Wednesday, April 2, 2008
More Wisteria Information:
Here is one woman's bad experience and an explanation of why this has happened:
"About 15 years ago, I bought two wisteria, placing them alongside a large two-story outbuilding. Big mistake. What I've found out about wisteria is that it seems the more you prune it, the more it finds other ways to spread. It sent roots underground around and underneath the shed and also worked its branches under clapboards and through the walls. The other day I saw it coming out at the eaves on the opposite end of the 20-foot long building. One of the wisteria was moved to a far-off location away from the house to see if it would grow along a large stone wall. It did. It not only took over the wall, but is now growing underground in directions out from the wall. To make matters worse, neither plant has ever produced the lovely purple flower clusters I had originally planted them for!"
When a wisteria is planted near something, like a shed or a wall, it becomes aggressive and invasive, but when it is planted in a place where it has nothing to grab onto, it settles in and behaves. Well it still sends out vines after the spring bloom searching for something to grab onto, but if nothing is found, it stays rather compact.
Why is my Wisteria Not Blooming?
The biggest frustration gardeners face when growing wisteria is that plants have a longer than average juvenile period and sometimes fail to bloom as expected. Start with grafted plants or those produced from cuttings rather than those grown from seed. A plant will also fail to bloom if: it does not receive full sunlight; there is excessive vegetative growth that may have been stimulated by excess nitrogen fertilizer; it is pruned heavily in winter and spring, which encourages vigorous, vegetative growth; and/or it is pruned improperly. Also, in severe winters, flower buds may be injured or killed. The following practices may help induce non-blooming vines to flower: a heavy application of superphosphate (0-20-0) in early spring (3#-5# per 100 square feet) severe pruning of new growth in late spring or early summer root pruning in late fall.
Wisteria can be propagated via hardwood cutting, softwood cuttings, or seed. However, seeded specimens can take decades to bloom; for that reason, gardeners usually grow plants that have been started from rooted cuttings or grafted cultivars known to flower well. Another reason for failure to bloom can be excessive fertilizer (particularly nitrogen). Wisteria has nitrogen fixing capability (provided by Rhizobia bacteria in root nodules), and thus mature plants may benefit from added potassium and phosphate, but not nitrogen. Finally, wisteria can be reluctant to bloom because it has not reached maturity. Maturation may require only a few years, as in Kentucky Wisteria, or nearly twenty, as in Chinese Wisteria. Maturation can be forced by physically abusing the main trunk, root pruning, or drought stress.
Although I love the look and smell of the Wisteria vine and flowers, I personally prefer ivy and climbing roses when using a plant on the face of a building.