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 - 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

Growing Green milkweed vine from seed
July 29, 2015 - I was given some seed for the pearl milkweed vine which I intend to plant, but I can find no information on whether to stratify or scarify them or just plant them. I know some milkweeds require strati...
view the full question and answer

Shade tolerant plants for Waynesville MO
April 09, 2013 - We moved to Waynesville, MO (gardening region 6) and when we bought our house there was a nice looking gardening area in front of the house. It is shaded moderately by a Redwood Tree and was "occupie...
view the full question and answer

Low maintenance, shade tolerant groundcover for Pacific Northwest
August 09, 2012 - What's a good low maintenance, shade tolerant ground cover for the Pacific Northwest? It needs to have good erosion control, too.
view the full question and answer

Plants for shade, poor soil in Park Ridge NJ
June 17, 2010 - Hello! I live in far northeast New Jersey, by the New York state border. I am looking for plants for areas of my lawn that nothing currently grows in - due to shade and poor soil quality - very rocky,...
view the full question and answer

Ornamental grasses under desert willows from Dallas, TX
September 06, 2013 - I am planning on planting 3 desert willows in full sun, below the power lines at the back of my back yard in the White Rock Lake area of Dallas. I would like to plant some ornamental grasses in the be...
view the full question and answer

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