Yellow flag iris, Iris pseudacorus, is a vigorous water iris, typically found growing at the edges of large, sunny ponds. It spreads by rhizomes and bears large clumps of green leaves from which elegant, yellow flowers appear in late-spring.
Iris pseudacorus is ideal for wildlife gardens, and looks particularly good if planted in naturalised drifts among other moisture-loving plants. It also associates well with dark blue flowered plants. If you don't have room for a pond or bog garden, try growing it in a large container filled with water. Divide clumps every three to five years to keep it under control.
Iris pseudacorus 'Variegata' is a charming variegated form. The variegation lasts during spring only, with the cream-yellow and green-striped markings fading by summer, in time for the beautiful yellow flowers to have their moment. Iris pseudacorus 'Variegata' is less vigorous than the species, making it a good choice for smaller ponds. The Royal Horticultural Society has given it its prestigious Award of Garden Merit.
For best results, grow in boggy soil or on a pond shelf to 15cm below water level.
A note on toxicity: irises are toxic to pets, but the toxicity is considered mild and non life-threatening. If your pet consumes a large amount of foliage or the rhizome, seek veterinary advice.