Thank you, Doug, for all the suggestions.

I live in Cleveland, OH.

I will stop misting them and water my celosia by pouring water onto the soil.
They are planted in variously sized small pots all with drainage holes. I will
also try storing my plant water in a bucket overnight in case the chlorine is
harmful to them.

There is a hot water heater in the same room as the plants. No other appliance
in the room that uses gas. You are right, of course, these plants have been
indoors too long already. Much longer than any previous year.