CO-Horts Blog

Tuesday, June 25, 2019

Remembering the Irises of Springtime

By: Sherie Caffey, Horticulture Agent, CSU Extension-Pueblo County

One of my favorite parts of spring time is seeing all of the irises blooming in my neighborhood. So many people have beautiful clumps of these showy spring flowers and I love to see all of the different colors they can come in. These flowers are not only showy, but very easy to grow which makes them even better! By now the iris blooms have faded, but their unique fan like foliage still has me remembering their beauty.
Bearded iris
The two most common types of iris that people grow in Colorado are Bearded iris and Siberian iris. Both species come in many forms and colors. Their sword shaped leaves are very attractive when the plants are not in bloom. Both types of iris have three erect petals called standards, and three petals that droop down, called falls. The leaves are arranged into a fan shape.
The falls of Bearded iris have a neat looking, hairy center, which is where they get their name. They do best in full sun, and dry, alkaline soil. If you are from around here, then you know we have plenty of full sun and dry alkaline soil, making bearded iris a perfect addition to your landscape. Siberian irises have skinnier leaves than the Bearded irises, and prefer moist soil. You will often see them naturalizing near stream beds. They are also a great choice for your landscape if you have an area that stays pretty moist and gets full sun.
After your irises bloom in the spring, you should cut the flower stalks back so the plants can focus on storing energy for the next year. If you haven’t done this already, now is the time! If you want to cut the leaves back, wait until fall or late winter. Alternatively, you can go for a more natural look and not cut them back at all. The old leaves will end up acting as a natural mulch and eventually break down and improve your soil.
Siberian iris
Every three to four years, you will have to divide your iris clump so that it does not become overcrowded. It is best to divide after blooming is finished for the year, but no later than August. Use a garden fork to gently lift each clump of leaves from the soil, below ground you will find a bulb like structure called a rhizome. Only re plant healthy looking rhizomes. Trim the roots back a little bit, and also trim the leaves down so they are a few inches long. You can re plant this rhizome to extend your iris patch, start a new patch, or give them away to friends so they can start an iris patch. When you re plant them, the rhizome should be no deeper than one inch under the soil. Be sure all of the leaf fans face the same way. Spread out the roots and firm the soil around the rhizome. Need a visual? Check out this video:

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