Gardenias are beautiful, fragrant--and finicky. These evergreen shrubs have earned a reputation for being difficult to grow, and rightly so, according to B. Rosie Lerner, a horticulturist with Purdue University. Still, with their large, creamy white flowers, glossy green leaves and wonderful scent, gardenias offer plenty of rewards for the home gardener who will take the time needed to care for the plant properly. These fragile plants can be killed with just one freeze, so they are often cultivated as indoor plants.
Provide Plenty of Light
Gardenias thrive in bright light. The plant needs exposure to at least six hours of sunlight per day to bloom properly, and preferably more than that. Many homes are too dark for the gardenia to even try to put forth the fragrant flowers that make the plant so desirable. Place your gardenia near a south-facing window or even under a grow light designed to simulate the rays of the sun.
Cool It Down
Gardenias are a bit of a paradox. While they thrive in full sunlight, they do not fare so well in the accompanying heat of the sun. These plants prefer cool indoor temperatures, with daytime temperatures in the mid-to-upper 60s and evening temperatures 10 degrees lower than those present during the day. Do not place your gardenia near any heat or air-conditioning vents, as cold or hot drafts can seriously injure the plant.
Wet the Air
Gardenias must have humidity to bloom. Dry air will cause the delicate buds to quickly wilt and drop from the plant before they even start to open. Place your potted gardenia on a tray full of pebbles and water, so that the pot is resting above the water on the rocks. Or, install a humidifier near the plant. Avoid misting the plant with a spray bottle, as this does not benefit it in the long run and may even lead to the development of leaf spot.
Feed It Well
Gardenias are heavy feeders and need regular amounts of water and fertilizer. Water your plant when the top inch of soil becomes dry. Do not let it sit in water, as this can lead to root rot. Instead, empty the water catch-tray as soon as the pot stops draining. Fertilize your gardenia with an acidic plant food formulated for blooming evergreens. Monthly feedings between April and November is a good idea, according to a care guide published by the University of Rhode Island. Feed your plant the correct amount according to the size of your gardenia as instructed on the package of plant food.