Hello! I have a perennial garden with black-eyed susans that I’m now finding have spread out of control; I’ve just spent 6 tedious hours on this glorious Canada Day picking the little ones out of my sedum, which they seem to be killing. So I intend to dig the plants out — they’re too much work — but am looking for suggestions for replacements — I have a full sun south-facing (East York) garden, love the yellow-orange flowers, but the susans are just too much work. Nothing invasive. What about yarrow, or tickseed/coreopsis? Suggestions welcome! And thank you very much in advance for your help and Happy Canada Day!
How appropriate it is to be thinking of native plants for your perennial garden on Canada Day. Coreopsis, a native North American, is a good option for you. It blooms earlier in the season than the native black eyed susan (Rudbeckia Hirta L.) but if you cut it back, it will flower again in the fall. It is not as prolific a self-seeder as the black-eyed susan. Yarrow, Achillea millefolium is also a North American native, and very lovely, however it too can reproduce aggressively both from rhizomes and seed dispersal and you may find yourself pulling small plants that are not where you want them, or dividing clumps that have got too big.
Some gardeners like to leave at least a few of their black-eyed Susans in the garden because of their cheerful and reliable fall colour. They are considered a biennial or short-lived perennial, but as your experience shows, they spread well by seed. The trick is to deadhead them both to encourage repeat blooming and to discourage seed production.
Here is a link that might give you some other ideas for your garden: The Best Native Plants for Toronto Gardens: https://www.toronto.ca/legdocs/mmis/2018/pe/bgrd/backgroundfile-113557.pdf