The wisteria blooming now are spectacular. I almost forget about them during the dormant season as I’m not fortunate to have one in my garden, but once they start to flower they seem to be everywhere, even growing up into the redwoods in many places. Who hasn’t longed for their fence, arbor or pergola to be covered with fragrant wisteria? Bees and hummingbirds love them, too.
Those you see most often are probably Cooke’s Purple with clusters of fragrant blue-purple flowers 20 inches long. It blooms twice per season, which is a plus, but there are many other varieties available now.
Chinese wisteria like Cooke’s Purple can take up to 20 years to mature enough to produce flowers, but once it has matured, the plant is very long lived and can live up to 100 years.
Amethyst Falls American Wisteria has become very popular because it’s perfect for smaller spaces. Growing to only about a third of the rate of Asian wisteria, it blooms at an early age with lightly fragrant purple racemes. Grow in a container for your porch or patio, train up an arbor or trellis or train as a small free-standing tree.
Another smaller variety to try is Shiro-Beni Silky Wisteria with its highly scented dark pink smaller flowers that open all at once. Consider also Iko Yama Fuji Silky wisteria with long violet buds that open to highly fragrant pale lilac blooms in late spring. Also beautiful is Kaptain Fuji, a white silky variety.
Japanese wisteria like Texas Purple, White and Pink Japanese wisteria are most effective when grown on pergolas so their long flower cluster can hang freely.
Kentucky Blue Moon is one of the hardiest wisteria. It blooms up to three times in a growing season once established, producing beautiful foot-long racemes of fragrant, pea-like lavender-blue flowers.
Wisteria are 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 clearing 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 control their 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.
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 if there is an over abundance of luxuriant growth. Over feeding also ends up giving them the means to become an unmanageable monster. If you have trouble getting your vine to flower, an application of a high phosphorus fertilizer may promote blooming.
Maintaining a wisteria requires some diligence, but the reward is worth the effort. Remember this especially during the winter pruning season to make summer maintenance easier. If you find that the wisteria vine has invaded a nearby bed, cut roots with a shovel below the soil line to control any that have wandered.
All parts of the wisteria vine contain a toxin known as wisterin, which can cause stomach upset. Growers should also be wary of pets and children eating the flowers or seed pods.
Jan Nelson, a landscape designer and California-certified nursery professional, will answer questions about gardening in the Santa Cruz Mountains. Email her at ja******@ao*.com, or visit jannelsonlandscapedesign.com.
