I want to redesign one of my flower beds. It currently contains early spring bulbs, perannials, foilage plants, etc. I would like to redesign it into a more formal flower bed and less of a cottage style. Since I have plants flowering from early spring to late summer, when would be the proper time to dig up the plants and redesign this bed? I am located in zone 5b. The normal frost free date is May 15th. I use soaker hose for watering and mulch the bed.