Plant of the week: Dwarf bearded iris

Plant pots of these charming early-flowering varieties now

Mention bearded iris and most people think of those flamboyant tri-cornered blooms held aloft on stiff, ramrod stems in May. Often overlooked are the dwarf kinds, which are no less dramatic, but produce their multi-coloured fleur-de-lis flowers earlier in April, on 18-40cm (7in-1¼ft) stems, allowing the blooms to hover just above or among a clutch of pointed blue-green leaves.

Known as standard dwarf bearded iris, they’re a recent creation, first appearing in the USA in the late 1950s. Geddes Douglas of Tennessee posted pollen of his tall bearded varieties to Paul Cook of Indiana, 500 miles away; he grew dwarf species I. pumila, and in turn returned the favour. The resulting offspring of different heights were selected and named, with their original ‘Green Spot’ and ‘Lilli-white’ varieties still available. Older varieties tend to have drooping fall petals, while in modern hybrids the trend is for horizontal fall petals, which gives them more presence in the garden. They can be grown with other creeping perennial and alpine plants that like full sun, such as thyme, Phlox douglasii, Geranium sanguineum and Veronica repens.

Dwarf bearded iris need the same conditions of moist, well-drained soil and full sun, with rhizomes exposed so they ripen in the summer sun to stimulate blooms for spring. They need an open site not shaded or swamped by expansive perennials. Like their larger cousins, they can be lifted every three to four years in July, and divided, planting only the youngest rhizomes, each complete with a fan of leaves,

leaving the surface of the rhizome open to the sun.