A friend of mind is experimenting with native plants in her perennial beds and is doing research on how well they perform as host plants for caterpillars and as nectar and pollen sources for pollinators. She claims that the hands-down winner in her garden is Common Mountain Mint (Pycnanthemum virginianum), a beautifully scented native with delicate blooms that is an attractive garden specimen in its own right.
My personal favourite is Golden Alexanders (Zizia aurea), a plant that I became aware of after seeing it in her garden. It’s attractive and is a host plant for black swallowtail butterflies – what’s not to love?
Eryngium has a lot of drawing power for pollinators. Although not native to Ontario, I can vouch for Eryngium agavifolium, also known as Agave-leaved Sea Holly. I worked at Lost Horizons last summer and it was by far the most popular plant in the nursery for bumblebees. It is also a very striking architectural plant for design purposes, though a bit spiky to handle. A close second were some vibrant rose-coloured nativars of Wild Bergamot (Monarda fistulosa); bumblebees would invariably cling and hitch a ride rather than abandon ship when customers brought pots to the cash counter.
Check out more examples of native plants for the garden in this great article by Benjamin Vogt: