[CANUFNET] Looking for hard surface planting experiences/successes

[Naomi Zurcher]

Hi Astrid:

An adequate accessible soil volume is a challenge for Urban Forests globally and I have had tremendous success with CU Structural Soil, both in new installations as well as retrofits - replacing existing pavement where trees are already in place.

What is critical with CU Soil or other structural soil recipes is to use it as it was designed - to replace the soil substrate under paving that must be compacted to an engineering load bearing spec. Structural soil was never designed to serve as the planting medium as it does not encourage good structural root growth over the long term and installations that have ignored this and used structural soil as the planting medium as well as under paving have seen their maturing trees fall over.

I saw Rhoda’s post as to another recipe which may or not be an equal competitor to the well researched CU Soil. Critical is the sizing of the stone - no fines!!! And that the soil is a clay loam for the water holding content and the ability to form aggregates. Last is the importance of the small amount of hydrogel additive. Since the matrix is easily disturbed, either as a result of delivery or just transfer from the mixing area to the installation, hydrogel is essential to retain the soil within the stone voids. No hydrogel and the soil has a tendency to drop out of the voices.

Once you expand accessible soil volume and consider combining with alternative paving layout and permeable / porous or pervious paving strategies, you can grow Platanus x hybrida without the conflicts.

Wishing you success with your initiative
Naomi


Arbor Aegis
Urban Forester / Consulting Arborist / I-Tree team affiliate member
6006 Luzern
Switzerland


> On Oct 4, 2023, at 4:39 PM, Astrid Nielsen via CANUFNET <canufnet at list.web.net> wrote:
> 
> Dear urban forestry colleagues,
> 
> We are working on a project with our local Business Improvement Association in Ottawa to examine the barriers around successful hard surface tree establishment along our main street, and how to overcome them. We have completed a cursory literature review, but with limited data, I am reaching out to the UF community with hopes that some of you will be willing to share your anecdotal experiences on what you feel are the best ways to plant trees successfully in hard surfaces. We recognize that soil volume is a significant barrier, and will be making recommendations to increase this, where possible, and incorporate the use of soil cells, if feasible. For situations where this is not an option, what are the next best alternatives? 
> 
> If any of you have experience in your areas with hard surface planting, I would appreciate learning from you! 
> 
> Please feel free to contact me directly if you prefer: astrid.nielsen at dendronforestry.ca <mailto:astrid.nielsen at dendronforestry.ca>
> 
> Thank you,
> 
> Astrid
> ___________________________________
> Astrid Nielsen, MFC
> Ontario Registered Professional Forester
> ISA Certified Arborist®
> ISA Tree Risk Assessment Qualified
> 
> astrid.nielsen at dendron <mailto:astrid.nielsen at dendronforestry.ca>forestry.ca <mailto:astrid.nielsen at dendronforestry.ca>
> +1.613.805.WOOD (9663)
> 
> www.dendronforestry.ca <http://www.dendronforestry.ca/>
> 

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