I was going to compile a list, then I heard Ontario Native Plant Gardening has one. To access it join the Facebook group, and then check out this pdf. It’s one of many files available to members and is the most extensive list of Ontario growers I have seen. We Seed Change also has a long list of local seed providers here, but not necessarily exclusively native plants. (For the whole of North America, check out North American Native Plant Society’s list.) If you’re an Ontarian serious about turning your property into a natural oasis, please join ONPG if you’re on Facebook. You will learn tons. I am learning tons. There are groups like that springing up for various states and provinces, so no matter where you are you’re likely to be able to find one from your growing region.
For Ontario, I hear good things about Grow Wild in Omemee, Ecology Park in Peterborough, and Wildflower Farm in Coldwater. And Ontario Native Plants. In memory, I have mostly used ONplants.ca (my fav!), Richter’s Herbs (carries native and nonnative), a tree nursery in Quebec (carries native and nonnative) – all of which I’ve been happy with. And our local native plant sale in Haliburton. Otherwise, friends have given me plants and seeds. Never underestimate asking your friends for plants, divisions, cuttings or seeds. You may get too many plants. Is there such a thing?
And for plant and landscaping ideas, I recommend this book for Canadians (fyi like most of our book links, it’s an affiliate link):
If you have a favorite supplier, please comment! Drop their links!