Wisteria winter kill

Asked June 12, 2015, 1:33 AM EDT

I live in Ottawa, Canada and have a wisteria blue moon which has died back to the ground each year. Last year after several years it sent up 5 or 6 shoots that grew more than 8 ft but again died back to the ground. It has never bloomed. I pulled it out this year thinking that maybe the grafted top has died and now the root stock is sending up shoots from the ground. However I just read an answer from one of your experts that wisteria plants are not grafted but grown from seed. Some articles state that they are usually grafted and some say they are grown from seed...which is correct? I would very much like to know as I have replaced it with a new American wisteria,summer Cascade Betty Mathews. How can I protect it from winter damage? Also I would like to know if a wisteria would ever bloom if it continues to die back to the ground every winter. I live in most likely a zone 4 area just on the outskirts of Ottawa which is a zone 5.

Outside United States

1 Response

Dear Gardener,

Many wisterias are said to be hardy, but those that bloom on old growth may have their buds damaged by frost in spring. The plant named 'First Editions Summer Cascade' is said to bloom on new growth, unlike most others that bloom only on older (or very old) growth. This should give you a better chance at seeing it bloom once it gets established.

There seem to be differences of opinion on the classification of wisteria, and the labeling is only as reliable as the grower. A variety developed by the University of Minnesota for northern climates is known as Wisteria macrostachya 'Betty Matthews'. It seems that this variety may have been developed from a sport which occurred in the namesake's garden. Most cultivated wisteria are taken from cuttings, layering or grafts and bloom within 3 or 4 years. (Seed-raised plants can take up to 20 years to bloom.) Grafted plants have a visible bulge at the graft union above the crown.

This may not help you identify your cultivar, but I do hope yours truly blooms on new wood. You should have a good chance if you give it a site with full sun, good drainage, and protection from wind if possible. Prune it only after the bloom or you will lose the flowers that year.