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 does not bloom, this may be caused by any of these reasons:
- Improper pruning: Prune your Gardenia plant when it is dormant, to promote branching and compact growth. This should occur after flowering in summer, but before the plant has time to set new buds. If you prune your Gardenia too late in the season, you will remove buds in the process of developing for the next season. Be careful - Some Gardenia varieties bloom twice in a season. Check what type of Gardenia you have before starting your pruning exercise.
- Bud drop: If your Gardenia's flower buds fall off just before they open, this may be caused by pest infestation (aphids, nematodes), excessive fertilization, over-watering, under-watering, poor soil drainage, insufficient light, unusually cool weather, rapid drops in temperature or very hot, dry weather.
- Hot and dry weather, unusually cool weather, quickly fluctuating temperatures: Gardenias perform best in day temperatures of 65-70°F (18-21°C) and night temperatures of 60-65°F (15-18°C). Flower buds will fail to form if the ideal temperature for Gardenias is not respected!
- Nutrient deficiencies: Gardenias like soil that is rich in nutrients. Add plenty of organic matter to the soil such as peat moss or manure to enhance the growth of your plant. Fertilize Gardenias every 2-4 weeks during their growing season (March to October) with a dilute fertilizer for acid-loving plants. Do not fertilize from November to February.
- Poor soil drainage: Make sure your Gardenia soil is moist and well-drained.
- Inadequate Ph: Gardenias prefer acidic soils with a pH between 5.0 and 6.0.
- Pests and microbial threats: Aphids, scales and spider mites can attack gardenias. 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.