A wisteria is one of those plants that you either love or dread. One of nature’s most resilient survivors they are able to withstand and recover quickly from difficult conditions. To some they are a little too tough for their own good with a growth rate rivaling bamboo during the summer. If you dream of a wisteria-covered pergola shading your patio here are some maintenance tips that are sure to keep both gardener and vine happy.
Wisteria are so vigorous they can be pruned at any time, keeping them in bounds and to clear out unwanted or dead growth. Prune out any stems you see extending into eaves, windows or shingles. If yours has gotten away from you, you can even prune it down to the ground and start over with training although you’ll have to wait a few years for your vine to bloom again.
To their control size major pruning is done during the dormant season. Start by trimming the long tendrils that grew over the summer back to about 6 inches from the main trunk. Cutting the tendrils back in this way will initiate flower bud development, neaten the plant up, and show off the attractive trusty, gnarly character of the vines.
Pruning during the dormant season will also give you a fighting chance of keep your wisteria from getting into mischief. As you know if you have a wisteria, those long tendrils are capable of growing another 25 feet during the summer.
Whatever time you do renovation pruning remember the response of the wisteria to aggressive pruning is to literally explode with new runners. They put energy into new vegetative growth at the expense of flowering. Make sure you keep up on ongoing maintenance pruning by removing all unwanted runners right to their point of origin. Then prune back the others to 3 buds or sets of leaves. Repeated pruning of these runners is what will eventually give you spurs of wood, short laterals that in turn will provide you with flower clusters. You need to prune these runners all season long which ends up being every 3-4 weeks.
Do not fertilize your wisteria. They do not flower well is there is an over abundance or luxuriant growth. Over feeding also ends up giving them the means to become un unmanageable monster. If you find the wisteria vine has invaded a nearby bed, cut roots with a shovel below the soil line to control any that have wandered.
Maintaining a wisteria requires some diligence but the reward is worth the effort. Remember this especially during winter pruning season to make summer maintenance easier.
Which variety of wisteria should you get to cover your arbor, pergola, tree or other structure?
Chinese varieties such at ‘Cooke’s Special’ has clusters of fragrant blue-purple flowers 20 inches long. This variety can re-bloom which makes it a favorite.
Japanese wisteria ‘Caroline’ blooms early with mauve flowers. ‘Royal Purple’ (also known as ‘Black Dragon’) has sweetly scented dark purple flowers. Japanese wisteria are most effective when grown on pergolas so the long flower cluster can hang freely.
Silky varieties produce a profusion of short, 6 inch, fat clusters of strongly scented flowers that open all at once. They have velvety seed pods and bloom best in full sun.