Marginal pond plant
Blue flag iris
Iris versicolor L.
A rhizomatous, clump-forming marginal iris suited to pond edges and bog gardens, Iris versicolor is a hardy, full-sun perennial that dies back in winter and is propagated by division.
PLANT PROFILE
About Blue flag iris
Blue flag iris (Iris versicolor) is described in RHS guidance as an aquatic/bog herbaceous perennial suited to pond edges and bog gardens. It grows from rhizomes in clumps and is typically used as a marginal/emergent plant at the water’s edge rather than as a submerged oxygenator. RHS size information lists the species in the 50–100 cm height range (with an alternative single-line description noting growth to 80 cm) and a maximum spread reported as 10–50 cm.
Cultivation notes from the supplied sources recommend planting in moist to wet, deep, humus-rich acid or neutral soil in a sunny position; the species is given a hardiness rating of H7 on the RHS scale. The allowed sources do not provide species-level numeric planting-depth (cm) or a water-depth range (cm) for I. versicolor, so specific centimetre values for planting or standing-water depth are not available from the research provided. Propagation is by division, recommended from mid-summer to early autumn, and the plant is deciduous, with foliage dying back over winter.
Routine maintenance is straightforward in a suitable wet site: no pruning is required, but dead foliage and spent flower stems can be removed after flowering if desired. RHS pest and disease notes list slugs and snails, thrips and potential issues such as aphid-borne viruses, bacterial soft rot and grey moulds. General pond guidance from RHS and Freshwater Habitats Trust suggests containing vigorous pond perennials (for example by planting in baskets or using root barriers) if management is required, particularly in small or confined ponds. The supplied GOV.UK guidance and RHS/Freshwater Habitats Trust pages searched do not identify statutory restrictions specific to Iris versicolor in England and Wales.
POND SUITABILITY