Host an Event Volunteer Join Tickets

Your gift keeps resources like this database thriving!

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

Wednesday - March 18, 2009

From: Portland, OR
Region: Northwest
Topic: Shade Tolerant
Title: Shade tree for Portland, OR
Answered by: Barbara Medford

QUESTION:

Looking for shade tree for Portland, Oregon, with non-invasive root system. House will be 20 ft away, with basement.

ANSWER:

We wish we knew how to explain to a tree that it should not invade foundations, buckle sidewalks or pop roots up in the garden, but that's just the way trees are. Most of their roots are within 6 to 12 inches from the soil surface, and they are relentless in their search for water, oxygen and nutrients. The following is an extract from a previous Mr. Smarty Plants question:

"As to the exact distance either should be planted from foundations or sidewalks, that becomes a matter of personal judgment. Soil subsidence around foundations is more often the result of the soil becoming too dry. It is true that tree roots will range out from their trunk as much as twice the diameter of the tree crown in search of moisture but this is usually not a prime factor in foundation damage. 

In general terms regarding the planting of trees near structures, the ground area at the outside edge of the canopy, referred to as the dripline, is especially important. The tree obtains most of its surface water here, and conducts an important exchange of air and other gases. The most critical area lies within 6 to 10 feet of the trunk. Paving should be kept out of the dripline and no closer than 15 feet from the tree trunk."

With that in mind, we are going to look at Recommended Species in our Native Plant Database, and find smaller trees that will result in less extensive roots but still give some nice shade to the area. Also be aware, as noted above, of the damage roots can do to sidewalks and drives in their area. These trees will all be native not only to North America but to Oregon. Native plants grown in their natural habitat will require less water, food and maintenance.

TREES FOR OREGON

Juniperus scopulorum (Rocky Mountain juniper)

Pinus contorta (lodgepole pine)

Prunus virginiana (chokecherry)

Umbellularia californica (California laurel)


Juniperus scopulorum

Pinus contorta

Prunus virginiana

Umbellularia californica

 

 

 

 

 

 

More Shade Tolerant Questions

Plants for wildlife and trees for shade.
September 29, 2007 - We live in Kempner Texas, our land has mostly cedar trees. We would like to make a wildlife habitat on the back side of our property. Can you recommend plants that will grow in shade to partial sun,...
view the full question and answer

Deer-resistant plants for under cedar and oak trees in Austin
June 22, 2010 - I have about 1.5 acres in southern Travis county. It's full of mature live oaks and cedar trees, and the soil is full of limestone. I've been gathering the limestone and using them to create raise...
view the full question and answer

Plant for deep shade in Pennsylvania
April 09, 2013 - Hi! I am landscaping our house and trying to use only plants that provide seasonal benefit to bees, butterflies, birds etc. not the deer though. My question is that I have a fairly steep slope of abou...
view the full question and answer

Shade tree with no roots to interfere with patio in Lake City FL
April 24, 2011 - I have a 4x4 area surrounded by cement patio but would like a tree for shade that does not have roots that will mess up the slab.
view the full question and answer

Erosion control for shady slope in Kentucky backyard
August 28, 2013 - I live in northern Kentucky (near Cincinnati). I have an area in my backyard that has slope. It is next to an ash tree and is very shady. Water erosion has washed away the top soil and pretty much no...
view the full question and answer

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