How to Garden With Bearded Iris

Overview

The bearded iris is among the most popular flowering plants that home gardeners enjoy growing. Their colorful springtime flower has a fuzzy "beard" in the center of each flower petal, and the wide range of colors and heights makes one of the thousands of cultivars appropriate for any garden's color scheme. You can choose from several types of bearded iris, from miniature dwarf to tall varieties that grow over 3 feet tall. Most bearded iris need full sun, but the more delicate, lighter colored irises can tolerate partial shade.

Gardening With Bearded Iris

Step 1

Prepare your planting area in mid summer in a spot that receives the appropriate amount of sunlight for the variety you plan to grow. Combine organic matter such as compost, pine bark and leaf mold with your topsoil at a ratio of about 1 part organic matter to 4 parts soil. Dig it into the soil at least 6 inches deep.

Step 2

Plant bearded iris rhizomes between July and September. Dig a shallow hole with your trowel, and then pile some soil in the area where you will be planting each rhizome, enabling the rhizome to sit slightly above the top of the soil. Spread the roots, if there are any, all around the mound you built, and then fill the hole with additional soil. Water your newly planted bearded iris well by running a sprinkler in the area for at least 30 minutes. As your bearded iris grows, keep the soil moist, but avoid keeping it soggy or waterlogged, because this can cause the rhizomes to rot.

Step 3

Fertilize your bearded iris with a low nitrogen plant food having an N-P-K ratio of 5-10-10 when you plant it. Use about ½ pound of this type of fertilizer for every 50 feet of row. Reduce the amount to 1.5 oz. for every 10 feet of row if your area is smaller. After this time, fertilize each clump with ½ cup of 5-10-10 plant food after the irises finish flowering for the season.

Step 4

Spread a layer of mulch over the ground around your iris to protect the rhizomes from cold winter temperatures. Remove the mulch in spring.

Step 5

Cut spent flower stalks and foliage to within 6 or 8 inches of the ground in late summer or fall.

Step 6

Divide your bearded iris every three to five years four to six weeks after blooming is complete. Using your spade, dig up clumps of rhizomes and then wash them with a sharp stream of water. Separate the rhizomes with a sharp knife or clippers, leaving one fan of foliage with a clump of white roots that feel firm. Discard older rhizomes, because they probably will not flower again.

Tips and Warnings

  • North Carolina State University does not recommend the use of animal manure for growing bearded iris unless it is well-composted and you dig it into the soil at least 6 inches deep, ensuring that it does not touch the plant's rhizome.

Things You'll Need

  • Well-drained soil
  • Organic matter
  • Spade
  • Fertilizer
  • Trowel
  • Clippers
  • Knife

References

  • North Carolina State University: Bearded Iris for the Home Landscape
  • Clark University: Irises

Who Can Help

  • American Iris Society
Keywords: bearded iris, flowering plants, bulbs rhizomes

About this Author

Barbara Fahs lives on Hawaii island, where she has created Hi'iaka's Healing Herb Garden. Fahs wrote "Super Simple Guide to Creating Hawaiian Gardens," and has been a professional writer since 1984. She contributes to Big Island Weekly, Ke Ola magazine, GardenGuides and eHow. She earned her B.A. at UCSB and her M.A. from San Jose State University.