What is the expected dates which perennials can be transplanted this fall in zone 4a?
Stearns County Minnesota
Are you dividing some of your perennials before moving them? Depending on the plant type, some are best divided and moved in the fall, others in the spring. And some are fine to divide at either time. In general, plants that are blooming into the fall should be divided and moved in the spring. Plants blooming in spring or summer that have been done blooming for a few weeks can be divided in fall. When transplanting in the fall, there are no set dates for this to occur. The plant will need some time (ideally several weeks) to get established before the ground freezes. See the website below for best times to divide some perennials. http://www.extension.umn.edu/garden/landscaping/implement/DividingPerennials.htm
This year it seems too hot to transplant in August. What is your best guess for a timeframe or temp range.
Try in early to mid September.