Wisteria 'Blue Moon' pruning help needed!

10 years ago

last modified: 10 years ago

About 3/4 years ago we purchased a 'Blue Moon' wisteria that my DH spotted at a local garden center. He said he always loved wisteria and was even willing to build an arbor, which then he did. The arbor is made from 4x4 pressured treated wood and measures 8 feet tall, 6 feet wide, and 3.5 feet deep.

We need some advice as to whether or not the wisteria should be pruned for two reasons.

First of all, there is some kind of scale growing along the base of the trunks. Is this typical for wisteria or a problem because of the multiple trunks? Are there too many main trunks? The first two photos show both sides of the base.

The "front" side

The "back" side

Secondly, will the growth of this vine eventually break the arbor? The next photo shows growth along the back post. I can only imagine what this will be like in 3 more years!

The top of the arbor, below, is a tangle of branches. Should any of these be thinned out? If this does need pruning, could we do it now while the branches are bare and easier to see or wait until after first flowering?

We live in z6b along a tidal river that runs into Long Island Sound. The arbor is in full sun at the river end of our yard. Thanks for any suggestions!

Molie

Featured Answer

woodyoak zone 5 southern Ont., Canada

10 years ago

I was just doing some reading about Blue Moon. I have sometimes thought I should try one.... This one apparently flowers on new growth (versus the Asian ones mainly flowering on 'old wood') so these flower a bit later (in June) than the Asian ones and pruning is supposed to be miminal (I doubt it!) and left to after the first flush of flowers. So if you're going to prune yours, it sounds like you should wait until the end of June to let it have time to flower if it's going to.

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Comments (6)

NHBabs z4b-5a NH
10 years ago
Molie, the scale at the trunk base is just lichen. It is only using the Wisteria as a surface to grow on and it doesn't harm the plant at all, just adds character and the look of age to the trunks. You will see lichens growing on tree trunks as well. Sorry I can't help with the Wisteria pruning.
moliep thanked NHBabs z4b-5a NH
wisconsitom
10 years ago
Right^...harmless and interesting lichens. As to pruning, I'm no wisteria expert but given that this is a vine, there is no reason to think the plant is producing too many stems. That's what you want it to do-produce lots of stems. As to the other pruning aspects, I doubt it is mandatory, but I also doubt you can hurt this plant much with a little pruning. I just don't see the necessity. Perhaps a more wisteria-experienced person will pop in with more info.
moliep thanked wisconsitom
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gardengal48 (PNW Z8/9)
10 years ago
The more one prunes a wisteria, the better it flowers!! So actually, consistent annual pruning as well as summer care (removal of very fast growing whippy shoots) DOES make a big difference. All those small stems need to be headed back - it is the laterals they produce that will carry the flowers, much like the laterals from the large arching canes produce the flowers on a climbing rose.

The best synopsis I have encountered for dealing with wisteria pruning requirements was produced by a local organization that specializes in in teaching homeowners the right way to prune and how/when to do so. The author, Cass Turnbull, is a certified arborist as well as being an educator and all round horticulturist. A very skilled lady!!

Plant Amnesty's guide to pruning wisteria.
moliep
Original Author
10 years ago
Thanks for the tips on the lichens and for that pruning guide, gardengal. I've read it and it's so informative that I'll print it for future reference.

We'll go out and see which parts of the vine should be cut back to produce more flower-bearing "hands." That term is so descriptive and really explains what can be done to produce more flowers. Our wisteria actually is a mass of long, whipping stems that have grown back on to each other, and so I'm guessing we need more "hands."
Charles Gialet
6 years ago
Would any one be able to tell me what the problem might be with my blue moon wisteria. I planted it about a month ago but it seems like the leave are slowly turning this yellow color.