Calamagrostis canadensis aka Bluejoint

Calamagrostis canadensis is a perennial grass in the Poaceae family. Gardeners also know it as bluejoint or blue-joint grass. Its native range runs from subarctic North America into the United States. It is native to the Midwest as well. In northern North America, it grows in marshes and swamps. It also grows along river margins. These habitats help explain its preference for moist growing sites. It is not native to Britain or Ireland.

This upright grass forms clumps and grows very fast. In gardens, it can reach 6 feet (1.83 metres) tall. Its width can reach 2 feet (0.61 metres). The tall, narrow form gives plantings a strong upright shape. Bright green leaves make up the leafy part of the clump. Bluejoint is a cool-season grass. Its flower heads rise above the leaves and catch the light. The flowers add a different texture to the green growth.

Chicago Botanic Garden describes the flowers as reddish brown. Its bloom colour listings also include red and purple. The garden's account places flowering in late spring and early summer. Its separate bloom listings cover May through August. Taken together, these records suggest a broad flowering window. The flower heads are a key part of its garden appeal. Large groups make their form and movement easier to see.

Bluejoint prefers moist soil and full sun to partial shade. Chicago Botanic Garden also lists full shade among its exposures. It describes the grass as tolerant of a wide range of conditions. The account notes a preference for moist, brackish soils. Under favourable conditions, this fast-growing grass can become aggressive. Its spread deserves thought when choosing a place in a border. The garden lists it for USDA hardiness zones 3–9.

Mass planting suits this grass and shows off its upright form. It can also serve in borders or as a screen. Chicago Botanic Garden lists it for bedding and hedge use. The plant can remain standing to give winter interest. Cut back the old growth in late winter. Clumps can also be divided at that time when needed. Its strong growth and potential aggression matter when planning these uses.