Hello — I’ve checked all the local nurseries and online, and I can’t find single stem, high branching Jacquemontii birch trees anywhere…except one online store that lists them for $300 each, which is far outside my budget. They are very common in the UK, but here it seems they’re all multi-stem, low branching. If you have any advice on suppliers or nurseries that might have these wonderful trees, I’d appreciate it very, very much!
The Toronto Master Gardeners are unable to recommend specific nurseries, but if you have not already done so, you could broaden your search using the common name Himalayan Birch, or Whitebark Himalayan Birch and you may come up with more local sources for this gorgeous and relatively rare ornamental tree, and perhaps a supplier of a single stem variety. One of the possible issues with general availability is that Betula utilis var. jacquemontii is considered hardy to Zone 6 in Canada, which would make it quite vulnerable to any severe winter temperatures in Toronto, and it is more vulnerable to insect pests and stress in extreme heat and humidity at the other end of the climate spectrum. The Missouri Botanical Gardens website offers a good overview of this tree: https://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?kempercode=e358
However, having said all this, it is certainly one of the loveliest trees of the birch family and I wish you all success in your search.