Lo, an Iris Reblooming

For many of us, seeing the first Irises bloom in the spring is a thrill. We enjoy the exquisite blooms, often several to a flower stalk. We may even cut off one beautiful one and enjoy it in our dining room in a narrow vase. But alas, in a day or two, the bloom wilts, and the second bud may then open, bloom for a day or two, and fade. Well, there is some good news for us Iris lovers. Reblooming Irises are becoming more and more available. In fact, several varieties were for sale at the Big Country Master Gardener Spring Plant Sale last week. The other good news is that these rebloomers have a great scent.

Reblooming Irises are bearded Irises that bloom in the spring and again in the fall. And if conditions are ideal, they will bloom a third, and even, though rarely, a fourth time in a year. Irises have been around for many years, coming to North America from Europe and the Mediterranean. Their precise origin is not known. The Bearded Iris, or iris germanica, is the one we are most familiar with. This Iris naturalizes quickly and does not need special care, except it does require full sun to bloom well, and every four or so years, it crowds itself and needs to be divided in order to flourish well.

What makes an Iris a rebloomer? The definition has to do with the chromosomal traits that must be present, and the Iris must have the capacity to rebloom in the fall. A reblooming Iris produces an increase (growth of a new section of rhizome) within the year that matures and produces a flower stalk that blooms. The rebloomer does not go through a period of dormancy, but continues to grow during hot weather. 

This reblooming propensity requires that these plants be given some special care. This type of Iris blooms earlier than the standard varieties. It requires some moisture during the winter months while its rhizomes store energy for spring growth. It requires fertilization with very low nitrogen to help with the growth of the roots of the creeping rhizome underground, not its leaves. It also requires full sun (at least 6 hours) for maximum blooms, and good drainage so rhizomes won’t rot.

Reblooming Irises can be grown in Zones 5 through 10, but need to be mulched in the winter to prevent soil heaving. Just before spring, the rebloomer needs to be fertilized, and then again right after blooming (fertilizer to be sprinkled and worked into the soil, not touching the rhizomes). In the dry months, the reblooming Iris needs water at least once a week, and sometimes twice a week.

Reblooming Irises may be transplanted at any time, but the ideal time is when the soil is at least 50 degrees Fahrenheit at night. Each rhizome piece should be placed 1-2 feet away from another. The tops of the rhizome must be kept slightly exposed, with the roots spread downward in loosened soil that drains well. The newly transplanted rhizomes should be lightly watered in. Beds or reblooming Irises need to replanted every four years. The years and plants can be staggered, so the whole bed is not being replanted all at once.