Here is the secret sauce that separates the "meh" yards from the "wow" yards. Mums are photoperiodic, which is a fancy way of saying they're total light snobs. They need darkness to set their buds. If a streetlight or a porch light blares on them all night, they’ll get confused and stop blooming.
I once had a mum plant that bloomed only on the side facing the garage door, because the other side was by a window with a nightlight. It looked like it had a bald patch from bad sleep habits. So, if your mums are looking lazy, drape a dark sheet over them at sunset for a few weeks. They’ll get the hint and pop off.
Fall Mums 101: Your Complete Guide to Selecting and Caring for Fall