If you’ve ever seen a wisteria in bloom, you will know why many gardeners have a penchant for growing them. As a child, I remember my grandmother’s wisteria creating a beautiful canopy of dangling pendulous racemes on her trellis. It was a sight to behold, and to smell, as they were wonderfully fragrant – just as enchanting to me now as an adult as it was back then.
There are about ten known species of Wisteria, with numerous cultivars associated with each that are native to the eastern United States and eastern Asia. One of my personal favorites is Kentucky wisteria (Wisteria macrostachya), the type my grandmother grew. Read on to learn more about caring for Kentucky wisteria vines in the garden.
Kentucky wisteria is notable because it is the hardiest of wisteria, with some of its cultivars rated for zone 4. The majority of Kentucky wisteria (such as cultivars ‘Abbeville Blue,’ ‘Blue Moon’ and ‘Aunt Dee’) feature a color that falls in the blue-violet spectrum, the one exception being the cultivar ‘Clara Mack’, which is white.
Kentucky wisteria vines bloom in early to midsummer with tightly packed panicles (flower clusters) typically reaching 8-12 inches (20.5-30.5 cm.) long. The bright-green lance-shaped leaves of Kentucky wisteria are in a pinnately compound structure with 8-10 leaflets. The formation of 3- to 5-inch (7.5-13 cm.) long, slightly twisted, bean-like, olive-green seedpods begins in late summer.
This deciduous woody stemmed twining vine can grow 15 to 25 feet (4.5 to 7.5 m.) long. Like all twining vines, you will want to grow Kentucky wisteria vines on some support structure such as a trellis, arbor, or chain link fence.
And, to set the record straight, there is a difference between Kentucky wisteria and American wisteria. While Kentucky wisteria was originally regarded as a sub-species of American wisteria (Wisteria frutescens), it has since been classified as a separate species due to its longer blooms and because it has a higher cold hardiness rating than American wisteria.
Caring for Kentucky wisteria is easy, but getting it to bloom may prove to be a challenge. Such is the nature of wisteria, and Kentucky wisteria is no different! It is best to improve your odds from the onset, meaning you may want to avoid growing Kentucky wisteria from seed. Wisteria plants started from seed can take 10-15 years (even longer or perhaps never) to bloom.
To considerably shorten the time to flowering and a more reliable path to flowering, you will want to either obtain or prep your own cuttings, or acquire good quality plants from a certified nursery.
Your Kentucky wisteria planting should occur in the spring or fall and be in soil that is characteristically moist, well-draining, and slightly acidic. Kentucky wisteria in gardens should be in a location that is full sun to part shade; however, a full sun location receiving at least six hours of sun each day is preferable as it will help encourage better bloom growth.
In addition to proper lighting, there are other ways to help elicit the blooming of Kentucky wisteria in gardens, such as a spring feeding of superphosphate and routine pruning in summer and winter.
Even though wisteria is considered to be drought tolerant, you will want to keep the soil consistently moist during the first year of growing Kentucky wisteria to help the root system get established.
Long, hanging clusters of flowers make wisteria (Wisteria floribunda) a never-to-be-forgotten sight in late spring. Wisteria floribunda is hardy in U.S. Department of Agriculture plant hardiness zones 4 through 9, but this twining vine is only one of several wisteria types that grow in the United States. Another type is Wisteria sinensis, which is a slightly more tender plant that’s hardy in USDA zones 5 through 9. However, both Wisteria floribunda and Wisteria sinensis are invasive in some states. Before planting a wisteria vine in your garden, check that the plant isn’t invasive in your state and that it can survive the lowest winter temperatures and highest summer temperatures in your hardiness zone.
Wisteria sinensis, growing in the formal gardens of Hampton Court Palace.
Photo by: Image courtesy of Felicia Feaster
Image courtesy of Felicia Feaster
Wisteria sinensis, growing in the formal gardens of Hampton Court Palace.
The fragrant panicles of Chinese wisteria resemble grapes. Yet, as much of the country has come to realize, wisteria — like kudzu, honeysuckle and other flowering beauties — can be an utter nightmare. The vine has been described as invasive in at least 19 states from the Illinois to Texas, so plant with extreme care.
Wisteria sinensis is a rapid growing deciduous climber hardy to zone 5. Chinese wisteria is an aggressive plant that can potentially take over an area of the garden. So consider yourself warned: Chinese wisteria can be maintained, but will require at least a monthly pruning to control the growth.
You should position your wisteria plants to get ample amount of sunlight. These plants need a minimum of six hours of full sun every day. The plant can grow well in partial shade, but this placement may result in few or no flowers.
While purple wisteria vines can do well in most types of soil, it still requires enough nutrients to sustain. Amend your soil with an organic compost if it only holds low amounts of nutrients or if it appears stuck in a very poor condition.
Wisteria vines like slightly acidic and well-drained soil.
This lushly blooming vine also craves for fertile, consistently moist, but not soggy soil.
You can plant your new wisteria in the springtime and enjoy the foliage through the summer. Alternately, you can plant Wisteria vines in the fall, allow it to enjoy winter, and emerge the following spring.
When you plant, dig a hole just as deep as the existing root ball. It should measure about three or four times as wide as the root ball. Wisteria grows fast and tends to sprawl, so give each plant ten or fifteen feet of space to grow.
Keep Wisteria vines away from each other and other plants. If given the opportunity, these flowering vines will quickly rampage over trees and shrubs and cause their untimely demise.
Few if any climbing plants come near the beauty of wisteria, whose long, pendulous, blue flower clusters arrive in early spring, creating a spectacular show combining grace and charm with powerful visual impact. In some areas the common Chinese wisteria has become an invasive plant, so why not grow a gorgeous form of the American native wisteria instead? Equally beautiful, it is also significantly hardier, making growing and blooming this gorgeous plant possible even in zone 4. For hiding ugly fences nothing can match it, and for covering larger pergolas it is in a class of its own. The sweetly scented blooms will soon make its return each year feel like a visit from a beloved family member – it’s time to welcome the Aunt Dee Kentucky Wisteria into your garden.
A vigorous, deciduous climbing plant, the Aunt Dee Kentucky Wisteria sends out long twining stems covered in leaves that are up to 12 inches long. They don’t look large, though, because they are divided into 9 to 15 small leaflets, each between 1 and 2 inches long, arranged in pairs along a central leaf-stem, with one leaflet at the end. These graceful leaves create a picture of glossy-green lushness all summer and turn yellow in fall. The stems become woody and thicken, until the base of the plant forms a stout trunk, and the strong branches are covered with leathery, gray-brown bark. Although climbing, a mature plant is substantial and heavy, almost tree-like, so make sure the support you grow it on is sturdy and strong. It is also possible in time, with training, to develop this plant into a striking free-standing bush.
In spring, before, and as the first leaves appear, the Aunt Dee Kentucky Wisteria will be in full bloom. The wild form of this plant has small flower clusters, but this variety has large ones, between 8 and 12 inches long, hanging in abundance from the bare stems. Each raceme has many individual flowers on it, and each one is shaped like the flowers of peas, with a large, flat, upper lip and a smaller, folded, lower lip. They are colored a delicious lilac-blue, with the lower lip a darker shade than the upper one. A sweet perfume flows from them, and a plant in bloom is a glorious sight. When the flowers fade, they are replaced by a cluster of pods, 2 to 4 inches long. These are light green in summer, becoming glossy brown by winter, adding a touch of interest at that time. The seeds inside are not edible. Sometimes additional flowers are formed in summer, bringing further interest.
The Aunt Dee Kentucky Wisteria is the perfect plant for covering unsightly fences or large dead trees. It will grow to 20 or even 30 feet tall, but it is not as vigorous as the Chinese wisteria, Wisteria sinensis , which can be a troublesome bully in all but the largest gardens. It is an ideal choice for growing on a large pergola, or on a trellis against a wall. With some training it can be made to completely cover a wall of a house, and it makes a glorious sight. Plant it to grow into an old tree in an open woodland garden It can also be grown in a large planter, and even made into a bonsai plant of great beauty.
Full sun is the ideal spot for the Aunt Dee Kentucky Wisteria to grow in, although it will grow in partial shade, but with fewer blooms. Unlike the Chinese wisteria, the flower buds of this plant are hardy in zone 4, where it will bloom profusely. It grows well in any moist soil, even wet ones, and in acid soils and clay soils too. It is also resistant to road salt. Once established it has some drought resistance, but dry, sandy locations are less suitable for this plant. It is normally not bothered by pests or diseases, and it will even grow into a black walnut, a tree well-known for making the soil around it toxic to many plants. Fertilizer is normally not necessary and feeding this plant may make it flower less.
Although it can be left to grow naturally on a large support, regular pruning is the secret to success with the Aunt Dee Kentucky Wisteria. After flowering and the first flush of new growth, trim back all unwanted stems to 6 inches long, cutting just above a leaf. Train some stems to make longer branches, as needed, to cover the pergola or support you are using. Then in winter prune again, cutting all the side stems from the main branches back to just 2 or 3 buds. The larger buds are the ones that will produce flowers, and regular pruning will give you the most blooms, keeping your plant neat and attractive at the same time. It is also possible to train young plants into an upright bush, using stakes. Once the stems thicken it will be more-or-less self-supporting. Then with regular pruning it can be maintained as an exotic, oriental-looking shrub of considerable beauty. The same can be done with a plant in a large planter or pot.
The Aunt Dee Kentucky Wisteria is a selected, cold-hardy form of the American wisteria, Wisteria frutescens . That plant grows throughout the east, from Michigan and New York, south into Florida and Texas. A unique form, called the Kentucky wisteria, is found in that state, and in other parts of the southeast. It is sometimes called Wisteria frutescens var. macrostachya , and sometimes simply Wisteria macrostachya . It is different from the American wisteria because the blooms are scented, and for other minor features. The variety called ‘Aunt Dee’ is remarkable for the much larger flower clusters, and its ability to bloom in zone 4, which makes it a great gift to northern gardeners. If you love wisteria in bloom, but fear being taken over, then this is the variety to choose. Rarer forms like this one are hard to come by, and our limited stock won’t last long. Order now, you won’t regret it.