Dividing and Moving Iris, and How to Transplant Iris
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The blooming of the bearded irises is something I eagerly await each spring. This year, I made a mental note to divide and move the irises in late summer or early fall, after blooming. Here’s how to divide irises—with step-by-step pictures.
Even though my irises were planted years ago and are terribly overgrown, the blossoms were still gorgeous this spring. However, dividing irises every 3 to 5 years is a normal part of iris care. This allows the clump to rejuvenate and bloom better (not to mention a way to multiply your irises to fill in the gaps).
Also, it’s helpful to avoid the iris borer which is a very destructive pest typically attracted to older, over-crowded gardens.
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All of my irises came from the gardens of family and friends, so they are precious to me, and I don’t want to lose them due to neglect.
When Should You Divide Irises
It’s important to divide and replant at the right time of year. In many regions, July and August are the best months to dig, divide, and transplant bearded irises. You can probably get away with dividing through mid-September, too. Do NOT divide in the spring. You must do this job post-flowering during the summer.
This is hot, heavy work involving a lot of digging, so I waited until the weather cooled down a tad before starting. My goal was to rework the iris beds, add some compost, eliminate the invading sedums and tree roots, and divide and replant the crowded rhizomes.
How to Divide Bearded Irises
First, dig the rhizomes up and check them for disease or insect damage. Try to dig carefully around the plants so as not to do any unnecessary damage to the rhizomes.
We found some borer damage and mushy rhizomes that were discarded.
Snap or cut off the old part of the rhizome, since it will not flower again.
The roots are quite long and will help anchor the newly planted rhizome in place.
Amend the soil with compost and dig a shallow hole or trench. Make a mound of soil in the middle to place the rhizome on, spread the roots out over the mound, and cover them with soil.
Leave the top of the rhizome exposed.
Next season’s plant emerges from the fan end of the rhizome so when replanting, face it in the direction you want plant growth to travel. Space the pieces 12 to 24 inches apart for tall types, closer for dwarf ones.
I planted mine closer, for a more immediate display, knowing that I will have to divide them again sooner.
It is easier to plant if you cut the tops back to about 6 inches tall.
Water well to settle the soil around the roots and continue to water deeply once a week until new growth appears. Once established, bearded irises are drought-tolerant and won’t need additional watering. Fertilize early in spring and again right after blossoming with compost or a low-nitrogen fertilizer.
It was sweaty work, even on a cool day, but so rewarding to see it done. We had enough leftover rhizomes to plant another bed on the other side of the stone wall. Next spring we should have twice the blossoms!
Learn more about growing irises in the Almanac’s Iris Growing Guide.
Robin Sweetser
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The next to last picture and the last picture show different soil levels. Should the tuber be covered with soil, or not? What about wood chip mulch?
Love the iris. Thank you for the help.
Thank you! I'm leaving the state and going South soon! plan to bring some of them down there in my garden there ! I did not know about cutting the tops off. THIS WAS VERY INFORMATIVE and HELPFUL to me ! Thank you for having this for us faithful gardeners out there ! Does anyone know why my bearded irisses did not bloom this year ? A lady in my church said they only bloom every 4 years ? I never heard of that. They did bloom last year ! All of them! I do feed them in March and June. as all my plants.
my irises bloom every year
I have known for a long time that iris should be divided in August, but never found any detailed instructions for how to go about it. Robin to the rescue! Thank you so much for the invaluable step by step direction with great photos!
I have Siberian irises. Noticed someone asked about dividing those. It's similar, but I didn't get small, tidy, individual stalks to replant. After 5 years, they slowed blooming and I could see the center was dead, an outer ring still green = time to divide. Ugh. Big chore. I only had 3 of them. Each had to weigh 40 pounds by the time I got them out, loaded with soil in the roots, etc. Tried different methods to separate clumps and get rid of the dead areas and after failing and struggling many times, I settled on a handsaw! Should have thought of that first. It worked. Put them all on tarps - lots of dirt, easier to clean up. Replanted the vigorous growth, dumped the dry, had lots for the back yard and front. The first spring, however, this year, only two flowers showed up after all that stress. The foliage is looking good, though. I'm feeling confident that they'll come back next year with a nice bloom. But seriously, be very cautious dividing irises or hostas or any well established perennial. I hurt my shoulder badly. Pinched a nerve. Weeks to feel better. Of course, that's just a cautionary message from a middle age dude! I should have grabbed that saw first thing. At least it's something that only has to be done every 3 to 5 years!
Thanks for the (very timely!) article on dividing and replanting bearded irises. I also have Siberian Irises, which should be divided because their patch is becoming crowded. Do I follow the same steps as for the bearded irises? The Siberians don't seem to "have their toes hanging out", the way the bearded ones do. Or should they? Thanks for your assistance!
Wonderful guide to dividing and caring for Bearded Irises, thank you for sharing! I am moving in the near future and want to take my Irises with me as they were also gifts, I wasn't sure how to go about it, but now I'm a lot more confident about tackling the project. Thank you!
I planted irises about a year and a half ago, in zone 7a -- Montgomery, AL. They have not bloomed.
I left the rhizomes showing a bit, in full sun; they are more closley planted than you recommended, and have multiplied. Just no blooms.
Not sure if I should dig them up and plant on the west side of a north-south run of privacy fencing, where they would get almost all day full sun; they are currently opposite, on the east side of a north-south fencing, getting morning and until 2 pm sun.
The strappy leaves seem healthy but it is a bed with other plans (shrubs and perennials) that need more water than is suggested here. Do they like it drier?
