@mystlw
I am sure that the cultivar in question grows well in many locations but it is always a good idea to check how well a cultivar that was hybridized in a different zone grows in other gardens near you with similar growing conditions as you have.
Perhaps you might try to get more details and information about how 'Mayor of Munchkinland' grows for the daylily farm you visited.
Perhaps some cultivars might not do well after division in zone 6.
Some cultivars are regional performers growing better in some zones than others or growing better in some conditions than others.
You might check the locations of the daylily growers that have listed 'Mayor of Munchkinland' in the past.
Some cultivars grow well in a region until there is unusual and less common weather and then they fail to recover well.
Some cultivars suffer from spring sickness severely enough and frequently enough that they are set back repeatedly.
