How to Prune sweet flag?
Cut back after flowering

sweet flag · Acorus calamus
Also known as: beewort; calamus; cinnamon sedge; flagroot; myrtle flag; myrtle grass; myrtle sedge; sea sedge; sedge grass; sweet calamus; sweet myrtle; sweet sedge; water iris
Grow at pond margins in very moist or wet soils in full sun. Grows best in water no deeper than 22cm. Divide every few years to prevent congestion, See bog gardening, pond plants and Ornamental grasses cultivation
Cut back after flowering