Dividing Iris is easy and is a great way to get more to share. It also keeps your Iris healthy for great blooms! Here is an easy how to divide Iris Rhizomes step by step with video.
In this post I share how to divide Iris rhizomes, an easy step by step photo demonstration.
Iris are such a fun plant and so rewarding. Have you planted some and now they have started to not produce as many blooms as in past years? Iris usually need to be divided once every 3 years or so. That is not a hard and fast rule but a generalized observation for most.
I can start in August and continue on through September. Since I have so many Iris rhizomes that need dividing, spacing out the actual work makes it less of an arduous chore.
I live in the Sierra Nevada mountains of N. California at the 4500 foot level.
We get plenty of winter snow and cold, then some mighty fine summer weather averaging in the 80’s to low 90’s.
We are considered a Zone 7 (we have now been upgraded to Zone 8).
I have gardened with Iris for 35 years now.
Here and in the San Joaquin valley.
When to divide Iris Rhizomes
It is best to wait 6 to 8 weeks after bloom to divide, it gives them time to store up some energy.
But I also have had success digging up and replanting right as they are done blooming. I do better in remembering what color is where, I always say I am going to mark them while blooming and somehow never get around to it.
I have started to video during the blooming season so I can refer to the video to see what color is where. It works wonderfully!
This clump of Iris is done for the season. Some varieties will bloom again if you dead head, they are called reblooming Iris and it will be noted with the rhizome when you order or buy them. They really do rebloom and it is usually in September in my neck of the woods.
If you want to know what deadheading is then see this post, Dead heading for more blooms
Some people tidy the plant after blooming by shearing off the leaves, but I don’t. And here’s why….
The rhizomes are fed by the leaves and it is better to let them remain to soak up the summer sunshine and build up a food store for next years blooms. When the leaves yellow or look otherwise damaged you can shear those off but leave the healthy looking leaves to provide the food for the rhizome to store.
You will have bigger and healthier flowers next year.
Cure & Store Iris Rhizomes
If I am going to store or cure the rhizomes to give away I prepare a container with a bit of straw to lay them in. The straw allows air to circulate around the rhizomes which discourages rot. I also just lay them out on the ground or on our deck to dry. We live in a low humidity area so this is sufficient.
Some dust the rhizomes with sulfur or a powdered anti-fungal. I have not had to do that but you may need to consider it if fungus is an issue in your area.
Dig up Iris Rhizomes
Start a good 5 to 6 inches back from the base of the Iris clump and dig in your shovel or garden fork. Loosen around the clump as best you can. It is easier on your back.
Iris are not planted deep, they should be very near the surface but their roots can long. In the video attached you will see I really have to put some muscle into digging around the clump I am dividing.
Again, work around the entire clump to loosen it from the dirt. Once you have it well loosened it should pull up very easily.
You can merely shake off the dirt or hose off the excess dirt to inspect the rhizomes for rot or insect damage.
The roots can by quite long and I trim them back for easier replanting. I grab the roots at the base of the rhizome and cut what hangs below my fist. Then I trim back the leaves to about 6 inches long.
Sometimes rhizomes will separate themselves from the clumps voluntarily but usually I need to cut them apart.
Separate Iris Rhizomes
To separate and/or cut out diseased and old gnarly bits, use a clean sharp garden knife and cut it off at the joint.
It is easy to see where the joint is on this one, the rhizome narrows. (see example above)
It is highly recommended to thoroughly sanitize your cutting tools between cuts so you do not spread disease. Denatured alcohol or bleach water works best.
I have never had an issue with disease so you don’t see me cleaning between cuts.
I started to use the basket with straw but had way too many rhizomes so I laid most of the out on the shady porch to dry.
If you are not giving the extra Iris rhizomes away you can replant immediately, click here to see how I replant.
I will print a photo of the Iris in bloom and place it with the rhizomes I am giving away so whomever I gift it too will know what color it is.
If I am replanting in my garden I keep a hand drawn garden map of where I have put things. This past summer I kept a video garden journal and that has been excellent and helping me see what is where at any particular time of the growing season.
I wish you great success with your Iris, they are one of my favorites and they are so easy!
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