Yellow flag (Iris pseudacorus and cvs.) EYE-riss soo-DAY-kor-us Genus:  Iris Yellow flag is a vigorous Laevigata iris with ribbed, sword-shaped gray-green leaves. It grows to 3 to 4 feet high. Over 60 cultivars exist, including ‘Beuron’, with evenly yellow flowers; ‘Ecru’, with its off-white blooms; ‘Fresh Cream’, with lovely, pale-yellow flowers marked with red-violet signals; a variegated type, ‘Variegata’; ‘Donau’, a bright-yellow flower adorned with a brown signal that looks like stitchery; and nearly sterile ‘Holden Clough’, with deep-yellow blooms and reddish purple veining. Noteworthy Characteristics:  Extremely adaptable. Self-seeds freely along streambanks and edges of ponds. Flourishes in both shallow and deeper waters. Care:  Grow in full sun to part shade and most any moist soil. Cut flower spikes at the end of the growing season to prevent excessive self-seeding. Sterile cultivars exist. Propagation:  Lift and divide clumps, or separate bulb offsets, and plant immediately, in early autumn. Problems:  Iris borer, verbena bud moth, whiteflies, iris weevil, thrips, slugs and snails, aphids, and nematodes.

Overview

Height 3 ft. to 6 ft. Growth Pace Fast Grower, Invasive/Aggressive Grower Light Full Sun to Part Shade Moisture Adaptable Maintenance Moderate Characteristics Self Seeds, Showy Flowers Bloom Time Summer Flower Color Yellow Uses Beds and Borders, Cut Flower, Waterside Style Water Garden Seasonal Interest Summer Interest Type Perennials