Gardenias are one of the most fragrant flowers in the world, but growing a gardenia plant requires very specific care, especially if you want your plant to bloom. Gardenia plants are actually evergreen shrubs. Its leaves are glossy and dark green and the flowers range from white to yellow.
Gardenias may be grown inside or outside. Planting in a loose, well-drained organic soil is recommended. If grown outdoors, gardenias love warm days and cool, but not cold, nights. Daytime temperatures should be higher than 70 degrees and it should not get colder than 60 degrees at night. If you live in a colder climate, it's best to move the plant indoors. Gardenias also like humid air. If you live in a drier climate, you should mist the plant with a sprayer but do not get too much water on the leaves because it can cause spots and disease. Gardenias require at least an inch of rain (or equivalent watering) each week but it is important not to overwater or underwater because bud drop, the abnormal dropping of unopened buds, may occr.
While an outdoor gardenia needs some shade during the hottest part of the day, inside plants should have a lot of light but not too much direct sunlight.
You should plan on applying a lot of fertilizer throughout the growing season. Apply a water-based fertilizer every two weeks and also use an acid-based fertilizer at least once every three months. Anotherf good idea to test the soil's pH; it should be between 4.5 and 6.0. Sulfur may be added to soil to reduce the pH level.
Gardenias are also susceptible to insect infestation and disease. It is important to keep your gardenia as healthy as possible because insects will generally leave a healthy plant alone and move on to a weaker one. Gardenias can attract insects such as spider mites, aphids, mealy bugs, scales, whiteflies and thrips. Organic remedies or chemicals can be used to get rid of these insects.
Diseases that can affect gardenias include canker fungus, leaf spot, rhizoctonia leaf spot, sooty mold and powdery mildew. If canker sets in, the plant will have a swollen stem down around the base of the plant with numerous cracks up and down the stem. The stem will turn bright yellow above the affected area. Leaf spot has brown spots with a yellow circle or halo appearance around the spots. Rhizoctonia leaf spot appears with tan to brown spots that begin on the older leaves. Sooty mold causes black, thin layers of fungus to form over the upper surface of the leaves and is caused by whiteflies. Powdery mildew causes white, powdery spots on leaves. Many of these diseases will spread to other plants, so remove the dead plants and sterilize the soil before replanting. If you have any questions about a pest or disease problem, check with your local nursery to see if they have any tips for treatment.