Why won't my wisteria rebloom?

inespilarApril 26, 2012

I bought my house 11 years ago. That first spring the wisteria bloomed beautifully. It's pretty big, growing over a split rail fence. I would imagine it was at least 15 years old if not older. The next two years it became wild and started taking over the garden. I pruned it very hard and it has never bloomed well since then. During this time, it has sent runners throughout the garden, up trees etc which I have cut down, but sometimes not until Sept or so. I realize I may not have pruned properly (just watched some videos on youtube) but I cut back enough of the new growth that I would think it would have helped the plant. It seems when you search everyone is complaining that their plant never bloomed. This one bloomed two springs for me and probably many springs before then. Please help! Thanks!

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woodyoak zone 5 Canada(5b)

How low did you prune it down to when you first cut it back hard? Most wisterias are grafted plants - is it possible that you cut it down below the graft union? If so, the new growth may all be from the root stock. The root stock is often from seedlings - and may be Japanese wisteria while the blooming part may have been Chinese wisteria. If you are dealing with the root stock, it can take many (14 or more) years to bloom - if it ever does - and it could/most likely will be an inferior plant. The bits that were going wild were probably root suckers - they always need removing, preferably by digging down and ripping them off the roots to remove the bud-wood. It's hard to get rid of a wisteria so it's hard to say what is best to do at this point. You could select one or two thicker - older - stems to keep and train as a tree and diligently remove everything else and hope that you eventually get it to reflower. Or you could try to remove it all - is it somewhere where you can at least mow over it to help conrol new growth and eventally exhaust the roots to kill it? (plus use some heavy-duty chemicals on it!)

    Bookmark   April 27, 2012 at 4:49PM
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inespilar

Where would the graft union be? Near the soil line? The plant is nearly 6 feet tall and I have only cut the growth that extends horizontally and is newish. Interesting about the root suckers. Thing is sometimes they bloom, and more than the plant. Very perplexing. I guess my goal for this season is to massacre all the root suckers and learn how to prune the plant? I would like to give a shot since it seems like it should bloom...given how nicely it once did?

    Bookmark   April 28, 2012 at 9:52PM
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woodyoak zone 5 Canada(5b)

The graft union would be near the base, so if you prunely relatively high, you should still have the original plant even if you also have a lot of root suckers. Do you know/can you tell what the original plant was - i.e. was it Chinese, Japanese, or American wisteria? Not that it matters a lot probably...! As a general rule, Chinese wisteria twines counterclockwise and Japanese and American twine clockwise. Chinese wisteria flowers start to bloom before the leaves expand while Japanese wisteria flowers after the leaves expand. American wisteria is usually the latest to bloom and blooms on 'new wood' rather than the 'old wood' for the Asian ones. So the hard prune shouldn't have impacted the blooming much if it was American. The flower racemes of Japanese wisteria are usually quite long while the Chinese ones are shorter. There has been a lot of both accidental and planned cross-breeding between the species so ID can be iffy...

If you intend to keep the vine, then controlling the root suckers and shaping the plant into something that is of a manageable size to control is the place to start. We use a long-arm pruner to keep our Chinese and Japanese ones pruned to manageable size. We do not let them get out of reach of the pruner - we took 12-18" off the top of the Chinese one this spring because it was getting too tall.

Our Japanese one was planted 5 years ago and this is the first spring it has had flowerbuds. The Chinese one is 12 years old and has been blooming since it was 5 years old. Pruning is almost a weekly task here once the new leafy growth starts - all 'whippy' new growth is pruned back into the framework we want to keep; we monitor for root suckers and remove them by digging down and tearing them off the roots to tear off the budwood; after the leaves drop in the fall, all seed pods are removed to ensure they don't seed around. You MUST NOT neglect your wisteria if you plan to keep it! It's beautiful in bloom but a monster if not controlled.

    Bookmark   April 29, 2012 at 11:11AM
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