I love irises. They are my favorite flower. Dwayne doesn’t agree. He doesn’t understand why I would like something that only has a one day bloom. Of course, he likes the hibiscus, the poppies and many other flowers that do the same in our garden. Or at least only bloom for a couple of days. Doesn’t matter. I have a lot of them. Almost all of them came with the house. We have a few of the smaller variety that we got from our friend Bill before he died, but almost all of the full sized, giant, German Bearded Iris came with the mortgage.
Every so often I need to dig them up, clean them out and then replant them.. and not necessarily in the same spot. The best time to move irises are in late summer, mainly July and August. That gives them enough time to get established before the ground freezes. You can move them at any time, but they may not bloom for you if you move them in the spring. I had to move some irises one year in the spring. I think I got one bloom out of them that year and it was during the summer!
I mainly have Bearded irises. The flower is made up of three upright segments that are called standards, three dropping segments known as falls and the fuzzy growth that runs down the falls is called the “beard”. They grow from rhizomes, which are a kind of underground stem.
There are different classifications of bearded iris. Dwarf bearded iris are from 4 to 10 inches tall, standard-dwarf bearded are 10 to 15 inches tall, intermediate bearded are 15 to 28 inches tall and the tall bearded are more than 28 inches tall. They bloom in the spring with the dwarf bearded being the first to bloom, usually in mid-April to early May. The last of the bearded to bloom are the tall-bearded varieties and they are usually from mid-May to mid-June. And there are more and more cultivars that will bloom again in late summer or early fall. The leaves are thin and sharp and grow in fan-shaped clumps.
Bearded irises are relatively easy to grow, they do need to be divided every three to five years. If they aren’t, the plants become overcrowded and tend not to produce flowers. They can also be more prone to disease.
Whenever you chose to move the irises, dig them up carefully. Cut the leaves back to one-third of their original height. Clean the dirt off the rhizomes with a stream of water and cut them apart with a sharp knife. Get rid of the part in the center that has no leaves. Throw away anything that looks rotted or looks like it has borer damage. This is hard to do. I keep thinking if it is still solid, it is still good, but if there are signs of borers (holes in the rhizome) throw it away.
When you are ready to put the rhizomes back in the ground, put them in fertile, well-drained soil and full sun. The can tolerate light shade, you will get more flowers if they are in full sun. If they are put in wet and poorly drained sites they can end up with bacterial soft rot. Believe me, it’s disgusting. I had a lot of this after 2008. You can improve poorly drained soil by working organic matter, like peat or compost, into the soil before planting. You can also use raised beds. We have been talking about that for our garden. I think it would display the irises off quite nicely. I’ll let you know how that goes.
When you replant your iris, dig a hole large enough to take the rhizome and the roots. Build a mound in the center of the hole and place the rhizome on the top of the mound, spread the roots around the mound, cover with soil and water well. The rhizome should be just below the soil surface.
If you move the irises in the fall and want to remember what color the flower was, right it on the leaf with a permanent marker. I did that last year and then ended up not moving the irises. You definitely want to move them before the leaf dries up. It gets hard to read!
Repeated freezing and thawing of the soil during winter months can be tough on newly planted iris. They can be heaved out of the soil. To prevent any damage, put a light layer of straw on top of the rhizomes in the late fall. Remove the mulch in early spring so they can have plenty of air moving around them. The first spring of newly planted irises with bloom sparsely but should be in full bloom for later years.
Have fun with the iris!
This post was written by Eileen Loan on March 25, 2010