En EspaŅol

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
Can't find the answer in our existing FAQs, submit a question to Mr. Smarty Plants.
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

Trees poisonous to horses from Landrum SC
April 15, 2012 - Please tell me if the following trees are poisonous to horses: hickory, beech, poplar, and redbud. Thank you very much.
view the full question and answer

Possibility of saving hurricane-damaged Umbrella Magnolia
October 12, 2005 - Our beautiful umbrella magnolia Magnoliaceae Magnolia tripetala was toppled during Hurricane Katrina. We have lifted it back in place, however it looks very distressed. I have the following questions:...
view the full question and answer

Time to trim oak trees in Austin
October 29, 2011 - We have several large oak trees in desperate need of a good trimming. Given that the trees have had a very stressful drought year, when would be the best time to trim them?
view the full question and answer

Is post oak resistant to oak wilt from Dallas TX
November 22, 2013 - I am confused. The NPIN website says that Post Oak IS susceptible to oak wilt, but all the other information I have been able to find says that it is resistant to oak wilt and rarely gets the diesase....
view the full question and answer

Pecan trees too close together in Austin
August 14, 2012 - There are two pecan trees in my central Austin yard. Each is four or five inches diameter at chest height and maybe 15 feet tall. They are within six feet of each other and their canopies interfere wi...
view the full question and answer

Smarty Plants's Facebook profile Support the Wildflower Center by Donating Online or Becoming a Member today.

Mr. Smarty Plants wants you to be his Facebook friend. Click the Facebook icon to add yourself to Mr. Smarty Plants list of friends.
E-NEWSLETTER | BECOME A MEMBER | DONATE NOW | MEDIA | SITEMAP
© 2014 Lady Bird Johnson Wildflower Center