They look great. Have they bloomed for you? How many colors?

Beardeds are like little potato storage tanks. Babies, also called toes, sprout off the sides and end of the mother rhizome after she finishes her spring bloom. If it's a vigorous cultivar these babies will grow large enough to bloom the following spring. Less vigorous cultivars may need 2 years for a baby to grow to blooming strength. So Mom's job is done. That rhizome will eventually shrivel up. It will never bloom again. Some cultivars produce 8 babies, others only 2. Occasionally 0 and that means that cultivar is over and done with.

So when a clump gets very large like yours it's time to discard old rhizomes . Doing a major lifting and dividing is perfect time to replenish the soil. I like to dig in a light scattering of bonemeal and tomato fertilizer (or rose). The bonemeal will be available much later to the roots. If using Superphosphate it is available almost immediately but burns new roots so needs a soil layer on top of that amended soil. 3 inches will be good. The strong babies you have broken away from the old mothers, and allowed to callus overnight in the shade, now get planted with the tops exposed.

All the red X rhizomes are getting trashed. I usually keep 3-6 rhizomes.

Bearded iris rhizomes should always be exposed to the sun or planted on the soil surface, not below it. If in a very hot climate, they can be lightly covered with a mulch but never should be completely buried in the soil - they will rot.

And those DO need to be divided. Beardeds generally need division in about 3 years if a healthy planting, otherwise they become overly congested and fail to bloom well. And the time to do that is late summer - the plants enter a period of semi-dormancy then and will handle the digging and removal/chopping or breaking of the rhizomes easily at that time of year. Enrich your soil before replanting and plant so that the rhizomes are just resting on the soil surface, firming in the roots underneath them well.

I wrote a reply this morning, but it does not seem to have posted! Thank you, all, for the insight. I live in Iowa, and the plant in the photo now has 8 or 9 buds on it. It blooms purple. I have a second, similar-looking clump that blooms burgundy - being new to these plants (we had a small group along the side of my childhood home but it was where no one ever saw it and was mostly ignored), that one in particular was thrilling our first summer here. I'm excited to divide them up after they're done flowering!

irisgal_z9,

Thank-you for that info about rhizomes...I had no idea that the old ones would stop producing like that!

So you said that the old ones would "shrivel up". Is it really necessary to discard them, or will just dividing to give more space for the babies be enough? I just worry that I might be discarding one that is still healthy/active!

Thanks.

PTW, In both picture you can see rhizomes without foliage. They are the old mothers who've not shriveled yet. They do not have to be tossed. They do no harm. Visually not attractive? There have been reports of foliageless firm rhizomes being chopped up and some pieces then producing a baby. When you see a truly shriveled rhiz. there will be no doubt it's not going to produce anything. Bottom side will have little holes where the roots used to be attached.

If different cultivars have been planted too close and begin growing over one another you have a gordian knot. But in both pictures I can see these beardeds are ones who like to travel and not stay in a neat clump or grow over one another. Which I have seen! The clumping ones. Those will use up available nutrients faster since they are not traveling to new territory. At any rate you are right. Dividing is to reform the clump and replenish the soil. The lesser bloom is misleading as it is only the old mothers in the middle of the patch who will not bloom again. So there's this big patch with scattered bloom instead of being concentrated. My beardeds sulk for a year after a major division. So I tend to shovel away 1/2 the rhizomes, leaving cut surfaces a day or 2 to dry before filling in the dirt.

shriveled rhizome separated (no side babies!)