Ask Mr. Smarty Plants

We are really hoping you are not using the past tense, as in "I already planted it there, now what do I do?" And we are assuming you are talkng about the non-native plant, either Wisteria sinensis (Chinese Wisteria) or Wisteria Floribunda (Japanese Wisteria). Wisteria frutescens (American wisteria) is a native version, not quite as aggressive as the non-natives, but still a woody plant. It is native to Maryland; Carroll Co. is in USDA Hardiness Zones 6a to 7a and American Wisteria is hardy in Zones 6 to 9. From this Ohio State University website Growing Wisteria, we extracted this information to indicate which plant you probably have in your garden:

"Two species of wisteria are typically grown in home gardens: Wisteria sinensis or Chinese wisteria, and Wisteria floribunda or Japanese wisteria."

The first problem for us is that the Lady Bird Johnson Wildflower Center is committed to the use, protection and propagation of plants native not only to North America but to the area in which they are being grown. The second problem, and this has to do with your septic lines and well, is that they are vigorously growing, woody plants. You don't want any woody plants close to your lateral lines, as in trees and shrubs. They are the ones that send roots out far beyond their driplines, sneaking up on you. But you don't want to leave that area completely bare, because you know it wouldn't stay bare, it would get weedy and unless it was mowed, some of those "weeds" would grow up to be woody plants. We don't know how your lateral lines or well are situated, but you do need to be aware of them when planting in that area. As large and aggressive as wisterias are above the ground, you can bet their roots are equally or even more so. 

If you haven't already planted anything there, our recommendation is to not use woody plants, but native grasses, even wildflowers. The long fibrous roots of grasses and herbaceous flowering plants will help hold the soil, but will not interfere with the underground construction. If you have already planted the wisteria, our recommendation is: LOOK OUT!

From our Native Plant Image Gallery:

Wisteria frutescens

Wisteria frutescens

Wisteria frutescens

Wisteria frutescens