Calatheas, also called zebra plants, are tropical plants that consist of about 300 different species. Grown as houseplants in most regions, calathea plants are prized for their variegated, colorful foliage and reach a height of 6 to 36 inches at most. The calathea medallion variety has dark-purple foliage with a prominent silver-colored midrib, or central leaf vein, on the round to oblong leaves. Calathea medallion plants enjoy lower light levels, high humidity and moderate soil moisture.
Position the calathea medallion plant in indirect sunlight. Keep the plant away from direct sunlight because this will scorch the leaves.
Maintain air temperatures around your calathea medallion of 60 to 70 degrees. Place the plant beside a humidifier, or set the pot on top of a drainage dish filled with water and gravel, to keep the air around the plant humid.
Water your calathea medallion plant once each week or when the top 2 inches of soil begin to dry out. Water the plant using room-temperature, fluoride-free water, applying water to the soil until it begins to drain from the bottom of the pot.
Re-pot your calathea medallion in the spring when its roots become crowded in the pot, usually once each year or every two years. Transfer the calathea plant into a pot that is no more than 1 1/2 times wider and deeper than the current pot, filled with an all-purpose potting soil.
Feed your calathea medallion plant once each year in the spring with a slow-release 12-4-8 NPK (nitrogen-phosphorus-potassium) fertilizer, or a similar fertilizer with a 3-1-2 NPK ratio. Follow the dosage instructions on the label for houseplants.