Hardiness Zone: 6a
Peggy from Chillicothe, OH
Black-eyed Susans are one example of a perennial that stands up well to the stress of being relocated. Technically speaking, the best time to transplant them is when they are dormant (early spring or fall). This will cause them the least amount of stress.
Planting them in the fall has its advantages, because it gives their roots time to become established before winter sets in, which will get them off to a faster start in the spring. Not-so-technically speaking, you can probably transplant Black-eyed Susans almost anytime as long as you do it during the coolest part of the day and give them plenty to drink. They may not bloom the first year after you transplant them, but they always seem to come around eventually.