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Q. Who is Mr. Smarty Plants?

A: There are those who suspect Wildflower Center volunteers are the culpable and capable culprits. Yet, others think staff members play some, albeit small, role. You can torture us with your plant questions, but we will never reveal the Green Guru's secret identity.

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Ask Mr. Smarty Plants is a free service provided by the staff and volunteers at the Lady Bird Johnson Wildflower Center.

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Sunday - November 22, 2015

From: Bakersfield, CA
Region: California
Topic: Non-Natives
Title: Containing Japanese Wisteria Roots
Answered by: Anne Van Nest

QUESTION:

I have some Japanese wisteria plants that I would like to plant inside root barriers but I cannot find any info on how deep the roots go. Do you know if a 2 ft deep root barrier for trees can contain wisteria roots?

ANSWER:

Francesco Vignoli on his Wisteria website has this to say about the roots: The wisteria roots spread so strongly and abundantly that if planted near walls or pavements they can easily grow into them causing serious damage. To prevent this from happening it is advised, whilst planting, to insert a corrugated plastic panel which will force the roots to take other directions, as they are unable to pass through it. Place the plastic panel (at least 2m long) 80cm deep, between the plant and the wall or pavement (or the surface to be protected). In the case of walls and pavements made with cement this problem does not exist.

He recommends a barrier that is almost 3 feet deep on his Wisteria website.

Also, Barbara Medford has answered a question about planting non-native wisteria near a well or septic system (a similar situation) that you might want to read. Her answer is found here.

 

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