You can continue planting perennials this month as long as you do it in the cool of the day (early morning and late afternoon to early evening). Divide and replant your spring-blooming perennials now, including your once-blooming bearded iris(you might want to wait till spring to divide your reblooming irises). Cut off any diseased or shriveled iris parts and put them into the garbage (not the compost heap).
If you have been pinching your mums, stop so they can set buds for fall bloom. They should no longer be pinched, especially after Summer began last month.