Gardenias are stunning plants with dark green, shiny foliage, and large white flowers that are also highly desirable for their exceptional fragrance. Situate them in an area where their fragrance can be enjoyed. Gardenias are not easy plants to grow, however. In Kansas, they must be grown in pots and moved inside for the winter as they are not hardy.
Gardenias must have acidic soil with a pH below 6 to thrive. The soil must also drain well, or the roots will start rotting. A mix such as half Happy Frog’s “Ocean Forest” and half peat moss works well. They should be repotted around once a year to continue growing larger. An organic mulch applied to the top of the soil will also keep the soil evenly moist and cooler.
Water must be consistent. If a gardenia dries out or is overwatered, it will drop leaves or buds and may even die. Make sure to add water until it comes through the drainage holes but don’t let the plant sit in the water. They should be checked often instead of watered on a schedule.
Gardenias need bright light but afternoon shade in the summer. Too much light will cause their leaves to burn. In winter, bright but indirect sun for 6 to 8 hours is necessary.
Fertilizer gardenias once or twice a month during spring, summer, and fall, but not during the winter. Use acid-loving fertilizer such as azalea food.
When indoors, they need a consistent temperature of 65 to 70 F in the day and 60 to 65 F to grow and bloom best. They may drop their blooms outside during the heat of summer. They also need high humidity, and since indoor environments are often dry, a humidifier is recommended.
Gardenias are susceptible to several insects and diseases. Watch for mealybugs, aphids, and spider mites in particular. Either a systemic insecticide applied at the beginning of the growing season or a foliar spray can control these pests, but the whole plant must be sprayed, including under the leaves. They may need to be resprayed every two weeks if the infestation is heavy enough.