How to Grow Bearded Irises

Steve Bender
Bearded Iris
Jim McKinley/Getty Images

Few perennials match the amazing show, sweet fragrance, wide variety, and easy care of bearded irises. They come in just about every flower color, both solids and bicolors. Branched flower stalks range in height from 8-inch miniatures to 48-inch giants. Some selections rebloom in fall. All make excellent cut flowers. Provide full sun and well-drained soil. Feed in spring and early summer with Espoma Bulb-tone 3-5-3. Don't plant too deeply; the top half-inch of the thick roots, called rhizomes, should be visible from above. A great source with lots of choices is schreinersgardens.com.

Soil
Bearded irises need good drainage. They’ll grow in soils from sandy to claylike—but in clay soils, plant in raised beds or on ridges to assure good drainage, avoid rhizome rot.

Planting
Plant in September or October, in full sun or light shade. Space rhizomes 1–2 ft. apart; set with tops barely beneath soil surface, spreading roots well. Growth proceeds from the leafy end of rhizome, so point that end in direction you want growth initially to occur. For a quick show, plant three rhizomes 1 ft. apart—two with growing ends pointing outward, the third aimed to grow into the space between them. On slopes, set rhizomes with growing end facing uphill. If weather turns hot, shade newly planted rhizomes to prevent sunscald and possible rot.

Water
Water newly planted rhizomes well to settle soil and start growth. Thereafter, water judiciously until new growth shows plants have rooted; then water regularly until fall rains or frosts arrive. From the time growth starts in late winter or early spring, water regularly until about 6 weeks after flowers fade; buds for next year’s flowers form during postbloom period. During the summer, plants require less water. In heavy soil, it may be sufficient to water plants every other week; in lighter soils, try watering weekly.

Fertilizer
For best performance, feed plants with commercial bulb fertilizer as growth begins in spring, then again after bloom has finished.

Challenges
In cool, moist springs, leaf spot may disfigure foliage; use appropriate fungicide at first sign of infection. Remove old and dry leaves in fall.