying them securely with soft tie that stretches a bit so you don't strangle the stems. After that water it well (depending on your weather conditions). I hesitate to recommend feeding the wisteria as they don't usually need it, but the cutting back will give it rather a shock so it could be okay. When next July arrives (if the wisteria has survived and is growing again, you can prune back the new long whips as their stumps should flower the following year.  Hope this helps.

Obelixx

You need to start by cutting back every stem that is hanging down between those columns so you can see and walk through without obstruction.   Then do a similar hard prune on the outside of the structure so you can see the columns.  Then you should be able to see if any of the main stems need cutting back or thinning out.

By then you should also be able to judge whether the structure needs major repairs or just a tweak here and there to reinforce it.    Best to get that done before growth starts in spring.

You may not get flowers this coming spring after such a hard prune but you will have a framework to work on.  new stems will be produced and they will be long and whippy.  These need pruning back in July to shorten them and then they get another cut in late January to promots flower bud formation for the spring display. 

If your summers are very warm you'll need to cut back new stems all thru July, August and September to keep the long whippy stems controlled.  I do in this garden but they still carry on flowering sporadically till late September.

The RHS offers this advice on pruning wisteria - https://www.rhs.org.uk/advice/profile?pid=242 and a video - https://www.rhs.org.uk/videos/advice/pruning-wisteria