By now, you’ve probably seen the uber-fabulous photos of the wisteria tunnel at Japan’s Kawachi Fuji park.
Though the photos seem to suggest otherwise, the key to successfully growing wisteria is a combination of abuse and neglect.
Wisteria is one of those plants that needs to work to earn the gardener’s love. If you give your love first, forget it. No, wisteria you need to challenge, curse at, take your anger out on and make it work for your affections. Sounds like a pretty perverse relationship, eh? Well, welcome to horticulture. It’s not the first one you’ll engage in if you garden for very long.
Wisteria must never be fertilized.
Applying fertilizer encourages copious amounts of foliage to grow at the expense of the flowers. If you grow wisteria in a lawn, flower bed, or other mixed situation where it may absorb nutrients from a fertilizer treatment applied elsewhere, you’ll need to stop fertilizing that area for best results.
Wisteria must be pruned. Brutally. But of course, at the proper time. Here in February, any flower buds that your wisteria is planning on unfurling this spring are already there on the plant. So don’t dare cut a thing right now unless you take a look at the bare stems and can positively discern the leaf buds from the flower buds. If so, sharpen your shears and cut the leaf buds back by half – this will allow the plant to direct more energy into extra-fabulous inflorescences. If not, go back indoors and look at another photo of Kawachi Fuji and keep your fingers crossed:
However, this summer, plan to prune back the long thin growth the vine will put out frequently. Cut them hard, and cut them often. Remind it that it is supposed to be a flowering plant, not a foliage plant.
Buy a Grafted Plant
If you are buying a new plant, make certain that you are buying a grafted plant. This will probably require a trip to a local nursery that specializes in woody plants and talking to someone who knows a thing or two about their stock. However, it is worth the effort: seed-grown wisteria may take a decade or more to begin flowering, and those ten years leading up to it is still going to require the maintenance guidelines I’ve described so far.
Wisteria is a powerful twining climber. It is part boa constrictor, squeezing out anything it encounters in a race to the sunshine. So make sure you have a very, very strong support for the plant from the beginning. I have heard (and, in fact, seen some evidence) that wisteria flowers at a less mature age if it is allowed to reach a period of horizontal growth sooner than later. It is most often planted on an arbor or a pergola and must grow up an 8-10′ upright post before it reaches the top and can grow horizontally – as long as it is growing upright, it will not flower (or will flower very little). So if you can rig up some kind of roof-top planter or very low support, you’ll be one step closer to your own Kawachi Fuji.
I advocate neglect and well-timed abuse for the best performance from wisteria – but I do stop short of the vicious root-pruning or stem gouging methods that some recommend. These may induce flowering for a season but are hardly recommended maintenance for any kind of plant. Besides, wisteria is subject to a host of pests (oh, the leafhopper damage I’ve seen on wisteria) and diseases (especially disfiguring viruses) and will become more susceptible to them if stressed.
Wisteria are invasive
Finally – and this is really, really important – as hard as it may be to believe, Japanese and Chinese wisteria are invasive in many parts of the U.S. However, there is actually a native species (W. frutescens) that can be used instead, and it is actually quite lovely. Of special note is the cultivar ‘Amethyst Falls,’ a rebloomer with fabulous color and lovely flowers:
Maybe wisteria is so reluctant to perform because it is still sulking over the error in its name: It was originally supposed to be called Wistaria, after the famed physician Caspar Wistar, but an error in transcribing it to the International Code of Botanical Nomenclature has made it Wisteria forevermore