how to divide irises

How to divide irises

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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.

deep purple iris

My first iris via my first home’s garden, via my mom’s last garden, now in my current garden!

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.

knowing when to divide irises

A mess of rhizomes is a clear indication it’s time to divide your irises, especially when they’re pushing each other out of the soil!

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!).

replanting divided irises

I use scissors to cut the fan, before replanting my irises.

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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How to divide irises with Savvy Gardening



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18 Responses to How to divide irises

  1. Beverly Asleson says:

    Thank for the picture I’m visual 👍

  2. Margaret says:

    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!

  3. Barb says:

    Should you do this with Siberian irises?

  4. Cindy says:

    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!

  5. Cory says:

    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.

    • Tara Nolan says:

      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. 🙂

  6. Emily Bennett says:

    Thank you for posting…this was on my to-do list but thought I had to wait until fall. Now I know!!

  7. Cheryl Boulay says:

    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.

    • Tara Nolan says:

      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!

  8. Leems says:

    Will the rhizomes grow if still have roots but have been hacked apart?

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