O give me space, lots of space, and no wires up above
Don’t fence me in
Let me root through the wide open soil that I love
Don’t fence me in

photo: William Fountain, University of Kentucky, Bugwood.org
photo: William Fountain, University of Kentucky, Bugwood.org

Apologies to Cole Porter, but his original cowboy song brings to this arborist’s mind what just might be the pine-ing of tree roots wishing for more space to grow.

Communities seeking to build sustainable urban forests are finding better ways to plant and grow healthy trees, including creating tree-friendly planting sites by setting soil volume requirements. Found on the blog site, DeepRoot, is a list of municipalities that have taken action to make sure trees have the space they need to grow by “redefining requirements for green utilities, specifically for trees, soil and stormwater management…”

Several of these innovative sites are listed below. Follow this link, for more examples of soil volume policies. Perhaps you’ll grow some innovative ideas of your own, like these cities have:

  • Toronto’s Green Development Standard – The City of Toronto calls for street trees to get a minimum of 15 m³ (529 ft³)of high quality soil per tree if in a shared planter, and a minimum volume of 30 m³ (1,059 ft³) of soil per tree if in a single planter.
  • Baltimore Waterfront Healthy Harbor Initiative – This initiative sets an example for increasing the tree canopy as a way to preserve the environment and manage stormwater. Using permeable paving, landscaping, rain gardens, and green roofs, it asks for sites to filter more than 50 percent of stormwater runoff from areas and install at least 1,500 cubic feet of soil for tree pits using structural soils or suspended pavement for any new impervious surfaces or retrofit/redevelopment projects.
  • Denver Parks and Recreation Forestry Department – The city’s “Street Tree Plan Review Checklist” sets a soil volume minimum of 750 cubic feet of soil per tree and states that, “5’ x 5’ pit areas shall no longer be accepted, must use trenches, root paths, break out zones, structural cells, or other un-compacted soil technology.”
  • Emeryville, California – The community requires minimum rootable soil volumes for new trees planted in the public right of way by private developers. The minimum is based on the size of the tree at maturity: 600 cubic feet for a small tree, 900 for a medium tree and 1200 for a large tree.
edgewood pear - fall
This small pear has enough rooting area, but may hinder visibility at this intersection. Be sure that the site where you plant will provide enough room for the healthy, long-term growth of a tree. photo: DNR