Contact Us Host an Event Volunteer Join

Support the plant database you love!

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

Growing non-native avocado outside from Austin
December 27, 2012 - My son has a very large avocado tree that he rooted from a pit that is currently growing in a large container. However, it has gotten too big to winter inside. Can it be planted in the ground in Aust...
view the full question and answer

Are the moths in my Austin, TX live oaks harmful?
November 03, 2009 - It is November and my live oak trees are full of moths. What are they and are they harmful to my trees?
view the full question and answer

Young oak tree with dead branches
April 10, 2009 - I purchased my home new a year ago and we have three young oak trees that came with the house. Two of the trees are doing great and their new leaves have grown in. One tree however still has dead le...
view the full question and answer

Desert Willow and Orchid tree with no upper leaves from Kerrville TX
May 30, 2013 - I have two 5 year old Desert Willows planted in my yard. This year only one has leaved out and blooming. The other is bare but the branches are not dead and it has new growth at the bottom. Do you kno...
view the full question and answer

Failure of flameleaf sumacs to produce fruit
January 09, 2013 - Our two flame leaf sumacs produce none to little fruit. Both are about 4 years old, quite large, healthy looking; flowering this year was very good, but no fruit. What keeps them from producing fruit?
view the full question and answer

Support the Wildflower Center by Donating Online or Becoming a Member today.