I read the following on another website: “Some perennials are rarely divided or moved unless absolutely necessary. These include gas plants, peonies, tree peonies, foxtail lilies, goatsbeards, butterfly weeds, and bleeding hearts”... Why is this?? (i.e., why should dividing or moving these plants be avoided?) What OTHER plants would fall into this category?? How is a person supposed to know if this rule applies to any given plant?!?
Perennials with few fibrous roots or those with taproots generally don't transplant well once established, so it's best to leave them alone. The recovery time after dividing or transplanting them may be a couple years or more. Knowing which ones fit this growth habit is a matter of doing research on each plant. In addition to the ones you list, baptisia also is a tap-rooted perennial that doesn't transplant well.