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?


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

Sunday - May 16, 2010

From: Denver, CO
Region: Rocky Mountain
Topic: Poisonous Plants
Title: Is arborvitate (Thuja sp.) safe for horses
Answered by: Nan Hampton


Is arborvitae poisonous to horses? I want to plant it along the horse pasture. If it is poisonous, what are similar plants that are not poisonous to horses?


Neither Thuja plicata (western arborvitae) nor Thuja occidentalis (eastern arborvitae) appear in any of the toxic plant databases listed below:

ASPCA Toxic and Non-Toxic Plant Lists—Horses

Poisonous Plants of North Carolina

Cornell University Plants Poisonous to Livestock

Toxic Plants of Texas 

University of Pennsylvania Poisonous Plants

Canadian Poisonous Plants Information System

This is a pretty good indication that it would be safe to plant in your horse pasture.



More Poisonous Plants Questions

Is cat palm (Chamaedorea cataractarum) poisonous?
March 18, 2009 - I have a Cataractarum (Cat) Palm and am wondering if it is poisonous. I have a Cockatiel who likes to play in it. Thank you!
view the full question and answer

Herbal properties of Dicentra formosa
January 23, 2016 - I would like to get some information on the Dicentra formosa plant such as the benefits of the plant. Is it poisonous? Can it be infused in an oil?
view the full question and answer

Are dogwood trees poisonous to horses?
April 26, 2009 - Are dogwood trees poisonous to horses?
view the full question and answer

Plants to replace poison ivy in Kingsport TN
July 03, 2009 - Am in the process of killing off poison ivy that is growing vigorously. What do you recommend to plant in its place. I don't want to leave area open to other invasive plants. (Yes, poison ivy is a...
view the full question and answer

Is wild foxglove poisonous to dogs from Liberty TX
May 05, 2012 - Is penstemon cobaea (wild foxglove)poisonous to pets, specifically dogs. I was thinking about adding this to my native Texan wild flower section of my backyard.
view the full question and answer

Support the Wildflower Center by Donating Online or Becoming a Member today.
© 2016 Lady Bird Johnson Wildflower Center