Answer: In my experience it can take several years for a seedling mimosa tree to attain sufficient maturity to begin blooming well. In a cold climate such as yours where the growing season is shorter and the winter cold stress is more severe, it may take a bit longer. I should mention that although mimosa treess are winter hardy into zone 6, your zip code places you in zone 7, but your tree might be in a cold spot. This might keep it from blooming after especially cold winters. Aside from lots of sunshine and withholding fertilizer, there's not much you can do to encourage flowering except to wait for your tree to mature a bit more. Best wishes with your mimosa.
Q&A Library Searching Tips