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
1 rating

Friday - September 26, 2008

From: Aledo, TX
Region: Southwest
Topic: Trees
Title: Distance from wall to plant Eastern red cedar
Answered by: Nan Hampton


I want to plant a row of Eastern red cedar on the high side of a 2 to 2 1/2 ft large Pavestone block retaining wall, preferably as close to the wall as possible. We have put maybe 4-5" of gravel behind this wall to facilitate drainage, and this should deter root growth toward the wall. How close to the wall can I safely plant these trees? Thank you much.


Juniperus virginiana (eastern redcedar) generally grows to around 40 feet high, but can grow as tall as 90 feet. Its width at maturity can be 8 to 20 feet wide.  How close to your pavestone wall you choose to plant should be guided by the range of any lateral roots and width of the mature tree.

The US Forest Service database says:  

"Eastern redcedar generally has a shallow, fibrous root system, though roots of mature eastern redcedar trees may penetrate 25 feet (7.6 m) and lateral roots may reach 20 feet (6 m).  Eastern redcedar seedlings have penetrating taproots and may later develop a lateral taproot system.  The deep, early taproot is usually replaced by an extensive, shallow root system with age.  Even 1st year seedlings begin developing a long fibrous root system, often at the expense of top growth.  The root system may be deep where soil permits, but on shallow and rocky soils eastern redcedar roots are very fibrous and tend to spread widely.  The development of a lateral taproot with age may also enable eastern redcedar to persist on outcrops and shallow soils."

The US Forest Service Silvics Manual says that the soil condition determines whether the tree develops a deep tap root or spreading lateral roots.  In thin rocky soil fibrous lateral roots will be predominant; but, if the soil permits, the root system may be a deep penetrating tap root.  So, if your soil is good, you shouldn't have great concern about lateral roots.  

You should probably not plant the trees a distance from your wall that is less than half the width of the mature tree.   Kansas Forest Service recommends a planting spacing for redcedars of 6 to 10 feet and University of Missouri Extension recommends a spacing of 8-12 feet.

Cultivars have been developed that are smaller; for instance, according to the University of Connecticut there is a cultivar, 'Emerald Sentinel', that is a pyramidal, columnar shape that grows to 20 feet high and only 8 feet wide. If this tree sounds as if it is tall enough for you, it could probably be planted 3 to 4 feet from your wall.

Juniperus virginiana

Juniperus virginiana

Juniperus virginiana

Juniperus virginiana




More Trees Questions

Is it normal for the bark to fall off an oak tree in Austin, TX
May 02, 2013 - Is it normal for live oak bark to fall off when touched? I am afraid to get near them?
view the full question and answer

Need to know how to plant trees to create a windbreak in Ashburn, VA.
May 06, 2010 - I want to know how to plant trees to create windbreaks. I live on a slope of a hill, the front of the house is steep and the back of the house has neighbors in a cul de sac. I swear I live in a wind...
view the full question and answer

Sticky stuff dripping from non-native crape myrtle in Austin
August 01, 2012 - There is sticky sap-like stuff dropping from the very large crepe myrtle in my yard. The tree has quit blooming. This didn't happen last year when it was so dry; it started after we had all the rain ...
view the full question and answer

Tan, rough, fan-shaped growth on mountain laurels
July 01, 2014 - A tan rough fan-shaped "something" is growing at the end of the mountain laurel branch where the flowers would be .. what is it and can it harm the plant?
view the full question and answer

Selecting a tree for a backyard in San Antonio, TX
May 11, 2013 - Hello Mr. Smarty Plants, I recently moved into a home in West San Antonio right outside Loop 1604..my treeless backyard is fairly small at about 55 ft long and 15 ft wide. I am torn because I can't ...
view the full question and answer

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