How to Plant and Grow Irises

Planting iris in the fall yields flowers next spring

Planting iris in the fall yields gorgeous blossoms next spring. Nothing beats iris for sheer beauty and presence in the garden. The luscious flowers, some with subtle fragrance, come in a multitude of colors. Planting iris is one of the easiest fall gardening chores and a half hour of work now will mean weeks of enjoying your iris next spring.


With over 300 species of iris found on nearly ever continent in the world, it's no wonder this popular perennial tops the list of gardeners' favorite flowers. When referring to planting iris, most gardeners refer to the German bearded iris, the flowers commonly seen blooming throughout the United States starting as early as May in most climate zones. Other varieties frequently planted include dwarf types, which tend to bloom earlier, and Japanese iris.

Most iris are sold as bagged rhizomes. Rhizomes are the fleshy parts of the root, similar to a potato. Bagged iris typically contains the rhizome with a few roots hanging off it and sometimes a little green tip. Plant rhizomes as soon as you can in the garden. Sometimes garden centers offer already started iris in pots. If you're fortunate enough to find these, they are planted just like any other perennial. Plant iris in the fall to encourage spring blooms next year.

Planting Iris

Planting iris is easy, and beginning gardeners can successfully grow iris with minimal fuss.

Site Selection

Iris need full sun, at least six hours or more daily. They aren't too fussy about soil, but most types don't like to have their feet wet, so be sure to choose well-drained areas in the garden. If the soil contains a great deal of clay or is slow to drain, amend it well with compost or other organic matter. When choosing an area of the garden to plant iris, be sure to select a location with plenty of room around the iris for it to grow and spread. Iris grow to be about two to three feet tall, and will spread through the years into the garden through the root system, putting up new plants through vegetative propagation. Leave a space of at least one foot around the iris to allow room for growth. Later, as your iris gets bigger, you can divide the iris and move the offspring to other parts of the garden or give away plants to friends, family and neighbors.

How to Plant Iris

After selecting the site, use a good bone meal-based fertilizer or a low nitrogen fertilizer, and work it into the soil according to package directions. Nitrogen is the first number in the three numbers on a bag of fertilizer, so look for one that has a low first number. If possible, incorporate fertilizer and soil amendments a few weeks before you intend to plant iris to allow time for it to spread into the soil.Begin planting iris by digging a shallow trench just deep enough to plant the rhizome. Rhizomes are planted long side against the ground, with the little bulb-like stem of the plant facing up. Don't plant the rhizome too deeply, or it may rot. Simply place the rhizome into the trench, spread the roots out along the soil, and place soil over the roots. Tamp the soil down firmly with your hand or spade to ensure the rhizome stays in place.

When planting iris of more than one color, plant similar colors together for a soothing effect, or use contrasting colors for drama. Always face iris the same way if planting more than one iris, and be sure to leave one to two feet of space between them.

You may want to include a garden marker to remember where you've planted the rhizome. Garden markers can be as elaborate as copper or plastic markers purchased at the garden store, or you can make markers at home from old popsicle sticks. Plant markers are especially helpful with flowers like iris when you want to plant annuals in the spring. They help you remember where you planted iris rhizomes, tulip bulbs, daffodils and similar flowers.

Iris Care

In the spring, you'll begin to see iris shoots. The hallmark sword-shaped leaves emerge next. Iris flowers appear in late spring, unfurling along a single stem. Once the flowers are finished, let the foliage remain so that the plant can continue to develop a strong root system and flowers for next year. By the third or fourth year, your iris bed may get crowded as the happy iris send up new plants. Iris may be divided in late summer.

Iris Resources

  • Visit the American Iris Society for cultural information, breathtaking photo galleries, and answers to all questions pertaining to planting iris.
  • The Gardener's Network includes information on varieties, propagation and more.
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How to Plant and Grow Irises