Wisteria - no blooms

Discussion in 'Outdoor Gardening in the Pacific Northwest' started by Paul Cornthwaite, Sep 5, 2019.

  1. Paul Cornthwaite

    Paul Cornthwaite New Member

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    I live in Port Alberni, and have two seven year old wisteria vines, planted as a feature five years ago adjacent to a pergola with a southern aspect and a path running in front. I have not fed a nitrogen rich food and they have lots of irrigation. I have never had the inkling of a bloom but lots and lots of foliage and runners. Can you suggest any clue as to the problem and what might I do as a last resort before I chop them down.
     
  2. Ron B

    Ron B Paragon of Plants 10 Years

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    If raised from seed it is likely they are simply not old enough to bloom yet, at only 7 years in place. Also a percentage of seed-raised wisteria grow indefinitely without flowering, as though they are never going to. Otherwise wisteria plants that come from the nursery with flowers on them or bloom soon after purchase and planting are vegetative propagations (clones) that have the sexual maturity of the parent plants.
     
  3. Michigander

    Michigander Active Member

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    Age is important, but being root-bound or root-restricted is just as important. If planted out in open ground with no competition, they can get big and take forever to bloom, like 30 years. Once they bloom, they will from then on. The rule is never buy one unless you see it in bloom. Shovel pruning may work, but you may have to do it many times: circle it 360 with a spade close-in enough to reduce the size of the root system any time you see new growth, up to several times a season.

    There is also an inverse correlation between the balance of mass between the vines and the roots: the roots will gladly replace all pruned off vines, to the best of their ability, so pruning vines is counter-productive when shovel pruning. Yes, that means all those rampant vines need to be left to grow out of control an out of bounds until the balance of power has shifted to you. Think of this as putting it in the position of a 40-year-old woman who has never had a child, but really wants one. Propagation is the point of living, but Wisteria wants to take over the world first. (Unlike women?)
     
  4. Ron B

    Ron B Paragon of Plants 10 Years

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    So in other words how long some seedlings take to reach sexual maturity is in fact the problem.
     
  5. Michigander

    Michigander Active Member

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    Yes. And the problem will eventually evolve and/or be ameliorated by how the plants are handled in-between now and when they come of age because there is no magic age at which they flower.
     
  6. Paul Cornthwaite

    Paul Cornthwaite New Member

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    Thanks for the information. If I was to keep the vines how would you suggest I prune them - until they bloom?
     
  7. Michigander

    Michigander Active Member

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    I would suggest that you shovel prune them every May 1st and June 21st and let the vines grow ~rampant~ until they flower. After they flower, prune the vines hard to your desired size and leave the roots alone. Take notice of what the flowering spurs look like and do not prune them. The flowering spurs will build and eventually die and be replaced by others, so only prune them when they are dead. Long term, prune hard after blooming and as often and as much as it takes to keep in-bounds. Periodically, shovel prune by digging a trench 360° around the crown and just turn what's there over, maybe removing larger pieces of root.

    They need supports that they can twine around that are substantial. You should consider installing hooks or poles or whatever hardware suits your situation, all of which needs to be accessible, hopefully from the ground.
     

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