The front garden in my first home featured huge, gorgeous bearded irises that framed both sides of the front door. The massive blooms were a deep purple hue, and you had to be careful not to brush them with your clothes as you went into the house. Sadly, that house and garden were torn down after we sold, but luckily, I had divided some irises and gifted them to my mom, who in turn gifted some to me once I moved into my current house. These beauties live on in my front garden. Now it’s time to divide again, so here are a few tips that explain how to divide irises.
Even though they produce a rather short-lived bloom, irises remain one of my favourite ornamental plants. And I’ve found them to be pretty hardy and drought tolerant. Years ago, when I divided my first bunch, I was in the middle of overhauling my whole front yard, so they sat in buckets of water, as recommended by my neighbour (some for a few weeks!), before I was able to replant them. Once nestled safely in their new garden home, the irises all survived the winter. One thing to note, however, is that irises may not bloom the year after they’re divided or transplanted, but be patient. They should eventually rebloom for you.
How to divide irises
Mid- to late-summer is a good time to divide bearded irises. You want to make sure that the roots have ample time to grow before winter. You can usually tell that your irises are ready to be divided when a clump looks overgrown, with rhizomes starting to grow into each other and popping up from the soil. They also may not produce as many blooms. Every three to five years is a good rule of thumb for dividing irises.
I’ve read articles recommending using a garden fork, but I use a rounded spade as that’s what I have in my tool shed, and I find I don’t risk splitting any errant rhizomes. What I’ll do is I’ll put the tip of my shovel in the soil a few inches from the clump, dig down, and lift, going all the way around in a circle doing this until I’ve managed to loosen a clump. I’ll pull out the clump and then by hand, I’ll carefully separate the rhizomes, tossing any dead leaves or rhizomes without leaves attached into my compost-destined garden trug as I go.
This is a good time to amend the soil, though you want to make sure you don’t add too much nitrogen, as it can cause soft growth and make the plant susceptible to disease.
For the rhizomes you decide to keep, cut the leaf fans back so they’re about four to six inches long. This helps the plant focus on growing roots before winter.
Replanting your divided irises
Irises like sunny spots in the garden that get about six or more hours of sunlight a day. They’re also pretty drought tolerant, so a nice option for sunny areas of the garden. Irises also like well-drained soil. Though they enjoy a slightly acidic soil, they thrive in most conditions.
To plant, dig a shallow hole and create a mound in the middle where the rhizome will sit. Place the rhizome on the mound with the roots in your hole. Cover the roots and then place a thin layer of soil over the rhizome. You want the rhizome itself to be just below the surface, lightly covered in soil. Push any errant roots under the soil with your finger (they tend to pop up sometimes!).
Plant rhizomes about 12 to 24 inches apart. If you plant them closer together, you just may find yourself dividing them sooner, but if you’re okay with that, then plant them as you will!
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Thank for the picture I’m visual 👍
You’re welcome! Glad it was helpful. 🙂
Same here!
Thank you!
I wish I had seen your post before the last time I divided my white irises! 🤷🏻♀️ I planted them too close together!!! Now, I need to do it again! 😊
Thanks for the great information. I will be supplying lots of neighbors later this summer
Got my dads house, like 2 doz iris, 6 blooms, all grown together, thanks for this info, i am also a visual. 💙
Hello. A nice woman at church just dug up a bunch of her iris plants for me. I’m noticing however that most are roots only without a rhizome. Is it worth planting the ones with roots only?
(This post and these comments have been super helpful!)
What a timely post! I have a huge clump of irises that I haven’t touched in the 9 years we’ve been here so it’s perhaps time that I did something about them 😉 Thanks for the tutorial, Tara!
You’re welcome, Margaret! Happy dividing!
Should you do this with Siberian irises?
Great question! I don’t grow Siberian irises, but the Canadian Iris Society provides some great tips on dividing here: http://www.cdn-iris.ca/siberian.html
Siberian iris are ready to divide when the center becomes bare. After blooming you can just dig them up shovel deep so you have lots of roots. Then cut them into smaller clumps, replant one in the original hole and now you have enough for all of your friends!!
Thanks so much, Cindy!
If you leave the top of the rhizomes out of the soil it helps them bloom. I like to leave some of it exposed so the sun can tell it to bloom. Just my own experience. I love the Iris too! Thanks for your work!
Great, tip, thank you so much!
I have bearded iris that are in a crowded.container and haven’t bloomed for about 3 yrs. Does it matter what time of year i dig up and divide them since there’s no blooms. Would like to Thin out now.(mid April ).
Thanks so much.
Hi Cory, Mid- to late-summer is best. But if you’re eager to thin sooner, just be sure to wait until the soil warms up. They likely won’t bloom for you this year if you transplant, but you may have luck in the next year or two. 🙂
Thank you for posting…this was on my to-do list but thought I had to wait until fall. Now I know!!
Do you have a separate bed for your Iris? I have them in with my other flowers and wonder if they are not blooming because the rhizomes are not getting enough sun. Thank you.
I have some in a separate bed and some in a new bed. The ones in the new bed didn’t bloom this year because I divided them last year. Sometimes it takes a year or two for them to rebloom. The garden where I took the divisions was business as usual this spring!
Will the rhizomes grow if still have roots but have been hacked apart?
I guess you can plant and see if it comes back!
We are in the process of reorganizing our perennial garden, so I am digging up all the iris and lily bulbs, and will replant them once we refill the garden with new soil. How should I store the bulbs over the next week or two until I can replant them? Thank you
Hi Paula, the first time I divided my irises and didn’t replant them right away, I put them in buckets of water, just around the roots (as per my neighbor’s suggestion). They were fine. Now if I were to do it, I’d probably plant them in soil in buckets until they’re ready to go back in the garden.
Schreiner’s, one of the largest iris growers in the world, warns that iris must not get too much water because it causes rot. So, NEVER put rhizomes in water for more than a few minutes.
I left them in a box in my kitchen for more than a season and they still bloomed once replanted, not the first year though.
I have a few large areas of irises that I need to divide. Rather than dig up the entire huge clumps, is there a recommended amount I could leave behind while I replant the newly divided rhizomes?
Thank you!
Hi Kim, it may be hard to not dig up the entire clump as they can become entangled. You may want to tackle one big clump at a time, gently disentangle them all and replant some in the original site, and then take the rest to the new area. How many you leave is a matter of aesthetics. 🙂
Thanks for the very much needed tips as I was given irises probably 8 years ago and never devised them but they just get bigger and bigger every year. That said a friend of mine requested a plant after they are done so this article is much appreciated.
I’m moving from Texas to Florida and want to take some of my bearded irises with me. I won’t be able to plant them (once dig up) for two weeks. How would you suggest I store them during that time? In water, soil, ziplock bag?
Hi Lori, Irises don’t like to be too wet or too dry. I would put them in a paper bag with some fresh soil to transport.
The last time I moved, I took all my iris with me. I dug them up, left them all together, and packed them into paper bags with some soil. When I got to my new place, I separated them and trimmed them before replanting. They were in the bags for about 2 weeks and they did amazing. I think I may have spritzed them with water 1 time but that was all.
I transplanted last fall hardly any bloomed this year?
Hi Marilyn, Irises don’t always bloom the year after they’re transplanted. Chances are they’ll be fine next year!
This is a great tutorial, to be never divided irises before and I have a huge patch of irises but I only get three or four blooms. I knew it needed to be divided.
Sorry for the spelling errors, I haven’t ever divided irises before, I have a huge clump and hardly any blooms. Your tutorial will allow me to replant these for future beauty in my garden
Hi Tara, I’ve had a bed of irises for about 15 years and they have only been divided once. Up until the past year or two they were doing pretty good. Unfortunately that was the time frame I was diagnosed with breast cancer and was unable to take care of my yard. Now they don’t bloom and I have noticed that they are rotting quite a bit. Do I need to move all of good ones to a new flower bed? I’m afraid that if I leave any in the original flower bed they won’t survive.
Hi Luann, I’m sorry you were unwell. I would dig them up and remove the ones that are rotting. Before moving the healthy ones to a new bed, I would try to figure out what the issue is. The American Iris Society has some advice for identifying and treating: http://www.irises.org/gardeners/care-classification/care/
Do you water them after they die back? Thx
I’ll give perennial gardens a good soaking here and there if we haven’t had rain. But generally I find irises to be pretty drought tolerant.
Okay, I’ve dug them up and shaken off the dirt. How do I divide the risomes, with a knife or just break them? Most of them are grown into each other. Thanx.
You can just crack them apart with your hands.
My MIL tells me I should have the rhizome top uncovered so the sun can encourage flowering. Have you found this to be the case? I’ve about to transplant mine from the temp bed back to their usual spot after having the garden redone
Hi Nina, I’ll lightly cover the rhizomes with soil, but I find they end up a little bit uncovered anyhow. It’s likely a transplanted iris won’t bloom that first year after you re-planted it.
I have trouble with wildlife eating bulbs (various kinds) that I plant. I have some established bearded, re-blooming Irises that have not been bothered. I purchased some (10″ X 10″ X 7 or 8 ” deep) plastic bulb cages. It seems like I might need one separate basket for each Iris bulb. I don’t see how the thick rhizomes can grow through the plastic top. Any ideas?
Is oct too late here in ny area? Been 55-70 degrees
Ty
I would probably wait until next year because they may not survive the winter.
I have irises in container pots,should I take them in the garage or just leave them outside?
Hi Sheila,
I would either nestle the pot in a garden and put leaves or mulch around to protect, or put it in the garage. I haven’t grown irises in pots, so I’m not sure how vulnerable they are to the freeze-thaw cycles of winter. Also, if the pots are terra cotta or clay you’ll want to protect those, too.
It is now early November. What problems would i have dividing the rhizomes now.
Hi Carolyn, I like to give divided irises time for the roots to become established before winter. Also, it’s possible they could heave as the ground freezes and thaws throughout the winter.
My neighbor is going to dig up her irises that I’ve coveted for a long time. It is spring however. How messed up will they be if I replant them this spring? or should I store in the garage until late summer and then replant them?
Hi Delma, if all threat of frost has passed, I would probably just get them in the ground, rather than worry about keeping them alive in the garage.
One of the urban garden locations in town has dismantled and gardeners were offered to take whatever they wanted. By the time I got there the raised beds,trellises, composters etc were gone but I was so lucky that no one took the Irises. It is early June in Colorado Springs Colorado and since the area is going to be bulldozed and so while ot is not the perfect time to divide Iris I decided to grab as many as I could. So my question is this…what do I do now with my horde of Iris? Will I have any success since I will be planting in hot summer? ( today was an “early” 89 degrees already)
Hi Karen,
Since it’s hard to store them, I would try planting and see what happens. Maybe plant some, if possible, in a site that gets part shade. But I’ve planted transplanted irises during a hot spell with success in the past.
If I break bearded iris rhizomes apart, should I treat the wound with anything and/or let it dry for a while before replanting?
Hi Tom, There are some tips here for treating the knife when you cut. https://extension.psu.edu/dividing-irises
My parents’ Irises have never been divided. They might be 30 or more years old. They bloomed in May, but the house will be sold in a few months and will be demolished. I would like to transplant them.
I dug around them, but it looks like the rhizomes are 3″ or 4″ in diameter. In a 2′ x 3′ area there were 30 or 40 flowers.
Can they be saved?
Stuart
Hi Stuart, I would say it’s worth trying!
Thank you for this info. Tomorrow a neighbor is allowing me to take as many purple iris asi want as long as I take the weeds too. I’m very happy.
Have you ever planted iris in a pot in the ground? My newest rhizome was severely delayed in shipping and in Idaho, I’m positive it’s too late to put her gloriousness into the ground. I’ve heard putting them in a pot for the winter and then planting the pot in the ground in the spring will still yield results. The last step being: at the end of summer, move her from the pot to her new permanent home.
My biggest question is when do I move her to the garden from indoors where she was given 6 weeks to root at 55-60° and then temp turned down to 40°?
I would move it outdoors as soon as possible. This could have been done from day one. Sinking the pot in the ground will provide enough insulation for the roots for winter, but you can also just plant it directly in the ground right now. Iris are tough plants and there’s really no need to coddle them.
Appreciate your article on cutting/ dividing iris. I keep pulling out the dead stems several times a week so they look good. I will cut them back so they get air. Thank you.
I appreciate the visual example, and your explanation was clear and organized. Thank you for sharing your knowledge.