Totally depends on where you live. I grew up in West Tennessee and we always considered mums short-lived annuals. I would buy them in the fall for their short-lived yet brilliant color, leave them in the pots they came in, and then throw them away when they died.

I just moved to northeast Oklahoma last year and I planted some mums in the ground alongside my pansies, totally expecting them to die off. Sure enough, those suckers came back 10x as big and beautiful this fall. (Their green foliage has been growing since the spring). Turns out they are perennials in this part of the country.

Hummm, posting in the Pennsylvania Gardening section is an indication of where I live or so I thought. But, Thank you.

Most mums ARE perennial regardless of where you live. The problems with them not wintering over is that they are typically sold in fall (bloom season!!) and so do not have sufficient time to establish a good supporting root system before cold weather arrives. Planting earlier in the season will help but hard to find then.

I would winter them over the same way you winter over any other non-hardy plant. Wait until flowers die and the plant goes through a good frost, cut everything back to just above ground level and store in a cold area (but above freezing). Light is not a requirement but cold temps (around 40F - not much higher or lower) and some soil moisture is. Then next spring you can plant them out in the garden and they should be fully established enough to winter over inground next season without concern.