Now’s the Time to Divide Your Iris
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- August
- 31
As some readers may remember, I have a love-hate relationship with my irises.
This summer, after moving the driveway last year and finally relandscaping this spring and filling in where the old one ran, I figured out that much of my problem with my irises was their location.

They’re in the wrong spot — awkwardly sited by a previous owner and sitting in the middle of the lawn and blocking the view of the sage bed and a fairly nice stone wall we built a few years ago.

Worst of all, this tired, old, weedy clump of irises I’m not particularly fond of was the first thing I saw when I came out the front door. Time to go.

Here’s how the clump looked last October. Outright ugly.

My partner wanted to just rip them out and get rid of them completely, but as I began to dig them out I realized I couldn’t bear to part with every last one. So I saved some for myself …

… for a new bed lining the new driveway …

… and gave the rest away, even filling up the back of the pickup truck and taking them to a party, free for the taking.
Like many long-lived, hardy perennials, bearded irises do best if you divide them every three to five years. If you don’t, you’ll begin to see fewer and fewer blooms each year, especially in the dead center of the clump.
Luckily, iris rhizomes like to grow right at the surface of the soil, so it’s fairly easy to dig them up for division. And right now is a great time of year to do it.
If you get newly divided irises into the ground now, they’ll have plenty of time to settle in before winter. Well-established roots will keep them from being heaved out of the ground in next spring’s freeze-thaw cycle.
In the Hudson Valley, tall bearded irises need at least six to eight hours of full sun each day. They also like well-drained soil so that the rhizomes never sit in water.

Avoid using mulch in a bed of irises. This just encourages funguses and prevents the rhizomes from absorbing the summer heat they need to bloom.
New beds need regular watering, but, once established, irises are drought tolerant. Also, deer have never come near mine.
While you’re dividing your irises, why not add in a few new colors? New varieties — in an incredible array of color combinations — come onto the market every year.


Using a spade or pitch fork, dig up the whole clump of irises so you can see what you’re doing. Don’t be afraid to slice into the clump to get started; irises are fairly indestructible. If you like, hose off the roots so they are cleaner to work with and you can see if you have any problems with the rhizomes.

Using your fingers or a sharp knife, tease apart the clumps into smaller sections and get rid of any grass or weeds.

One big, old clump produces lots of new plants — for you and your friends and neighbors. Throw out any older, woody sections with no leaves or roots, or sections that are hollow or dried out, or mushy and black.

Trim back the foliage to about 4 inches and cut the rhizomes into individual new plants. Each new iris should have a few inches of rhizome, strong fleshy roots on the bottom and a fan of leaves on top.

Prepare a garden bed for planting and lay the new irises on top of the soil. Give them plenty of room to grow so that you don’t have to do this again for a few years.

Cover the new plants with about one-half inch of soil and water well. Don’t worry about digging them in too deep; the rhizomes will find their way back to the surface.

Now doesn’t this spot look better without the clump of irises?

Good riddance.



Bill Cary grew up in Louisville, Ky. His gardening was limited to growing parsley and impatiens on the windowsill of Manhattan walkups until the mid-1990s when he bought a rundown old chicken farm on 8 acres in the Hudson Valley. Now he spends his weekends chasing deer, hacking away at invasive shrubs and vines and wondering why he doesn`t have more meadow and less lawn.







Looks great. Are you going to put anything in its place, or leave it open for the sage bed?
Leave it open for now. I could see a low-growing evergreen shrub or dwarf tree there some day, but I want to see it through the winter with nothing there.