Botanical name: Wisteria
Plant type: Shrub
Bloom time: Spring
If your garden is an outdoor room, wisteria provides the drapery and slipcover—to camouflage a view or provide living shade over porch and pergola. Something between a vine and a shrub, wisteria blooms vigorously in spring with showy, cascading flower clusters that provide quick-growing color.
However, note that it can take a good six years for a newly established wisteria to start flowering—sometimes longer!
The vine may grow 10 feet or more in one year! This gives the artful gardener a paintbrush with which to cover the landscape-canvas. Wisteria is also beautifully fragrant providing a feast for the senses.
Note: Some types of wisteria are considered invasive pests; check with your local cooperative extension. All parts of this plant, especially the seeds, are poisonous.
- Grow in fertile, moist but well-drained soil.
- Ensure placement has full Sun. Though wisteria will grow in partial shade, it probably won't flower. Sun is essential.
- If your soil is in poor condition, add compost; otherwise, wisteria will grow in most soils.
- Plant in the spring or fall.
- Dig a hole as deep as the root ball and 2 to 3 times as wide. Space plants 10 to 15 feet apart.
- 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 pring 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 mealybugs can be problems.
W. floribunda (Zones 5 to 9) of Japanese origin, is capable of growing 30 to 60 feet (and beyond in the South).
- 'Honbeni' (syn. 'Honko') is one of our favorites, bearing clusters of pink flowers in late spring.
- 'Alba' (syn. 'Shiro Noda') bears lovely clusters of pure-white clusters; it blooms in late spring.
W. macrostachya (Zones 4 to 9) or Kentucky wistera is a late-season bloomer. It climbs to about 25 feet.
- 'Blue Moon' is an extra-hardy wisteria with silvery-blue clusters and blooms in late spring and often again in the summer.
Wit & Wisdom
Wisteria still not blooming? Some readers have sworn by this method: Take a shovel and drive it eight to ten inches into the ground about a foot and a half out from the trunk to slice into some of the roots. Damage about 1/2 of the roots and the bush will be shocked into reproduction. It is very difficult to hurt this rampantly-growing, unrestrained, often invasive plant.
Send this e-card of a wonderful wisteria!