Choosing Iris in Minnesota
Sarah Heidtke, Dakota County Master Gardener
Late spring and early summer bring Iris blooms in Minnesota! Strolling through the University of Minnesota Landscape Arboretum, you will find many varieties of iris located in the Perennial Garden, and all around the Arb. In fact, the UMN Arboretum website arb.umn.edu lists 677 individual specimens currently on the website’s plant finder! You can plant iris in your own garden but which ones to choose? Read on for some considerations when choosing iris for your Minnesota garden.
Several different types of iris can be grown in Dakota County and around Minnesota. Sun exposure and soil conditions are important considerations when choosing which type to plant. Of course, there are so many beautiful colors and forms to choose from for your garden design too!
Blue Flag Iris (iris versicolor) is one of my favorite plants in my own garden - and is native to Minnesota. Blue Flag Iris can handle part shade to sun, and soils that are semi-moist to moist. This is a great option for the edges of rain gardens and marshes. (minnesotawildflowers.info)
Dutch Iris (iris hollandica) grow from bulbs, rather than rhizomes like other iris, and do best with full sun and well-drained soil. Most varieties are hardy in Zones 5-9, so they are grown as annuals in colder climates. I have had mixed results with this variety coming back in my Dakota County home garden, depending on the winter. They are a sweet bit of spring color.
Bearded Iris (iris or iris germanica) need full sun and well-drained, leaning to dry, soil. According to the Minnesota Historical Society, avoid over-watering once iris are established, and keep mulch away from the rhizomes in order to prevent disease and rot. It is quite a striking sight to see individual plants, or a mass of bearded iris standing tall (blooms on single stems can rise above 3 feet!)
Japanese Iris (iris ensata) are “beardless” and bloom after the Bearded iris, allowing the iris show to continue past July (Iris Society of Minnesota). They have larger, flatter, blooms and prefer more moisture in their soil than the Bearded iris (University of MN Extension).
Siberian Iris (iris sibirica) are also “beardless,” grown in part to full sun, and tolerate “a wide variety of soils, but will perform best when grown in moist fertile, organically rich, slightly acidic, well drained soils,” according to North Carolina Extension.
Other varieties of iris that can be grown in Minnesota and are listed on the Arboretum’s website, such as: Cattail iris (iris typhifolia), Orchid Iris (iris histroides), Dwarf crested iris (iris cristata), Sandy Iris (iris arenaria), Dalmation Iris (iris pallida), Roof Iris (iris tectorum), Spuria Iris (iris spuria), Blackberry lily (iris domestica) - are found in the perennial garden as well as the dedicated Iris Garden. You will also find an abundance of iris all around the arboretum. Something catch your attention? Use the Plant Finder tool at arb.umn.edu and find your way to a new favorite bloom if the time is right!
Here’s an iris to watch out for and not in a good way: Yellow iris (iris pseudacorus).
Yellow Iris is found in boggy areas and near waterways. It is a “regulated invasive species,” in Minnesota, meaning plants are “legal to buy, sell, transport and possess but may not be introduced into a free-living state, such as released into public waters (UMN Extension). Why worry about planting yellow iris? It competes with native shoreline vegetation and should be reported to the Minnesota Department of Resources if found. The Arb lists one occurrence of this species - on the Fern Walk. See you if you spot it next time you visit!
Wherever you’ve found a place to add an iris (or a few) to your garden, there’s a right iris for you. Happy planting!
Resources
https://northerngardener.org/irises/
https://plants.ces.ncsu.edu/plants/iris-sibirica/
Photo Credit: Minnesota Landscape Arboretum (1), Gayle Bergevin (2,6), Sarah Heidtke (3,4,5,7)