I have arbors on three sides of my porch and have Wisteria sinensis (10 years old) on one as well as Wisteria floribuda (10 years old) on the second. It is May so they both are in full bloom. When you sit in the swing in the evening and the air is still it is the most amazing experience.
If you have not grown Wisteria there are a few things you should know: Wisteria is a very vigorous, twining vine. You will need a commitment to keep the plant in the bounds of the garden or chosen space. Among the prized attributes are hardiness, vigor, longevity and the ability to climb high. The flowers are 12 to 20 inches large, pendulous, and occur in the spring. Flowers are pea-like and may be white, pink, lilac-blue, bluish-purple or purple in color. The fruit is a long, green flattened pod that is not particularly ornamental. The plant climbs by means of twining stems and has alternate, pinnately compound leaves. Older, established plants may have a twisted, woody trunk several inches in diameter. Plants that have been grown from seed remain in a long juvenile stage and often do not bloom for 10 to 15 years or longer. Plants that are grafted, and plants grown from cuttings or layered from a flowering plant will usually begin flowering within 3 to 4 years. I have three on arbors around the porch and on an arbor in the garden; each took 4 years before they bloomed.
Two species of wisteria are typically grown in home gardens: Wisteria sinensis or Chinese wisteria, and Wisteria floribunda or Japanese wisteria. The Chinese wisteria is the more popular plant due to its flowering habit. It grows to a height of 25 feet or more and has flower clusters six inches to a foot in length; flowers open before the foliage has expanded. Individual flowers in the clusters open all at once for a very showy display. Flowers are violet-blue and slightly fragrant. Plants are most showy from early to mid-May in most seasons. There is also a white flowering form of Chinese wisteria, W. sinensis ‘Alba,’ which is very fragrant. Chinese wisteria may bloom within three to four years after planting; however, the juvenile period may be much longer.
Japanese wisteria grows to a height of 25 feet or more and has violet-blue, fragrant flowers that bloom as the foliage is also expanding. Individual flowers open gradually from the base of the cluster to the tip. Clusters can be 12 to 18 inches in length and are effective in late May in most seasons. The plant has yellow fall foliage color. There are numerous cultivars of Japanese wisteria with various flower colors.
- Grow Westeria in fertile, moist but well-drained soil.
- Wisteria will grow in partial shade, but it probably won’t flower. Sun is a requirement.
- If your soil is in poor condition, add compost; otherwise, wisteria will grow in most soils.
- Plant in the spring or fall.
- Choose a site that will not overwhelm nearby plants as wisteria grows quickly and can overtake other plants.
- Each spring, apply a layer of compost under the plant and a 2-inch layer of mulch to retain moisture and control weeds.
- Some gardeners swear by phosphorus to aide flowering. Scratch a couple of cups of bone meal into the soil in the spring and then add some rock phosphate in the fall.
- Only water in the summer if rainfall is less than 1 inch per year.
- Pruning is the secret to good flowering.
- Prune wisteria in late winter. Remove at least half of the prior year’s growth, leaving just a few buds per stem.
- If you want a more formal appearance, prune again during summer after traditional flowering.
- For more blooms, try cutting back the rampant shoots every two weeks during the summer.
- Do you have a new wisteria? Cut the vine back severely right after planting. Then, the next year, cut the main stem or stems back to 3 feet of the previous season’s growth. Once the framework is full size, shorten further extension growth in midsummer to where growth began for that season.
- Informally grown, mature plants need little or no subsequent pruning.
- For a formally trained plant, cut side shoots back to 6 inches in summer, then shorten them again in winter to 3 buds.
- Wisteria will resprout with vigor if cut back severely, but this pruning should be avoided, if possible, because new shoots may take some years before they flower.
- Dieback, crown gall, leaf spots, virus diseases, Japanese beetle, aphids, leaf miners, scale insects, and mealy bugs can all be problems.
Botanical name: Wisteria
USDA Hardiness Zones: 4 to 9
Sun exposure: Full Sun to Partial Sun
Flower color: Red, Blue, Purple, White
Bloom time: Typically early May