Jennifer Schultz Nelson
Extension Educator, Horticulture
Growing up I thought that all irises were purple with yellow fuzzy "beards". I also knew that my mom hated them. I spent a lot of time alongside my mom as a girl helping her dig up the persistent rhizomes. When she and my dad bought their house, the flower bed on the south side of the house plus a few oddball places around the yard were overflowing with the exceedingly tall purple bearded iris. While she thought the flower was pretty, her main issue with the plants were their relatively short bloom time, plus they took up so much room she couldn't plant anything else.
As I grew old enough to tend my own little section of garden, iris were near the top of the "do not plant" list. I saw ones I liked at stores and in catalogs, but stuck fast to my mom's ban on these flowers being planted again in her yard. The impervious ban began to crack when my grandmother passed away back in 1997. One living remembrance of Grandma Ann that I chose was a division of the iris that had grown for many decades in her yard. They were not the giant purple monsters of my youth, but small, petite yellow and bronze beauties. My mom was tolerant of them as long as I kept them under control. I was hooked. Plus they make me think of my Grandma, who I miss just as much today as I did then.
A few years passed, and my other Grandma passed away as well. Some iris from her yard came to my parent's yard as well. Not too long after that, last year in fact, I finally had a home of my own. I took divisions from those iris plants belonging to both grandmas to my house. It's funny how a little piece of plant can hold so many fond memories.
I have expanded my repertoire of iris far past the purple monsters of my youth and even past the dainty dwarf iris belonging to my grandma. Last fall, I was lucky enough to win an iris called 'Red Dazzler' in a raffle. It was a Louisiana Iris, one I hadn't heard of, but was curious about. One free iris ultimately led me to spend many dollars on expanding my iris collection.
Most iris grow from a thick modified stem called a rhizome which is very shallowly planted. According to the American Iris Society, there are three major iris classifications: Bearded, Aril, and Beardless types. Bearded are sub-classified based on height, but all have the fuzzy beards resting on the lower petals, or falls. Most bloom only once a year, but some have been bred for multiple blooming periods in a year. Aril types have a very sparse beard and have a wider range of colors than the bearded iris. Unfortunately, they will only grow in the driest and hottest parts of the U.S., not here in central Illinois.
The Beardless group is a big one. It is sub-divided into six groups: spurias, Siberians, Japanese, Louisiana, Pacific Coast natives, and species. All may be grown in Central Illinois gardens, with the exception of the Pacific Coast natives. They can only tolerate the climate of the west coast. Fortunately, the remaining groups have more than enough choices for most gardens. Plus they typically bloom after the bearded types, extending the iris flower season.
Spurias are very tall, up to five feet tall, and have flowers that resemble orchids. Colors range from white to yellow and blue. Some cultivars are deep wine or brown. Many have yellow accents.
Siberians are also somewhat tall, up to four feet in height, often in shades of white and blue. They prefer cold wet conditions, so they are clearly a good choice for planting near water. Their flowers are especially stunning en masse, and typically the lower petals, or falls are quite large, while the upper petals, or standards, are noticeably smaller.
Japanese iris have spectacular color combinations that I never knew existed in iris. I planted the cultivar 'August Emperor' near my pond and if it looks anything like the picture in the catalog, it should be a bright fuchsia pink with a white center accented by yellow and blue. These iris, like Siberians, prefer wet soil, and will even grow in shallow water! They prefer full sun.
The Louisiana iris is also one that likes wet feet. Native to the Gulf Coast of the U.S., they have particularly wide petals and prefer to planted deeper than other iris, about one inch under the soil and mulched. The cultivar I planted, 'Red Dazzler' should be a brilliant shade of scarlet red late this summer.
The American Iris Society does not classify Dutch Iris, they happen to have their own society and registry of cultivars. These are very different in form, growing from a small bulb instead of the typical rhizome. They come in a wide variety of colors, and will tolerate some shade. Bulbs are typically planted in the fall in rich, well-drained soil. If the soil is too wet, the bulbs may rot, particularly after flowering.
Iris have a few problems that can be devastating if not addressed. Iris borer is the major pest of iris, a moth larvae whose munching will cause wounds that invite bacterial soft rot to enter. Soft rot will reduce an iris to a smelly, mushy pulp in a short time. Fungal leaf spots are also common, which will hurt the appearance of the plant. Removing affected foliage and plants will reduce spread of iris borer, soft rot and leaf spot. Chemical controls such as acephate (Orthene) may be applied in April. Remember to practice good sanitation and reduce spread of pest and diseases by treating tools and even new plants with soaking in a 10% household bleach solution.
Another common iris problem is plants that won't flower. Usually this is due to the rhizome being planted too deeply, applying too much fertilizer, or overcrowding. With the proper conditions and varied cultivars and types, the iris season should extend through most of the growing season.