Care for a gardenia plant by placing it in a sunny location, amending the soil with the proper nutrients, watering the plant regularly, and giving the plant a humid environment. Fertilize the gardenia twice a year, and prune it for size.
When caring for a gardenia plant, select a location that has both full sunlight and high humidity. For an indoor potted plant, run a humidifier to increase the humidity and place the plant at a window with full sun exposure. Another way to improve humidity is to place wet pebbles in a tray and place the pot on top of the pebbles. If the soil isn't well-drained, add compost or peat moss. Mulch a newly planted gardenia with 2 to 3 inches of wood chips or pine needles to inhibit weed growth and maintain soil moisture.
Water the gardenia regularly, at least once a week, and avoid wetting the leaves. Water an indoor gardenia from below to prevent splashing. Fertilize the plant in early spring and early summer. Cut back any dead wood to keep the plant to a manageable size. Check the plant's leaves for pest infestations such as aphids, spider mites and mealy bugs. Use pesticides as needed by following the manufacturer's instructions.