The Calathea medallion is a popular cultivar of Calathea veitchiana, a foliage plant native to South America. Desirable for their large, showy leaves that feature creamy variegation on top and a deep red color underneath, these tropical beauties are often grown as houseplants in climates that can't support outdoor growth. Calathea medallions require warm, wet environments, according to information published by the University of Florida, or they will quickly decline. When these needs are met, however, the plant becomes a stunning showpiece in the home gardener's collection.
Place the calathea in a location where it will receive bright but indirect sunlight. Dappled shade is suitable, and sunlight that is filtered through a curtain is also acceptable. Intense, direct sunlight can scorch the leaves of the medallion, injuring or even killing it, according to Water Roots.
Use a well-draining potting medium for your calathea. This will help it retain just the right amount of moisture. Choose a mix that combines peat moss, loam and coarse sand.
Keep the temperature consistently warm--around 75 degrees Fahrenheit. Do not place the medallion calathea near hot or cold drafts, such as those from leaky windows or air conditioners, which can dry out the leaves.
Provide humid air for your calathea plant. Place the pot on a tray filled with pebbles. Add water to the tray so that the pebbles are barely covered with the water. As the water evaporates, it will add moisture to the air.
Water enough so that the soil is barely moist, but not muddy or overly wet. Too much water can cause a fungal disease that will rot the roots of the plant. Empty the water-catch tray immediately when the plant stops draining.