Why Won't My Gardenia Bush Bloom?

The gardenia is beloved by Southern gardeners for its waxy white blossoms and exotic fragrance. However, this plant is very fussy. Your gardenia bush will not blossom properly unless certain conditions are met.

Climate

The gardenia is a semitropical, evergreen shrub that grows in U.S. Department of Agriculture hardiness zones 8 through 10. This plant thrives in high humidity and prefers mild daytime temperatures between 68 to 74 degrees F. For buds to form properly, the gardenia requires cool evening temperatures between 40 to 60 degrees.

Cultivation

The gardenia prefers full sun to partial shade and requires at least 4 hours of sunlight daily in order to bloom. It thrives in moist, well-drained, acidic soil. Fertilize your gardenia from March through August with an acidic fertilizer. The Clemson University Cooperation Extension warns that fertilizing in the fall produces early growth that can be damaged by cold winter temperatures.

Bud Drop

Bud drop, a condition in which flower buds fall off before opening, is a common problem with gardenias. Bud drop is caused by a number of issues, including inadequate light, low humidity, insect damage and overwatering. Extreme temperature changes — either too high or too low – also cause buds to fall.

Repot A Gardenia Bush

When the roots begin growing from the bottom of the flowerpot, it's time to repot the gardenia. The new flowerpot should be 1 to 2 inches larger in diameter than the previous flowerpot. Like other woodland flowers, such as azaleas and rhododendrons, gardenias prefer an acidic soil with a pH between 5.0 and 6.0. When repotting, use a potting mix formulated for rhododendrons or mix equal parts peat moss, compost and perlite. Once you've placed the gardenia in the new flowerpot, fill around the roots with the new potting mix and tamp gently before watering thoroughly. In their natural habitat, gardenias grow in moist soil. In addition, gardenias need high humidity levels or the buds will dry up and fall off the plant. If your home is extremely dry due to central heating or air-conditioning, place a cool-steam vaporizer near the plant to raise the humidity level in the room.