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How to Care for Bearded Iris

Large light purple flowers

Iris plants are generally care-free and dependable bloomers year after year, but there are things you can do to maximize bloom production and keep your plants happy and healthy.

About every three to five years, depending on the variety, rhizomes will need to be thinned out to promote continued maximum bloom production.

General planting and care

  • Plant rhizomes in well-drained soil in a location that gets at least 6 hours of full sun. They should be planted with the top third of the rhizome extending above the soil level.
  • Planting them 12 to 24 inches apart will allow for less frequent thinning.
  • Overwatering is a common mistake. Deep watering at longer intervals is better than more frequent shallow watering, however new plantings will require more frequent watering until established.
  • To promote good flower production, a low nitrogen fertilizer such as a 6-10-10, bone meal, or superphosphates are all effective options. Following manufacturer's directions, apply a light application twice a year, in early spring and again about a month after blooming is over.
  • Keep weeds, fallen tree leaf debris, and grass roots out of the bed to help discourage disease and insect infestation.

Bloom season is over – now what?

  • Remove spent bloom stalks by cutting them off close to the base. This can be done as soon as all blooms on the stalks have withered.
  • Healthy green leaves can be left alone but remove any diseased or browned outer leaves.
  • Trim leaves down to a height of about 6 inches at summer’s end or early fall. This encourages new root and rhizome development and gives the bed a neater appearance over the winter.
  • If necessary, the rhizomes can be covered with straw or a thin layer of soil in the case of a very cold winter weather event, but it should be removed as soon as possible once the threat is over.
  • Observe plants for signs of disease or insect infestation and treat as indicated.

Dividing and Transplanting

This should always be done a minimum of six weeks prior to the first frost. Remove clumps from the ground using a shovel, taking care not to damage the roots. The center rhizome from which others have grown eventually dies and does not rebloom, so it should be removed and discarded. The offshoots that will be replanted should be trimmed to six inches in height. Dig a hole deeper than necessary and create a mound in the center of the hole to place the rhizome on top of. This makes it much easier to spread the roots out in a downward fashion all the way around before covering with soil. Be sure not to plant too deeply, keeping the top of the rhizome exposed to the air.

Firm the soil around the rhizome. Once transplanted, more frequent watering will be necessary. Water initially and then once every seven to ten days until the roots are well established.

Some varieties are re-bloomers and typically bloom again about four to eight weeks after the initial bloom. For these, keep beds clean and wait until after the second bloom to trim foliage or divide and transplant.

With a little extra care, you will be rewarded with an abundance of blooms on your happy, healthy plants!

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