Answer: Iris is generally dug and divided in late summer, but considering the circumstances I think I'd wait until late fall to dig the bed. The other perennials won't mind being dug at that time, as long as you cover the roots to keep them from drying out. Poison ivy doesn't seem to be as apt to bother people in the late fall, either, but I'd still caution you to cover all skin with protective clothing while you're working in the bed. Dig the perennials you want to save and place them on a tarp. Cover them so they won't dry out, then dig the entire bed and remove roots, stems, leaves and any other Poison ivy plant pieces you can find. Once the bed is completely cleaned out you can work in some organic matter (2"-3" spread over the entire bed and worked in to a depth of about 6"), and replant your perennials. If you find any sprouts of Poison ivy in the bed the following spring, cut them down or pull them out immediately to control the spread of the weed. Good luck with your project!
Q&A Library Searching Tips