is it too late in the season to sow coneflowers seed in ground now.. Boston MA area.
It will take about 3 months for coneflowers sewn now to have 2-3 sets of leaves. This means they will be young plants going into winter. The answer to your question depends on the severity of your winters. Mother nature sows seed in the fall for early spring germination when the soil is moist and temps cooler. Hot weather is not good for seed germination or survival of seedlings despite best efforts to keep the soil moist. If your winters are mild and frost free until Nov/Dec, sow seeds indoors now and transplant when temps are cooler. Don't forget to acclimate the plants to outdoor conditions first. Or sow seed in late fall where you want it to grow next spring. More growing info here: https://www.gardeningknowhow.com/ornamental/flowers/coneflower/growing-purple-coneflowers.htm