It's sad to see so many clumps of Iris in need of division! You could divide and share those expensive specimens, along with over grown Tulips, crowded Daffodils, and most other neglected and non thriving perennials!
Why just let hundreds of dollars worth of plant material go to waste? Some clumps of Iris could be worth 1000's in replacement cost, just waiting for some attention and division!
Maybe you have a young entrepreneur in your midst? Even if you don't want them digging in your gardens, you could share the extra plant material, and maybe inspire a new gardener! ....and a business person!
Don't be afraid, your perennials need to be divided for healthier blooms, and optimum root growth. You're not going to kill them, you're making them happier!
For best results, divide them in the Fall. If you want to do it in the Spring, that's ok too; just expect better blooms the following year.
For plants with blooms in formation, pick a rainy day, or water thoroughly and dig at dusk and replant asap for best results. Why at dusk? The shock of transplanting and the heat of the day, stress plants, and can cause severe damage; sun burn even. All plants will benefit from the same procedure; planting in the rain, or at dusk.
Happy Gardening! and share often!