Bluejoint is found on moist forest sites and along stream banks. It commonly invades clearcuts and a wide variety of disturbed soils, but is most aggressive in wet soils, or deep, fine soils capable of holding moisture. Bluejoint is a significant competitor with young seedlings. Root competition dominates as bluejoint produces a dense, continuous sod. It also shades and smothers seedlings.
Conifer seeds fall on grass above soil and sprouting seeds dry and wither as the grass dries out.
Bluejoint grows best in full sunlight, on moist, nutrient-rich sites. It is rare to absent under a closed forest canopy, but clones that are present and that survive a disturbance that removes the overstory will rapidly expand by rhizome growth. As vigor increases, so does seed production. Wind dispersal of seeds is important. Wetlands may serve as seed sources in areas of predominantly old forests.