At DeepRoot, we promote large volumes of non-compacted, biologically active loam as essential for street tree health and longevity. Urban foresters generally adhere to the following minimums: 300 cubic feet for small trees, 600 cubic feet for medium trees, and 1,000 cubic feet for large trees. However, some municipalities are taking soil volume cubic feet into their own hands, over 37 to be exact. They are rethinking the vital role trees play in the health of our planet and population. The comprehensive list below includes whether the soil volume is a requirement, recommendation, or a mandate in cities and states in across the US and Canada.
In the table below, you can organize the information by different criteria such as city, state/province, country, and soil volume. Be sure to find the language and read more about the cities decision within it’s associated link.
| Country | State/Province | City or County | Soil volume minimum | Mandated language | Official Documentation | Notes | Last amendment |
|---|---|---|---|---|---|---|---|
| Canada | Alberta | Edmonton | Small tree: 11m3 Large tree: 11m3 | Required | Design and Construction Landscaping | June, 2017 | |
| Canada | British Columbia | Kelowna | 4m3 | Required | City of Kelowna Design Standards | See setion 6B page 8 of 9 | 2012 |
| Canada | British Columbia | Victoria | 12m3 | Required | City of Victoria Subdivision and Development Bylaw | See section 1.2.6., page 6. | 2012 |
| Canada | British Columbia | Vancouver | 0.3 m3 or 0.6 m3 (preferred) | Suggested | Urban Forest Climate Adaptation | See section 4.2, page 41 | May, 2017 |
| Canada | British Columbia | Surrey | small: 15m3 (10m3 shared) medium: 20m3 (15m3 shared) large: 30m3 (20m3 shared) | Recommended | City of Surrey Shade Tree Management Plan | See page 29 | 2016 |
| US | California | Emeryville | small:600 ft3 medium: 900 ft3 large:1200 ft3 | Required | Climate Resilient Street Trees | See download in link for street tree species that are climate resilient (2016) | 2020 |
| US | California | San Diego | Small: 600 ft3 Medium: 1,000 ft3 Large: 1,500 ft3 | Required | County of San Diego BMP Design Manual | See section K, page 31 | January, 2019 |
| US | Colorado | Aspen | Small: 240 ft3 Medium: 600 ft3 Large: 1200 ft3 | Required | Water Efficient Landscaping Standards | See section 4.1 Soil Criteria and Appendix F (tree soil information chart) | January, 2019 |
| US | Colorado | Denver | 750ft3 to 1000ft3 per tree | Required | City and County of Denver Ultra-Urban Green Infrastructure Guidelines | See section 8 | 2016 |
| US | Florida | Pompano Bech | Small: 450ft3 medium: 820ft3 Large: 1280ft3 | Required | Pompano Beach Zoning Code | See section J, 3 language and ratio graph | 2020 |
| US | Florida | Small: 10 ft2 Medium: 20 ft2 Large: 30ft2 | Suggested | Urban Design for a Wind Resistant Urban Forest | See chart on page 4 | February, 2017 | |
| US | Georgia | Decatur | Very small:108 ft3 Small: 300 ft3 Medium: 675 ft3 Large: 1,200 ft3 | Required | City of Decatur Tree Canopy Conservance Ordinance | See page 12 | May, 2014 |
| US | Georgia | Athens-Clarke County | Small: 200 ft3 Medium: 450ft3 Large: 800 ft3 | Suggested | Best Management Practices for Commmunity Trees | See Page 12. more on Athens-Clarke County: https://www.athensclarkecounty.com/273/Tree-Ordinance | 2005 |
| Canada | Ontario | Guelph | Small: 18m3 Medium: 36 m3 | Guidelines | Streescape Manual | See page 56 | 2017 |
| US | Idaho | Boise | 500m3 | Requirement | DOWNTOWN BOISE STREETSCAPE STANDARDS & SPECIFICATIONS MANUAL | See page 26. Section 3: Suspended Paving Systems | 2016 |
| US | Illinois | Chicago | Depth of 3ft of soil. 24 ft2 surface area | Requirement | Chicago Landscape Ordinance | See page 41 | 2000 |
| US | Minnesota | Small: 400ft3 Medium: 800ft3 Large: 1,200ft3 | Guidelines | Minnesotra B3 Guidelines: New Buildings and Major Renovations Version 3.2 | See page 49, Guideline S.4: Vegetation | Jan, 2020 | |
| US | North Carolina | Charlotte | 274ft2 for sidewalk trees 200ft2 for parking lot trees Assuming 3’ of soil depth we can say 822 cf for sidewalk trees and 600 cf of soil for parking lot tree | Required | Charlotte Approved Tree Ordinance | See page 17, Section 2196 2 (parking areas) b-2 | September, 2010 |
| US | North Carolina | Durham | Small: 150 ft2 Medium: 250ft2 Large: 350ft2 | Required | Landscape Manual for Duaham, NC | See page 39, See page 41-106 for type of tree and designated volume | April, 2013 |
| US | North Carolina | Raleigh | 600ft3 | Required | North Carolina Street Design Manual | see page 56, Section 6.18.1 and 6.18.2 | January, 2014 (however link says 2017 in the website link) |
| US | New York | New York City | 1.6- 2.0 ft3/ft2 | Guidelines | NYC Design Guidelines | See page 153, Section 7 | 2010 |
| US | Ohio | Cleveland | Small: 300 ft3 Medium: 600 ft3 Large: 1000f t3 | Suggested | Cleveland Guide for Species Selection | see page 2, Section A | August, 2015 |
| US | Ohio | Columbus | 1000 ft3 (single) 750 ft3 (shared) | Standard | Downtown Streetscape Standards | Select PDF, see page 37, section 5.6 | October, 2015 |
| Canada | Ontario | Guelph | Small: 18m3 Medium: 36 m3 Large: 50m3 | Guidelines | CIty of Guelph Downtown Streetscape Manual & Built Form Standards | See page 56 under Tree Planting | January, 2014 |
| Canada | Ontario | Markham | Small: 15 m3 Medium: 23m3 Large: 30 m3 | Guidelines | Markham Streetscape Manual: Trees for Tomorrow | see page 14, spatial requirements in design guidelines | January, 2009 |
| Canada | Ontario | Kitchener | Small:17m3 (single ) 11m3(shared) Medium: 28m3(single) 18.5m3(shared) Large: 45m3(single) 30m3(shared) | Required | Development Manual | see page 3 of Appendix B | 2015 |
| Canada | Ontario | Oakville | 30m3 (single) 15 m3 (shared) | Recommended | Oakville Forest Management Plan | see page iii, and Appendix C | September, 2012 |
| Canada | Ontario | Toronto | 530 ft3 | Required | Toronto Green Standard V3 | See Ecology Section 1.1. Tree Planting and Soil Volume | May, 2018 |
| Canada | Ontario | York Region | Recommended | Sustainability Performance of New Development York Region | July, 2013 | ||
| US | Oregon | Tigard | 400ft3 to 1,000 ft3 | Required | Urban Forestry Manual | See page 12-1, Section 12 | May, 2019 |
| US | Virginia | Alexandria | 450 ft3 | Required | 2019 Landscape Guidelines | See page 36 | February, 2019 |
| US | Virginia | Fairfax County | 700 ft3 (single) 1200 ft3 (double) | Required | Fairfax County Land Development | See page 12-40 | 2018 |
| US | Washington D.C. | Small: 600 ft3 Medium: 1,000 ft3 Large: 1,500 ft3 | Required | Green Infrastructure Design Standards | See page D-23, See section 47.7. | 2016-07-01 00:00:00 | |
| US | Washington | Bellevue | Small: 500 ft3 Medium: 1000 ft3 Large: 1500 ft3 | Required | https://bellevuewa.gov/sites/default/files/media/pdf_document/2020/2020-environmental-best-mgmt-practices-manual.pdf | See page 81, chapter 8 | 2020 |
| US | Washington | Seattle | 1200ft3 per tree | Guidelines | https://streetsillustrated.seattle.gov/design-standards/street-trees/ | see design guide, at the bottom of the page | June, 2017 |
| US | Washington | Tacoma | Small: 72 ft3 Medium: 120 ft3 Large: 180 ft3 | Required | https://cms.cityoftacoma.org/surfacewater/UrbanForestManual/UrbanForestManual_Volume3.pdf | table on page 16 | 2020 |
| US | West Virginia | Small tree: 500 ft3 Medium tree: 750 ft3 Large tree: 970 ft3 | Required | West Virginia Department of Environmental Protection recommended | See page 7, table | 2008 |
Right now, this list only contains cities in North America – there are no soil volumes for trees that we know of in the United Kingdom – though we hope that will change.
Setting soil volume minimums for street trees tacitly enforces the message that business as usual as far as tree planting is concerned isn’t good enough. We need to continue rethinking how we plan for our urban forests and the role of green infrastructure in the built environment.
Take a look to see if your city, state, province, or, county has been added! Should your city or town be on this list, or do you know of any others that we missed? We want to hear about your goals for growing healthy trees in your community. Please email us at [email protected].
Header image credit: carlos aranda.
This is not research based information. It is people who copied other peoples work who go it from Cornell irrigation work. In other words the soil volume info only applies to Cornell and other similar places that do not irrigate trees
Hi John, I’m not sure I understand your comment. Which information is not research-based? This is simply a list of all the places that we’re aware of that have implemented soil volume minimums for street trees (defined as trees in the public right of way). Are you saying that tree growth/health is not tied to their access to lightly compacted quality soil?
Here in Wales, at Wrexham County Borough Council, i have managed to put in place a Local Planning Policy which states “Where tree planting is proposed within hard surfaced areas (e.g. parking areas and footpaths) the size of the planting pits should be sufficient to provide an adequate volume of soil to support the eventual size of the the planted tree(s)”. Unfortunately, when this policy was adopted i didn’t have sufficient knowledge to stipulate volumes that we would require, however ever since i have been asking for a minimum of 25 metres cubed of good quality planting soil for large growing trees, 15 for medium sized trees and 8 metres cubed for small growing trees, with these figures being reduced by a third for shared pits. When we come to revise our local planning note on trees & development, i will be putting in these requirments.
With regards to CU soil i have been asking for four times the above sizes, as CU soil contains 80% stone therefore the rooting volumes jhave to increase in order to provide the same amount of soil.
Its amazing the number of landscape architects and developers that have been actively fighting this policy as they do not want to spend money. Traditionally in Britain, the vast majority of developers have viewed landscaping as something that municipal planning forces on them and they spend as little on the hole as they try to do with the trees to be planted. The old adage of spend a £100 on the hole and £10 on the tree seems to have been forgotten by so many in this industry. Its such a shame that a huge percentage of the landscape architects over here in Britian do not keep up with continual professional development and still believe that a large tree will survive in a hole with 1 metre cubed of soil. In the past here, a large number of trees were planted in concrete rings in hard surfaced areas, which you would be lucky to get 0.5 metres cubed of soil in, these are what i call concrete tree coffins, and any tree planted in a hard surfaced area which does not provide sufficient volume of soil is a tree coffin.
The lack of understanding of the basic requirements of trees i.e sufficient rooting volume of decent soil by a hell of a lot of landscape architects over here in Blighty is so depressing. Thus having minimum rooting volume policies is such a good idea. I applaud Deeproot for highlighting who actually has policy on rooting volumes for trees. Lets hope more get this type of policy adopted in their municipalities.
Moray, thank you so much for commenting. It’s a slog trying to educate and get everyone on the same page about this fundamental truth: trees need soil. Even if you weren’t able to specify a soil volume minimum in Wrexham the first time around, you’ve laid some important groundwork for future changes. Hopefully those will happen yet! Thanks for everything you’re doing for trees.
I’m not sure that West Virginia should be included in the list. The EPA guidebook listed on their website is just that – a resource for people interested in reading it. To my knowledge, West Virginia has not truly embraced any recommended minimum soil volume requirements.