Bogs and borders of peatlands; moist coniferous forests or swamps, including moist areas in jack pine plains and oak or aspen forests; sometimes in much drier habitats than Kalmia polifolia. Locally abundant and every bit as handsome as K. polifolia when in bloom, but more restricted in range in the state.

Usually reaches the peak of blooming in late June or the first half of July, a full month or more after K. polifolia. The corolla is generally a little smaller than in K. polifolia: less than 12 mm broad, whereas in our K. polifolia it runs 13–20 mm.