When in bloom, wisteria is a showy, colorful, fragrant vine that can add depth and interest to your garden. Best grown along a pergola or fence almost like a hedge, wisteria can be really invasive, so be sure to keep it in check with regular pruning. For all zones, cut trailing vines throughout the year and then cut back main branches to three buds in the dormant season. This will encourage more blooms. Hardy from USDA Growing Zones 3-9, wisteria will lose its flowers and leaves in the colder months. But in the spring and summer, the vine will produce 6-inch long pods of blue, pink or white flowers that hang like teardrops off the vine.
Look for a winter-hardy variety of wisteria, such as Blue Moon of the wisteria floribunda species, which should withstand the winters and come back beautifully in the spring. You may plant in the ground or in pots, but during the winter months, bring the pots in and cover the in-ground vines with mulch and plastic for extra protection. As it gets colder, the vine will drop its bloom and leaves and it will look like a barren warren of branches. This is the time to cut wisteria back.
Zones 5-6 may still have tough winters, so a cold-hardy wisteria is your best choice, though most varieties should survive Zone 6 winters with proper care. Vines should bloom from late spring-early fall, during which time they require moderate watering and pruning back of trailers. As winter approaches and the plant drops its blooms and leaves. For newly planted vines, it's likely you'll cut back to the main stem, which you can cover with plastic piping or wrap with plastic to protect it from the cold. For larger plants, cover root area with mulch and as much of the plant as you can with plastic or other protective covering to winterize.
In these warmer zones, wisteria is prevalent and shouldn't need too much care. You may plant any species, but it can become invasive if not properly pruned. Wisteria is just about drought tolerant, but should be watered weekly and planted in nutrient-rich soil. The vine should bloom from mid-spring-late summer before going dormant and requiring pruning. While it is not necessary to winterize established wisteria in these zones, it is a good idea to cover the main root of a new vine with plastic tubing or the entire plant with mulch and plastic covering.
Wisteria love Zone 9 and should flourish in this area with little care. Wisteria should be planted in nutrient-rich, well-drained soil with a lot of room to grow, as these vines are really invasive in warmer climates and may strangle small trees. The vine will bloom throughout the spring, summer and early mid-fall before dropping its leaves and dying back to what looks like a bunch of sticks. In early spring, the vine will begin to come back.
A member of the pea family, wisteria is a deciduous vine that has a long life and may be grown as a vine, tree or shrub. Older plants are nearly drought-tolerant and can withstand hot and humid summer heat, though they should be watered weekly. Once established, these plants rarely need fertilizing. When planting new wisteria, be aware that it may take a few years before blooming.