Fall Iris Care And Division

Irises are a beautiful addition to any flower garden.  They can be up to 48 inches tall, and bloom in early to mid summer.  This makes them an ideal centerpiece in a large garden, or perfect backdrop to a shallower plot.

On top of being a perfect visual reminder of spring’s promise of new life, they are also pretty easily taken care of once they get established.  This makes them perfect for a homestead flower garden that often receives much neglect as the vegetable gardens and orchards hog all the spring and summer attention.

Fortunately, they are forgiving and the little care that they do need can be done after the harvest is complete and the vegetable garden is put to rest for the winter.

Annual clipping
After the leaves have turned brown in late fall, irises can be cut to just above the ground level. Remove dead and diseased leaves by...

These irises are planted along a short terrace wall and serve as a backdrop to a deep garden.

Well past their full bloom, after the leaves turn brown in the fall, irises can be cut to just above ground level.  You can see in this picture, I like to cut mine to 3-4 inches.  Remove all the brown leaves, and any that appear diseased.

Dividing Irises
Before I divide my irises rhizomes, I spread them out on this cage-bottomed wagon and spray with water. Getting the rhizomes as clean as possible before division is important to...

I place my rhizomes on this cage-bottomed wagon and spray with water to get the dirt off.

Tall bearded irises propagate by rhizomes, and should be divided every four to five years.

Carefully loosen the soil around them with a spading fork.  If using a shovel, you could damage the rhizomes if you get too close.  Once loose, large clumps of irises with their rhizomes will easily come up.

Iris rhizomes like to grow into and wind around each other.  Cleaning the dirt off them is important to do before you start dividing so you can see exactly where you are cutting–you don’t want to accidentally cut too much off.

With a sharp knife, carefully divide sections from the central rhizome.  Leave at least one bud (or eye) and root on each section.

Remove all diseased or damaged roots.

Discard Rotten Rhizomes
These iris rhizomes have dead or diseased areas that will need to be trimmed or discarded. When trimming these, make sure...

Rather than whittle away at these, all were discarded.

Diseased or soft parts of the rhizomes need to be cut back until the healthy white part of the tissue is visible.  It is better to throw away any rhizomes that cannot be trimmed to a usable start, than to “try it anyway.”  As prolific as irises are, they will replace themselves in no time.

Check for iris borer, and remove any of this cream-colored dark headed moth larvae.  If found in a rhizome, discard the entire rhizome.  Be sure to check the soil your irises were lifted from (even if you did not see any borer), and destroy any larvae you may see.

 

Replant your rhizomes

Your irises are now ready to go back into the ground.

Irises want well-drained soil in full sun.  I like to till my dirt again while they are lifted out.  Unless you have very poor soil that you are planting your irises in for the first time, I would wait to fertilize your irises until early spring (and again after flowering).  If you feel you must amend your soil at this time, remember to be cautious with bonemeal, as it attracts critters (such as iris borer).

Plant your rhizomes horizontally.  The fan should point in the direction of plant growth.

In the north, rhizomes should have their tops visible when in the ground.  In the south, plant them an inch deep so that they are just below the soil surface. Rhizomes that are planted deep may grow, but will not flower.

It is suggested to plant irises 18 inches apart if you have the space.  I aim for 6-9 inches.  (I’m such a rebel, I know).

Irises can also be propagated by seed in the fall if you wish.

Mulch

Because rhizomes don’t like to be deep here in the north, I do not use my newspaper method with them, but I do give them a healthy layer of homemade mulch to deter any weeds.

Fall care for your irises. When & how to trim, when & how to divide, and more.

Your irises should now be ready to face another winter.

 

12 Comments

  1. Aren’t they just glorious! Mother Nature certainly is good to us, allowing us to recycle such a beautiful plant.

  2. Thanks for all this great info. I knew some of it it but learned a lot! I didn’t know that planting too deep won’t get you flowers. That explains a few waving leaves I found in the garden from past gardeners.

  3. Nice post. I love Irises. Thanks for the info on dividing.

  4. I just planted some that were given to me a couple of months ago and I think I planted them to the right depth. I guess next spring I will know if I did it right.

  5. My Iris has bloomed for the year, can I cut them back now or should I wait until the fall?

  6. I have divided and planted my iris around the trees in our back yard. I’ve also planted them around the postholes from our fence. I don’t think they have enough dirt around them so I plan on rearranging them by going a little deeper and improving the quality of dirt they are in. I live in Tn. When should I do this ?
    Also, most of them are so heavy when the bloom they fall over. Do you think planting them deeper will help ? Suggestions?
    Thanks.

    • I always suggest moving iris in the fall. Since I’m up north, mine are barely in the ground–you can see all the tops of the rhizomes. I would suggest if they are falling over, to clump them with one another so they will give each other support. In the south, you can bury them an inch deep. Any more than that and you’ll find that your iris’s may not bloom in subsequent years.

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