Iris Care, Planting, and Maintenance

When to plant

Iris are dormant right after they bloom and remain dormant for about a month. (If you are separating your iris, dig them up and divide them and plant them right after they finish blooming.) If you ordered Iris, inspect them, dry them for several hours, and plant them. Iris rhizomes are not bulbs; they shouldn’t be left unplanted for more than one day.


Iris do best if the rhizome is pointed North, with the outside of the fan facing South. This gives the fan the most sun exposure.  Trim the leaves into the shape of a fan that comes to a point at the top. (See the illustration for August, next page.) If the leaves are not trimmed, the wind cans up-root the newly planted iris.  

To allow for the spread of the rhizomes, which increase every year, the optimum distance between plants is twenty-four inches.  At a minimum, plants should be at least twelve inches apart. The rhizome is part of the stem and the roots are below the ground.  The rhizome should not be planted deep. The surface of the rhizome should be barely covered with dirt. 


Iris like a neutral soil, { 7 PH limy}.  Bone-meal is a safe dressing when used sparingly.  A good fertilizer is 5-12-12.  Apply fertilizer when bloom stalks appear and mid-summer after bloom.  (A basic rule with Iris is that starvation is better than over feeding.)   Do not use Miracle Grow -- it is too high in nitrogen.  Water every two days until the Iris are established, they begin rooting and start growing.  Once established, water your iris twice a week, allowing the ground to dry between waterings. Be sure not to forget your iris in the winter -- water them at least once every two weeks.  You don’t need to mulch iris; they can withstand the cold.


Trim or remove dead leaves, trim brown tips of leaves, and remove bloom stalks after bloom. You can trim the leaves into pointed fans in late fall.  Remember, the leaves provide the energy for rhizome growth, which ensures good bloom.  Do not compost dead iris leaves or bloom stalks since they can promote disease.

The Iris Plant


Iris Development over time


The Art of Dividing Iris

As iris grow, one plant can turn into many. Over time, they outgrow their space; the rhizomes rise up and appear crowded.  This is the time to divide them.

Dig up the entire plant; wash off the rhizomes and roots with a hose.  Each fan, except for the original rhizome, will have a clearly defined section of rhizome attached.  Break the rhizomes apart, trim the fans, and dip the rhizome in a solution of one part Clorox to ten parts water.  Lay each rhizome (and fan) on the ground to dry out for a day or two or until the part that is broken looks dried out, not an open wound.  Plant rhizomes at least twelve inches apart, following planting instructions.

If the rhizomes have soft spots, cut off the spots before dipping in the Clorox solution.  Remember to discard all cut off parts.

1. Iris rhizome before dividing.

2. Iris rhizome divided.

3. Iris rhizome trimmed and ready to plant.

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