Rent Shop Volunteer Join

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

Sticky stuff dripping from non-native crape myrtle in Austin
August 01, 2012 - There is sticky sap-like stuff dropping from the very large crepe myrtle in my yard. The tree has quit blooming. This didn't happen last year when it was so dry; it started after we had all the rain ...
view the full question and answer

Native replacement for bamboo from Houston
May 21, 2013 - I've read one reply where you do not advise using Bamboo as a privacy fence plant. What do you suggest in its place? The suggestions on the one I read will not work for me. Your suggestions were My...
view the full question and answer

Problems with Texas Ash in Cibolo TX
May 14, 2010 - I have a Texas Ash tree I planted two years ago. The tree was 10 feet high with thick foliage. This spring the leaves started falling off after I spread fertilizer on my yard. The end of the branches ...
view the full question and answer

Selection of trees for new home
June 30, 2008 - We are moving to Roanoke, Texas(Denton County) into a new home. Our home will have 3 trees which we can choose. They are Texas Ash, Live Oak, Sweetgum, Silver Leak maple, Cedar Elm and Bradford Pear...
view the full question and answer

Tree for memorial in Levittown NY
August 09, 2010 - I am planning a tree planting memorial in Wantagh Park and I don't know what will be hardy enough to grow there. There are the constant breeze and salt water elements to deal with there and of course...
view the full question and answer

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