Yellow Flag Iris

Plant in full sun or partial shade in wet soil or shallow water up to 15 cm deep at the pond margin. Yellow flag iris is extremely vigorous and spreads by thick rhizomes, so plant it in aquatic baskets to contain its growth in small to medium ponds. In large wildlife ponds and natural waterways, it can be planted directly into the mud. Space plants 60-90 cm apart. It tolerates a wide range of soil types from heavy clay to silt. Water is rarely needed as it grows in permanently wet conditions. Feed is unnecessary in fertile pond mud. Remove spent flower stems after blooming. Thin out congested clumps every three years in early autumn by lifting and dividing the rhizomes. The variegated cultivar 'Variegata' is less vigorous and suited to smaller ponds.

Cut back flower stems after blooming. Remove yellowing or brown foliage in autumn, cutting to just above the waterline. This prevents dead foliage from decomposing in the pond over winter. Leave some upright stems standing for overwintering insects.