As of this summer, Raleigh, NC now requires a minimum of 600 cubic feet of soil for all street trees planted in the right of way for new developments. Their new Street Design Manual outlines this requirement, and the design methods available for achieving it, in section 6.18, page 82-86.
The design standards also specify that soil volumes should be connected wherever possible to increase the overall amount that is available to the roots.
Congratulations to the City of Raleigh for this fantastic policy change. You’re in good company. And special thanks to Sally Thigpen, Assistant Parks Superintendent for the City of Raleigh, for contacting us to let us know.
Top image of a southern magnolia blosson in Raleigh. Flickr credit: bobistraveling