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
1 rating

Friday - April 09, 2010

From: Bucks County, PA
Region: Mid-Atlantic
Topic: Shade Tolerant, Trees
Title: Arborvitae thinning in Bucks County, PA
Answered by: Barbara Medford

QUESTION:

My arborvitae trees are about 11 ft. tall. I had them put in about 3 years ago. They were 8 to 10 ft. when planted. After the first year, I have noticed they are thinning to the point where you can see right through them. What can I do to make them full like they once were, or are they dying? Any help would be much appreciated.

ANSWER:

Bucks County in the southwestern corner of Pennsylvania and USDA Hardiness Zone 6b would seem to be the appropriate place for  Thuja occidentalis (arborvitae) to grow.

However, we picked up some facts that may explain the thinning of your plants; the first was from our webpage on Thuja occidentalis (arborvitae).  That offered the information that in a crowded environment, this tree is slender and not well-branched. In the open, it improves in form and density. This Ohio State University site commented that it prefers a moist, well-drained, loamy soil in full sun, but tolerates soils that are poor, rocky, clay, compacted, dry, and of various pHs extremely well, and is very urban tolerant to heat, drought, humidity, and pollution; however, not tolerant of shady situation. From that same article, we also learned that old foliage from the self-shaded middle of the shrub abscises (sheds) noticeably in Autumn, and falls through the interior of the canopy directly to the ground below.

Our conclusion is that if your arborvitae are not in an open area, with plenty of sun, that is probably causing their decline. They are not likely to be dying, but are not going to prosper as much as you might wish. Some of the openness is no doubt the result of the shedding of the interior branches, caused by the plant's own shade, which you can hardly do anything about. 

Pictures of Thuja occidentalis (arborvitae) from Google

From our Native Plant Image Gallery:


Thuja occidentalis

 

 

 

More Trees Questions

Ecosysystem with pecan at center from Austin
February 21, 2014 - Dear Mr. Smarty Plants, I would like to create a native tree guild around a mature pecan. It shares its space with native shrubs and ephemerals but I would like to add a nitrogen fixing plant. I am...
view the full question and answer

Will a gift yucca survive in Northwest Arkansas?
June 28, 2011 - Had received a yucca tree as a gift and wondering if it will survive in the ground here in northwest Arkansas. It has a complete tropical look compared to my regular yucca plants. I believe it's actu...
view the full question and answer

Are blue spruce (Picea pungens) poisonous?
May 30, 2009 - Are blue spruce trees poisonous at all? Thank you.
view the full question and answer

Need to replace a Silver Maple in Illinois.
July 10, 2011 - My father recently had a tornado take out a 50 year old silver maple. He is looking to replace it, but he is looking for something with interesting summer color; as he put it not "green." I am try...
view the full question and answer

Watering live oak trees from McAllen TX
December 24, 2012 - What are the watering requirements for live oak trees in deep south Texas? How often and how many inches to be applied? One pop-up spray sprinkler spaced approximately fifteen feet away from each tr...
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 | STAFF
© 2015 Lady Bird Johnson Wildflower Center