When Should Indoor Gardenias Bloom?

Sunlight

• Gardenias need plenty of bright sunlight to bloom satisfactorily indoors. Position your potted gardenias within 3 feet of a south-facing window where they can receive four hours of direct sunlight each day and indirect or filtered sunlight for the rest of the day. The Purdue University Consumer Horticulture Department notes that it may be difficult for some gardeners to provide their indoor gardenias with the appropriate amount of sunlight in the winter; if this is the case, supplement the natural sunlight your gardenias receive with grow lights to ensure continued blooming.

Temperature

• Providing indoor gardenias with temperatures similar to what they would experience if grown outdoors is essential to successful cultivation and blooming. Gardenias perform best when exposed to warm daytime temperatures and slightly cooler nighttime temperatures. Program your home thermostat to maintain 70 to 75 degree Fahrenheit temperatures during the day and 62 to 65 degree temperatures at night. Exposing gardenias to unsuitably cool daytime temperatures results in slowed growth and yellowed foliage; unsuitably warm nighttime temperatures may cause indoor gardenias to drop their flower buds without opening them.

Irrigation and Humidity

• Gardenias require consistently moist growing medium and high humidity to set and open healthy blossoms. Water potted gardenias thoroughly each time you irrigate; hold the container under room temperature running water until you see water running from the drainage holes. Monitor the moisture of the growing medium daily; water whenever the top 1 inch of growing medium feels dry to the touch. Place potted gardenias on a shallow tray filled with pebbles and clean water; as the water evaporates, it increases the humidity around the plant. Never allow the bottom of the container to sit directly in the water in the tray as this leads to root rot and other cultivation complications. You may also use a cool mist humidifier to increase the humidity to your gardenias; run the humidifier for three to five hours per day in the room where your gardenias are kept.

Fertilization

• Fertilize indoor gardenias every two to three weeks, March through October, to give them the nutrients they need to bloom, and bloom prolifically, indoors. Feed your potted gardenias with a water-soluble fertilizer product that's specially formulated for acid-loving plants such as azaleas or rhododendrons. Consult the application and rate instructions on the fertilizer packaging to ensure that your gardenias receive the nutrients they need to thrive and bloom indoors.