En Español

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.

Help us grow by giving to the Plant Database Fund or by becoming a member

Did you know you can access the Native Plant Information Network with your web-enabled smartphone?

Share

Ask Mr. Smarty Plants

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

Search Smarty Plants
    
 
See a list of all Smarty Plants questions

Please forgive us, but Mr. Smarty Plants has been overwhelmed by a flood of mail and must take a break for awhile to catch up. We hope to be accepting new questions again soon. Thank you!

Need help with plant identification, visit the plant identification page.

 
rate this answer
Not Yet Rated

Wednesday - July 22, 2009

From: Harrisville, MI
Region: Midwest
Topic: Trees
Title: Planting under Walnut Trees in Harrisville, MI.
Answered by: Anne Bossart

QUESTION:

I have 2 50+ yr old Black Walnut trees in Northern Michigan (zone 4). I am planting a new bed (raised of course) and was considering adding a hydrangea. I am curious if this will thrive due to the juglone caused by Black Walnut or if I should be ok. Some sites say YES and some say NO.

ANSWER:

You didn't mention if you are building a raised bed in the root zone of the walnut nor how deep it is.  Most of a tree's feeder roots (which need water, nutrients and air) are in the top 36 inches of the soil, no matter how big the tree is.  So any time you change the existing grade and cover those roots with soil, you are putting the tree in jeapordy.

You also didn't mention what type of hydrangea you are planning to plant ...and hydrangeas don't appear to be juglone tolerant.  Some native shrubs suitable to your area that are juglone tolerant include:

Amelanchier arborea (common serviceberry)

Hamamelis virginiana (American witchhazel)

Hypericum prolificum (shrubby St. Johnswort)

Physocarpus opulifolius (common ninebark)

Rhus aromatica (fragrant sumac)

However, from personal experience (I have a property at approximately the same latitide as you, on the eastern shore of Lake Huron, in Ontario) I have found that many things grow under my two very huge old (one is over 100 years old) walnut trees that should not.  I wonder if the soil conditions this far north have a diminishing effect on juglone.  So if you are planning to plant a hydrangea that is native to Michigan and suited to the garden conditions and plant community existing on your property, it is probably worth a try.

 


Amelanchier arborea

Hamamelis virginiana

Hypericum prolificum

Physocarpus opulifolius

Rhus aromatica

 

 


 

More Trees Questions

Plants for full-sun landscape
November 20, 2007 - I live in a very rocky area just outside of Fort Worth, TX. It's taken me all spring, summer & now I'm going into the fall, to landscape just 30 feet in front of my house. The front of the house get...
view the full question and answer

Impenetrable privacy hedge in Wimberly, TX.
July 26, 2011 - I live near Wimberly, TX. I'd like to grow an impenetrable privacy hedge about 200' long and at least 10' tall and 10' deep (or more) using native plants. I'd like it to be evergreen, drought t...
view the full question and answer

Pecan tree dropping limbs in Grand Prairie, TX.
September 04, 2012 - Our 15 year old pecan tree is losing it's limbs. The tree and its leaves look healthy with no signs of bugs or mites, but all the limbs are drooping and breaking off. The tree did have a bumper crop ...
view the full question and answer

Hybrid Leyland Cypress leaning in Annapolis MC
June 29, 2011 - We have a large, 9-year old Leyland Cypress that has tipped over. It is still green and growing but leaning slightly off center. It's about 20' tall. Should we stake it? If so, we'd like to do ...
view the full question and answer

Failure to thrive of newly planted magnolia in Irving TX
November 10, 2009 - I planted four Little Gem Magnolia (Magnolia Grandiflora) in my back yard during first week of October 2009. One of them seem to be dying because its leaves have turned very brown and the leaves are c...
view the full question and answer

Support the Wildflower Center by Donating Online or Becoming a Member today.
E-NEWSLETTER | BECOME A MEMBER | DONATE NOW | MEDIA | JOBS | SITEMAP | STAFF INTRANET
© 2016 Lady Bird Johnson Wildflower Center