hi! my folks raised mums for years for sale at local festivals and to local markets. Mom says- and I've done it with mine for years- after they are done blooming in the fall ( or they freeze out) DONT cut them down. The old stems protect and insulate the roots. Instead, mulch them a little with fallen leaves or pull up some of the mulch you might have in the bed around them. If they arent in too wet a spot, they probably will come back. In the spring,clean up the old stems. You should see tiny little frosty green mums peeking out at the bases of the old stems. To channel their growth into bigger plants and more, though smaller, blooms you can pinch the growing ends out on May1, June1, and July1...thats an easy way to remember. Two pinchings work well, too...say may1 and the last week of june.

Mums are genetically triggered to bloom at different times in the fall. As long as you don't pinch them too late (past July 1), they will bloom when they are ready. If yours bloom too late, then select for earlier blooming varieties. Cultivars are often listed as blooming in (1) early fall,(2) mid-fall, or (3)late fall.