August 3, 2022:

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I wish developers would plant semi-mature trees more often than these silly little saplings which look half dead.

A few things on this:

1) Survival rates for larger trees are lower. This is because their roots have to be cut way back to move them and they have a much larger body/organism to support.

2) Larger trees are way more expensive. The typical street tree planted is described for most people's purposes as 6-10ft tall (industry publications will use different measures). They cost $250-500 installed depending on the species.
The next size up tends to run about $1,000 installed. Much larger than that and the trees are increasingly hard to source, and often have to be taken from the wild or someone's yard rather than a nursery, and the cost can be
as much as $20,000 installed for 30ft-40ft tree depending on species.

3) Larger trees require significantly larger planting areas if they are to succeed.

4) Larger trees require much higher volumes of water to survive in their first 2 years, which almost certainly necessitates irrigation and a lot of it!

For street trees, going one size up to say 500cm trees ~16ft is plausible, but only for open trench planting, and only with very large cubic volumes of soil (over 40m3) and irrigation

I would tend to avoid anything larger as a risk-reward thing, unless you're planting in super high quality space.

Toronto has gotten better in recent years with requirements of silva cells and higher soil volumes, but we're still not at a level that will typically support the biggest trees, as street trees, in most settings.

One has to also keep in mind, it's comparatively easy to design the right conditions into completely new communities/neighbourhoods etc, but much harder next to a built-up streetscape where better conditions for the trees have to compete with underground utilities and sidewalk width.
 
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