Open Association of Landscape Industries
Hard-pruned wisteria not flowering
Has anyone got more experience with wisterias who could help here?
I have a client with a very old, at least 50 years, wisteria that was completely covering their roof. They wanted it cut right back, and their tree surgeon reduced it to below first-floor window height two years ago. I explained at the time that they were going to affect the plant's flowering by cutting it back by around 75%, but it's not flowered at all for the second spring now.
It's still very healthy, obviously throwing masses of new growth that I'm thinning and training in. What I can't understand is why the established branches that weren't cut back have stopped flowering?
I've now got a client who has forgotten that I advised them it would take years to recover, and are blaming me for not telling them it would stop flowering.
Replies to This Discussion
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Permalink Reply by John on -
It can take 3 to 4 years to recover from a hard pruning. I guess
the plant has decided to put its energy into new regrowth rather
than flowers. Its root system will be able to support
an extra 75% area of branches, so capillary
water pressure may have a bearing on this. The plant needs to be balanced
so new growth comes first.
However it has not been a great year for wisteria in general.
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PRO MemberPermalink Reply by Gary RK on -
Paul, would the following help from the esteemed RHS website (always carries a bit of weight ;-)
Drastic pruning
Some climbers and wall shrubs tolerate drastic pruning and can be cut down to approximately 30cm (12in) from ground level. This drastic pruning means that flowering will take several years to resume, but allows new green shoots arising from the base to be trained into a new and rejuvenated framework.
Examples of plants that re-grow well from drastic pruning include: Abelia, Acacia, Ampelopsis, Aristolochia, Azara, Campsis, Celastrus, Cissus, Clematis, Cotoneaster, Hedera (ivy), Osmanthus, Pyracantha, Ribes sanguineum, Rosa, Vitis and Wisteria."
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Permalink Reply by John on
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Some people say that the new whippy growth should be cut back to five or six leaves
in August and then back to three buds in the late winter.
The retraining of the really long growth is a different matter, as it is required
to grow and form the framework. I am not sure how large this Wisteria will be allowed
to grow now, but when training along walls, I have always allowed a few shoots to grow along
the ground at the base of the wall behind other plants, sometimes getting to a length of
twenty five feet. They are easily picked up and attached to the wall, and cut back by about
a quarter to promote lateral growth. Two years later with correct prung it should start flowering.
Duncan said:Cut the new growth back to eight buds/nodes mid year, then later in winter cut all of them back to three buds.
Learned that from a christmas cracker that one. ;-) It should flower next year if you do that.
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PRO MemberPermalink Reply by Paul McNulty on -
Thanks. There's still masses of plant covering the front of the cottage, which is probably 12 or so metres wide, up to first-floor window height. It's this they are disappointed about losing the flowers from, as it wasn't affected by the hard pruning in their eyes. Despite me telling them it would take years to recover!
It's always been pruned correctly, perhaps I just need to train new growth in and gradually replace all the older stems. Good idea to run them along the ground, John.
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Permalink Reply by John on
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RHS recommendation/advice,
Water between July and sept if dry as this is when the flower buds are
forming.
Sharp frosts can also damage the flower buds and cause them to drop before
they open.
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Permalink Reply by Geoffrey King North Yorkshire on -
Up here in North lands, where we care for a number of Wisterias, pruning them to six buds in mid summer and 4 buds in mid winter, we note that branches on South facing walls flower several weeks before West facing. And that they have been slow to emerge after the recent colder weather.
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Permalink Reply by N. F. Trees & Gardens on -
I hard pruned ours a few years ago, and gave it several feeds of potash.
Flowers a treat!
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