Hi, I am doing some research into the possibility of building an arbour over my driveway and training a wisteria macrostachya (blue moon) to trail over it. I will plant it with compost in a clayish (we live on a delta) soil 4 feet from a house foundation and 1 foot away from a cement driveway. It will get June sun from 8:30am-1:00 pm and 4:00pm – 7:00 pm daily. Our water table is only 5 feet down in summer and can be as high as 2 feet in the winter. My concerns:
#1 that the plant drips sap on cars below the arbour.
#2 that the roots will get into the house foundation or lift the driveway.
I picked an American variety because I thought it less evasive. Should I be concerned about the two points above given my planting coordinates & situation?
Thanks very much for your help,
Hardiness zone 8a
Thanks for contacting the Toronto Master Gardeners with this query. Wisteria macrostachya or Kentucky Wisteria, a North American native, is considered less invasive than its Chinese or Japanese counterparts (Wisteria sinensis, and Wisteria floribunda). To answer your specific questions:
- Wisteria does drip sap, which can stain indelibly by many reports, but this occurs only when it is pruned and stems are cut, which you would need to do regularly to keep the plant in good condition and under control, especially as it matures.
- Wisterias are strong plants both above and below the ground. Once established they are vigorous growers, and they should not be planted too close to house foundations. https://homeguides.sfgate.com/dont-plant-wisteria-close-house-104847.html
Since you are located in British Columbia, you may wish to check more locally for information that is specific to your growing conditions. The UBC Botanical Garden has a useful forum https://forums.botanicalgarden.ubc.ca/ in which gardeners can post their queries.