Before bringing a chrysanthemum indoors, find out whether it is a hardy garden variety or a plant that needs protection. 'Chrysanthemum' on its own is not enough to choose a winter routine.
Inspect the pot, remove fallen debris and check for pests. Choose a position suited to the plant rather than putting it in the warmest available room because that feels protective.
Keep the label and the light
A cool, protected position still needs appropriate light and access for inspection. A forgotten pot in a dark corner is difficult to monitor, especially if its compost remains wet.
Check moisture as growth slows. Do not keep watering at the rate used while the plant was flowering outside. Equally, do not leave the root ball completely unattended for the winter.
If you have several varieties, label the pots before cutting back old growth. Their identities can become much harder to distinguish afterwards. Note where each plant spends winter and how it resumes growth. Those observations will help you choose a suitable arrangement next year without assuming every chrysanthemum responds alike.
Related reading: Overwintering Chrysanthemums in Pots and Garden Beds.