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On a warm May evening as I sit under the pergola, enveloped in the heady perfume from the clouds of white wisteria overhead, it is easy to just be in love and forget the downside of my relationship with this strong-willed vine.
In the back yard the wisteria variety Macrobotrys is also blooming – nearly scentless with pale mauve flower clusters (racemes) up to 5' long. A gauzy curtain, it drapes languidly across three arbors.
On my front stoop in a six" pot, another cultivar, ‘Geisha’ has bloomed. I’ve been looking for this cultivar for the past eight years and am building yet another structure on which to display its shower of very narrow, nearly blue tightly-packed flowers. Love or mania, all of this is occurring on a less than 50’ x 100’ urban lot. It’s getting out of hand! I am eyeing the north fence and thinking that it too might use a nice Wisteria to cap it…
Passion is fine, but in the case of Wisteria we recommend an arranged marriage. Step one in your love affair with this plant has got to be housing. Sorry, this baby demands commitment from the start with no courtship period. Know where you want the vine to go and just how far you will let it grow. Don't think you will just let it grow for a few years and then prune it to shape. Discipline from day one is the way to go here.
Wooden support structures should be sturdy and well built of at least 2" x 4" material or even pipe. Lattice panels are of no use as the vine will destroy them in nothing flat! Allowed to weave in and out as a lithe tendril, it will expand destructively as, like us, it thickens and hardens with age. Vinyl coated multi-strand steel cable is very useful in training as long as the hardware used to attach it is substantial. Whatever you use as support, bear in mind that this vine will eventually become tree-like, woody and heavy.
As the new plant grows, keep your eye on it. Sure, it is going to be beautiful, but mind the mischief. The worst thing I've encountered over the years was a tiny young shoot that had worked its way into the leading of a turn-of-the-century (the last one!) window and had grown in girth, and shattered the vintage glass. Watch carefully, realizing that you don't want it behind a downspout, shingle or shutter. Think of the word "pry"; and you've got the picture. Wisteria is destructive in the wrong place, heavenly where you want it.
'Geisha' - Mike’s favorite. Abundant pale blue and periwinkle flowers with chartreuse blotch. Light scent. Racemes to 10" long with densely packed flowers.
'Hon Beni' ('Rosea') - Racemes up to 18" long of pale and mauve pink, with yellow blotch.
’Longissima Alba’ (’Shiro Noda’) - All white flowers with light scent, on racemes up to 3' long.
’Macrobotrys’- Some of the longest racemes of flowers, up to 5' long, but more commonly to 3'. Flowers are lavender.
'Violacea Plena' - Racemes up to 14" long house some of the darkest petals seen on a wisteria. Double flowers pack petals along the raceme, blending dark and light petals together to form a fluffy, lilac-like effect. Foliage turns a nice butter yellow in fall.
'Amethyst' - Darker more reddish violet flowers are among the most fragrant. Fewer flowers on the racemes, which are up to 6-7" long. Young foliage is deep bronze, turning green with poor fall color.
'Caroline' - Probably a hybrid, Caroline blooms early, often before other wisteria. Short racemes are lavender with darker purple and highly scented. Vines twine clockwise, like Japanese wisteria.
'Cooke's Purple' (Cooke's Special) - One of the most floriferous with spring racemes up to 18" long with repeat flowering in summer on shorter racemes.
'Kofuji' - Mini Wisteria - Tiny lavender flowers, tiny green leaves, small stature, but still with good vigor. Lends itself well to bonsai.
'Prolific' - Covered in blue flowers before leaves appear. Blooms young, heavily and repeatedly during summer, with a sweet perfume.
Text by Mike Wallace
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5050 SE Stark, Portland, OR
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Genus: Wisteria – Named for Casper Wistor (1761-1818), Professor of Anatomy, University of Pennsylvania
Common Name: Wisteria
Origin: China, Japan, Eastern United States
Characteristics: Extremely fragrant flowers are pea-like, held in terminal or axillary clusters, or racemes. Bloom occurs in April-May. Ferny light green foliage is sometimes covered in fine white hairs. Vines attach by twining, growing very fast, and developing a thick tree-like trunk in time.
Culture: Full sun to partial shade, with better flowering in sun. We recommend adding soil amendments at the time of planting to increase soil drainage. Regular water and fertilizer are important for such a vigorous plant.
Bound feet - Container Growing Many people ask us if they can grow this vine in a pot on a deck or patio. The answer is one of those yes-and-no answers.
The root system of a massive vine wants to be equal in size to the “above ground” portion of the plant. Grown as a vine, Wisteria will outgrow a container quickly. The roots will just need more space to spread out in order to support such a large mass of leaves and flowers.
However, if a Wisteria is grown with the idea of bonsai or topiary, it is possible. Regular pruning to maintain a smaller plant is the key. That is pruning not only in the visible portion of the plant, but also in the roots.
Pruning: When your training program provides you with the main structural wood that has developed from long running shoots you have tied or trained to your support system, you will want to do an annual structural pruning in winter to maintain the basic skeleton.
You can cut back small wood (pencil sized or so) and unwanted spring and summer growth at almost any time. A simple rule is to cut back to 2 growth buds (2 leaves in spring and summer) on growth that is well placed for bloom production but is not going to be useful as permanent long vine wood. When in doubt, cut back to two buds above the point where the growth originated. This often removes most of the tangle of summer growth.
Carefully untangle and tie any long growth in summer that you may want to keep for future training. It will harden into useable wood by the time you are ready to do next year’s deciduous phase pruning.
On my pergola there are three evenly-spaced parallel main stems running 24 feet each from south to north. From these are growing all the shortened blooming branchlets which have been created using two bud rule of thumb described above.
As you become more comfortable as a Wisteria pruner, you may begin to remove some of the bloom wood in order to create a harmony between open space and plant. Often the empty space along the vine is equally important to the blossom-laden branches.
Pests and Diseases: Wisteria are fairly unfussy, and really seem to thrive in our climate. They can be susceptible to fungal and insect problems, but they are typically not life-threatening. Aphids and scale insects have been observed on some plants, as well as thrips and mites. Powdery mildew and leaf spot can cause minor cosmetic damage, and crown gall can be problematic.