Japanese iris has three essential requirements: sun, acidic soil, and abundant moisture. It requires no other care beyond picking off Japanese beetles, which have a fondness for the flowers (see page 116). Divide in late August to give the plants a chance to become well established before winter. Protection is necessary for the first winter in northern climates (see page 117).
When it’s in bloom, Japanese iris provides one of the most outstanding floral displays a garden can feature. For hundreds of years, specialists in Japan have been hybridizing this plant to produce some of the largest flowers of any perennial (up to 10 inches across), in shades of lavender, maroon, mauve, pink, purple, and white. One of the delights of Japanese iris is that all the subtle variations in hue are perfectly complementary to each other. The long, swordlike foliage remains attractive even after the flowers fade. This kaempferi is a variegated form.
ZONES: 4–9
BLOOM TIME: Midsummer
LIGHT: Full sun
HEIGHT: 24–48 inches
INTEREST: Huge orchid-like blossoms that float like exotic birds above rich green foliage
Japanese irises thrive in wet soils, so they’re ideal for the edges of ponds and streams. Plant as a delicate accent in a mixed border or in groups by themselves—in a location where you can bask in the full impact of their delightful beauty. Since Japanese irises make astonishing cut flowers, be sure to make room for them in a wet corner of the cutting garden.