Irises
Tall Bearded Irises How to Dig, Divide & Replant
by Carrie Winter
Irises not doing well? Divide!
So your tall bearded irises simply did not bloom well this year, despite having produced many blooms in previous years…. What's the problem? If the clumps have been in place three or more years, it’s time to dig, divide and replant. The ideal time to dig is when the rhizome (actually an enlarged stem, but often called bulb, tuber or root by non-Master Gardener volunteers) is fully mature and on the brink of summer dormancy.
That time for the Charlotte, NC, area is July, not the most pleasant time for digging in the garden. However, since the rhizomes are growing near the soil surface, a clump is really quite easy to dig with a garden fork or shovel. Simply slide the fork or shovel under the clump, raise it up, and place the clump in a tub or on a plastic sheet. If you are digging more than one variety, it is important to keep them separate and properly labeled.
Iris planting
Remove the soil from the rhizomes and, with your hands or a knife, separate the clump into individual rhizomes with a fan of foliage. Examine each of the fans or divisions carefully for evidence of disease, especially rot. Discard these and the “mother” rhizome of the clump, saving all the young and healthy rhizomes. Trim the foliage of the fans to be saved into an inverted vee about six inches high.
At this point, the trimmed rhizomes can be washed, drained and dipped in a solution of 9 parts water to 1 part bleach, rinsed and drained again. The rhizomes should then be allowed to dry in shade that is open and dry. Most home gardeners generally omit the washing and rinsing steps. Rhizomes may be left out of the ground for up to several weeks, if necessary.
Now you are ready to replant. Before the dig or while the rhizomes have been drying out, the replanting area should be prepared. Your site should be well drained and receive at least six hours of full sun for maximum bloom. Dig the area to a depth of 10-12 inches and add soil conditioner, low nitrogen fertilizer and a dash of superphosphate. Lime is typically a useful and often necessary additive to Mecklenburg County clay to achieve a pH of 6.1-7.2. Work in the additives carefully so that none of the fertilizers will rest on the rhizomes.
The rhizomes of tall bearded iris should be placed 12-18 inches apart. If you have 3 rhizomes of the same variety, you may want to plant them in a triangle to achieve an immediate clump effect. The toe of each of the rhizomes should point to the center of the triangle. Each rhizome should be planted horizontally on a slight ridge so that the roots can spread out on both sides of the ridge. Cover the rhizome while leaving the upper surface of the rhizome exposed to the sun. Secure the roots in the soil and water well for the first week or two while a good root system develops. After that time, watering of bearded irises in the Charlotte, NC, area should not be necessary, making them an ideal plant for water conservation during our hot, dry summers.
You have chosen a sunny well drained location and replanted carefully, so what is left to do? A modest feeding as a side dressing in February and continuing removal of competitive vegetation (also known as weeds) should assure healthy iris plants with lovely blooms next April and May just in time for the local iris show. You might even win a blue ribbon.
-The rhizomes of tall bearded iris should be placed 12-18 inches apart.
-If you have 3 rhizomes of the same variety, you may want to plant them in a triangle to achieve an immediate clump effect.
-The toe of each of the rhizomes should point to the center of the triangle.
-Each rhizome should be planted horizontally on a slight ridge so that the roots can spread out on both sides of the ridge.
-Cover the rhizome while leaving the upper surface of the rhizome exposed to the sun.
-Secure the roots in the soil and water well for the first week or two while a good root system develops.
-After that time, watering of bearded irises in the Charlotte, NC, area should not be necessary, making them an ideal plant for water conservation during our hot, dry summers.
Happy irising!
Carrie Winter
Winterberry Iris Gardens is the home of Don and Ginny Spoon, over 6,000 different iris cultivars, and even more numerous seedlings of bearded irises. Both Don and Ginny, and their son Bryan, hybridize irises, and have received top awards with their hybrids from the American Iris Society and the International Competition in Florence, Italy. You may explore their web pages at www.winterberryirises.com where you may enjoy photos and articles about the Winterberry bearded irises grown and developed in northern Virginia.
Iris ‘Carrie Winter’ was introduced in 2011 and bears this description: ‘Carrie Winter’ (Don Spoon 2011) 36” ML Light yellow standards. Medium violet falls with lighter border and hairline darker edge. Haft area maroon and white zonal around beards. fertile. (Dreaming Rainbows X ((Son of Dreams X Clear Day) X Condottiere) $35.
© Carrie Winter 2011 all rights reserved
Carrie Winter, an Extension Master Gardener Volunteer for Mecklenburg County, NC, since 1998, has been raising irises since joining the Charlotte Iris Society (CIS) in 1993 when she was given a rhizome of the tall bearded iris ‘Beverly Sills’. Her iris collection now includes about 75 bearded iris and some species irises. Carrie served as president of CIS for many years and as secretary of Region 4 of the American Iris Society (AIS), and most recently, as Region 4 vice president of the AIS. In addition to giving programs on irises and their culture to garden groups, Carrie serves as a Garden/Exhibition Judge of AIS. Of note, in 2011 Don Spoon, a hybridizer from Winterberry Gardens in Virginia introduced a tall bearded iris named ‘Carrie Winter’.
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