If you want to enjoy your mums again next year, follow these tips:
Plant mums (out of the pot) in a sunny area at least 18 inches apart, as they will spread. They will NOT bloom next year if planted in the shade.
Don't cut the mums back in the fall. To protect plants from freeze out, cover plants with 6-8 inches of loose soil or plant starter.
In SPRING carefully remove soil and prune out dead material. Plants that are healthy may be divided into 3 smaller plants.
Cut 1/3 of plant growth on June 4th and again on July 4th. Do not cut back after this. If you do not cut back at all, the plants will be tall and have fewer flowers.