Light: Calatheas prefer medium light - for example, at a tree-shaded window. Brighter light often spoils leaf coloring.
Water: During the active period growth water plants plentifully - as often as necessary to keep the potting mix thoroughly moist. In the rest period water moderately, enough to make the mixture moist, but allow the top half-inch of the mixture to dry out between waterings. Use lime-free water at room temperature.
Humidity: In warmer rooms high humidity is essential, and the foliage should be mist-sprayed daily. Rainwater is excellent for this, since it leaves no unsightly white lime deposit.