It's the combination of wind and weak stalks. I don't think planting deeper would do any good. Some will fall over even without wind. Thin bamboo sticks make for a good support. I use iron "rebar" but it's not very attractive.

I've looked at the iris closely today and I agree I don't think I can do anything but figure out a support for them. I seen something I liked online, but it was a bit pricey. I'll just have to get my DH to make something, I'm thinking maybe 18" thin rods of metal and have him twist the tops of them into a loop and just place the bloom stalks through them for support. Keeping my fingers crossed!

~Rose

Where ever you find those green painted wooden stakes you will also find velcro green garden tape....allows you to
secure the stalk to the stake without a tight knot.

Takes about 1-1/2" piece per stalk.

Get the 48" stakes so you have enough to put deep into the ground and can stake the stalk up by the branching.

What's the best way to promote stronger stalks so they don't buckle under the weight of the flower?

For Gaetanol: the 3rd number in fertilizer is potassium and it says on the package that potassium promotes stronger stalks, also resistance to disease and winter damage. Certain varieties of iris have thick, strong stalks and others just seem to be thinner and weaker. For instance, I have an iris called Autumn Snowdrift - white with a tinge of blue around the edges - it is beautiful but really bad for weak stems. C'est la vie!

Mine flop over, here in Cincinnati, regardless of weather conditions. I buy an inexpensive bag of plastic zip ties and as soon as they hit the ground, I zip that stalk to other stalks or even leaves. I have had good results, now I can mow by them as needed.

When you divide and replant, do you cut back the flags (leaves) to 5-inches or so? Iris definitely do best when planted almost on the surface, with the top of the rhizome in the light. If you do not cut back the flags, there is no way at all the plants can get established in place without tipping over. They will send out roots very deep and wide to hold up the plant by the time new flowers and full leaves are there next year. Last September, I cut back every single one of my iris to about 5 inches to help eliminate the borers I had not so long ago that almost totally wiped out my iris. This spring I've had some of the most beautiful blooms ever and full lush foliage. These things can grow when it is time. Long ago, before I learned, I tried replanting after dividing without cutting back the flags and also had a problem with them falling over.