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When to prune hardy wisteria? #765110

Asked August 01, 2021, 8:06 PM EDT

Hello there! I am hoping to learn a little bit about a wisteria. First I am curious as to what variety it could be. I have seen "Blue Moon" and "Summer Cascade" as possible options. Secondly, I have seen information that recommends pruning twice a year, once in late summer and once in late winter. Could you direct me toward some information about pruning wisterias that are cold-hardy? Thank you

Hennepin County Minnesota

Expert Response

Wisteria vines bloom best in full sun. Apply a thick mulch around the root zone in winter to protect roots in exposed locations or colder microclimates. Wisteria are aggressive growers that develops a heavy wood structure. Supports such as a fence, arbor or trellis must be able to accommodate that weight. They are aggressive plants so it’s advised to not plant them too near to your home. In late winter, prune the long shoots that have grown since the summer pruning down to three to five buds. Prune back any stems that show signs of winter die-back. Prune the long shoots of the current year’s growth back to 6 inches long in early summer after the vines have flowered. Also at this time, completely remove any shoots not needed for the main framework of the plant and prune away root suckers. Failure of vines to produce flowers may be attributable to a number of causes including death of flower buds in winter, too much shade, plants too young (especially seed grown ones), improper pruning or overfertilization.

https://www.finegardening.com/article/pruning-and-training-wisteria

https://growingtogetherwithdonkinzler.wordpress.com/2017/05/16/new-winter-hardy-wisteria-vine-for-northern-climates/

https://www.startribune.com/how-to-prune-wisteria/16543176/

Summer Cascade™ wisteria American wisteria (Wisteria frutescens), is hardy to zone 3. Flower are dark lavender 10-12 inch bloom clusters . Vines grow 15-25 feet long.

Blue Moon Kentucky Wisteria has lavender blue flowers and is hardy to zone 4

http://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?taxonid=265854

https://mnhardy.umn.edu/varieties/woody-ornamentals/wisteria

It is best to avoid  the following wisteria

Two studies in the southeastern U.S. found 82-96% of wisteria collections were hybrids of W.

sinensis and W. floribunda (W. x formosa).

Other names for Japanese Wisteria, Wisteria floribunda include:

  • Common names: fuji; Noda-fuji; Chinese wisteria
  • Scientific names: Kraunhia floribunda, Rehsonia floribunda, Glycine floribunda

Other names for Chinese wisteria, Wisteria Sinensis include:

  • Scientific names: Rehsonia floribunda

https://dnr.wisconsin.gov/topic/Invasives/fact/Wisteria.html

Pat M MN master gardener and TCA Replied August 01, 2021, 10:30 PM EDT

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