How to Grow, Maintain, and Divide Bearded Iris

Bearded iris is among the most elegant -- and easy to grow -- flowers of spring. Follow our tips for long-lasting, ever-multiplying blooms.
Expert Tips
Bed of white bearded iris in a garden A well-kept bed of iris offers
years of beautiful spring flowers.

It's a magical time when bearded irises unfurl their pencil-slim buds to reveal a kaleidoscope of color in spring. Once commonly called flags, these perennials flourish in USDA Zones 3-9, where winter temperatures dip below freezing and allow the plant to go dormant before next year's growth.

"Anyone can grow iris," says Doris Winton, who has had a lifelong attraction to the flower and is a master judge for the American Iris Society. While fragrance has diminished through hybridization, the size of blooms has increased, as has the palette. "Every color -- except fire-engine red -- can be found in bearded iris," Doris says.

Below are Doris's tips for growing outstanding bearded iris.


Iris Growing Tips

Five varieties of bearded iris in vases Some of iris expert Doris Winston's
favorites. See the last page for

  • Plant them in a sunny spot in late summer. The plants need well-drained soil and at least six hours of sunlight per day. A full day of sun is even better to keep the rhizomes dry. (The rhizomes are the fleshy rootlike structures at the base of the plant.)
  • Prepare their beds. Doris recommends a low-nitrogen fertilizer and a soil pH slightly less than 7, which is neutral. She applies a granular fertilizer twice a year -- in early spring and just after bloom when the rhizomes are forming the next year's flowers. Water only if it is extremely dry or after transplanting.
  • Give them room to breathe. Bearded iris require good air circulation. Plant them a minimum of 16 to 18 inches apart (less space for dwarf irises and more for taller varieties).
  • Do not mulch. Mulching retains moisture, and too much moisture will cause soft rot of the rhizomes.
  • Break off seedpods that form after the blooms have faded. This prevents seedlings from choking the surrounding soil. Seed formation also saps energy needed by the rhizomes, roots, and leaves.
  • Prune back the foliage in the fall. This will reduce the chances of overwintering pests and diseases.
  • Make dividing a habit. Divide clumps of bearded iris every three to four years in the late summer. (See the next page for detailed instructions on dividing and replanting bearded iris.)

Continued on page 2:  Dividing Bearded Iris