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?


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
Not Yet Rated

Wednesday - January 18, 2012

From: Folsom, CA
Region: California
Topic: Planting, Shrubs, Trees
Title: Need tree suggestions for a long, narrow strip in Folsom, CA.
Answered by: Jimmy Mills


I live in Folsom, Ca. I have a long strip (50') of planting area about 2.5' wide at the top of a retaining wall to the fence behind it. I would like to plant alternating (2) trees down this strip to block views of neighbors yards (maybe 12'-15' high). Can you tell me two types of trees that won't send roots through the fence or retaining wall?


Mr. Smarty Plants is having some difficulty visualizing the situation that you describe. How tall is the fence, and what type is it? It sounds as if you are hoping to the constrain the tree roots in a 2.5' wide space along the length of the wall. This is referred to by some people as a non-invasive root system. 
People frequently ask about “taproot” trees thinking that the root grows straight down and will not interfere with sidewalks, driveways, and foundations. Some trees begin with a taproot, but as the system matures, it spread out in all directions in search of water and nutrients, and to provide a base of support to stabilize the tree. A tree that reaches a height of 20 feet can have a canopy at least that wide, and will have roots that spread out three to four times the width of the canopy. I am including links to Colorado State University Extension and Iowa State University Extension that explain this concept further.

As for the tree recommendations, I am going to introduce you to our Native Plant Database that will help you select trees for your situation. The Database  contains 7,161 plants that are searchable by scientific name or common name.

 There are several ways to use the Database, but we are going to start with the Recommended Species List.  To do this, go to the Native Plant Data Base and scroll down to the Recommended Species List box. Clicking on the map will enlarge it so that you can click on Northern California. This will bring up a list of 286 commercially available native plant species suitable for planned landscapes in California. These aren’t all trees, so you need to go to the “Narrow Your Search” box on the right  of the screen and make the following selections: select California under State, Tree under General Appearance, and Perennial under Lifespan. Check Sun under Light Requirement, and Dry under Soil Moisture (or the conditions that apply). Click on the Submit Narrow Your Search button and you will get a list of 13 native species from which to chose.  Since trees may not be appropriate for your situation, you can go through the selections again, this time choosing Shrub under General Appearance. Click on the Narrow Your Search button, and now you have 32 native species. Clicking the Scientific name of each plant will bring up its NPIN page that gives the characteristics of the plant, its growth requirements, and in most cases, photos. You can get different lists by changing the Light requirement and Soil moisture selections.

Here is another link to Colorado State University Extension that has good information on tree selection.

For help closer to home, you might contact the folks at  the Sacramento County office of University of California  Cooperative Extension.



More Trees Questions

Control of Juniperus ashei
August 08, 2007 - We have just purchased 2 acres in Burnet County at an elevation of 1604 feet above sea level. The land is almost flat, bedrock, with lots of Juniper, Cactus Apple and between these plants grasses and...
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

What is meant when Mimosa Tree is described as an invasive tree in San Antonio TX?
May 14, 2013 - When it is stated that the Mimosa Tree is invasive, does that mean that the Roots are invasive or does it mean that the seed pods will drop and make many more trees ?
view the full question and answer

Seedlings of elm trees in Illinois
June 09, 2008 - I have what I believe to be young elm trees sprouting throughout my front yard. I will pull them up and over night more sprout and will be 5+ inches tall. I would like to know how to get rid of them, ...
view the full question and answer

Fertilizing oaks to produce more acorns
March 04, 2009 - What type of fertilizer would I use on oak trees to possibly increase growth and acorn production ? I have some flooded oak timber that is home to migrating ducks but there is little for them to eat.
view the full question and answer

Support the Wildflower Center by Donating Online or Becoming a Member today.
© 2015 Lady Bird Johnson Wildflower Center