Beloved for their intoxicating fragrance and attractive, waxy, creamy-white flowers contrasting beautifully with their shiny, leathery, dark green leaves, Gardenias are irresistible evergreen shrubs or trees. Native to the tropical and subtropical regions of Africa, southern Asia, Australasia and Oceania, Gardenias may be fussy and quite temperamental in their cultural needs.
If your Gardenia's leaves turn brown or display brown spots, this may be caused by any of these reasons:
- Low humidity: Gardenias demand high humidity to thrive. Provide extra moisture with daily misting, set the plant on a tray of moist pebbles and/or use a humidifier. Extra humidity is important in keeping down spider mites that thrive under dry conditions.
- Water splashed on the leaves when watering the plant. Drip-irrigation will keep water off the foliage and flowers and prevents leaf spots.
- Poor soil drainage: Make sure your Gardenia soil is moist but well-drained.
- Insufficient light: Although a Gardenia plant prefers full sun, some shade is appreciated during the warmer months of the year or its leaves may scorch and its buds may fall off if they get too much sunlight. In hot climates, Gardenias grow best with morning sun and afternoon shade. In cooler areas, they can tolerate full sun, especially if their roots are covered with organic mulch. Gardenias growing in containers need bright light or filtered shade with no direct sun. Gardenias grown indoors should receive at least 6-8 hours of direct sunlight through a sunny window.
- Inadequate Ph: Gardenias prefer acidic soils with a pH between 5.0 and 6.0.
- Pests and microbial threats: Powdery mildew, leafspot and sooty mold can cause your Gardenia leaves to brown and wilt. Similarly, aphids, scales and spider mites can attack gardenia leaves. Check your plant for pests underneath the leaves and on the stems. Spraying your gardenia with an antifungal agent (such as horticultural oil with baking soda and insecticidal soap) can reduce the risk of infection or infestation.
To grow your Gardenia with success, make sure you follow these guidelines.