Chrysanthemums are a mainstay for color in the fall garden. Buy plants with unopened flower buds. Mums in full bloom may not produce additional flowers this fall. Plant in a sunny to partly sunny location and keep well watered. Deadhead regularly, and when all of the flowers have faded cut the plant back about a third. If the weather is mild you may get a few more flowers. Cut them back almost to the ground in late January, and they will bloom again for you next year in the fall. Or, pull the plants up and put them in the compost if they were planted for temporary color.