Gardenias are evergreen shrubs or small trees that feature glossy, deep green leaves and large white or yellow rose-like flowers.
Dwarf varieties of gardenia are excellent as a low border in your garden bed or as a scented groundcover as they grow from 30cm to 60cm tall. However, if you're looking for real impact in your garden, some gardenia varieties grow more than 3m tall with flowers over 10cm in diameter.
Gardenias love a well-drained, humus-rich, acidic soil in a sunny or partly shaded position. Although gardenias can tolerate dry conditions, you should be watering them weekly, and even more in extreme heat. Just be careful not to overwater them as this can cause other problems.
Choose a fertiliser for acid-loving plants for your gardenias, and spread it in spring or summer for best results. If you want to spread mulch around your gardenias, go for a woodchip or sawdust variety. This will also add acid to your soil to help growth.
There's a range of garden pests that can affect gardenia blooms. Aphids can be a problem as they suck fluid from the plant and stunt its growth. If you can see them underneath the leaves, spray with an insecticide. You can also spray for mealybug and scale as well. If you notice that the buds are falling to the ground, this may be a sign of weevils or leaf hoppers, which can also be sprayed.
If your leaves are yellow, especially in spring, it could mean your gardenia is lacking water. Give it a good dose of fertiliser and a healthy water over a few days and the leaves should start to turn back to a glossy green.
There are also a few diseases that affect gardenias. Root rot is common in gardenias with poorly drained soil. This can cause the plant to yellow. You can save the plant by digging it up and pruning away damaged roots and then re-plant it in a spot with better drainage. Powdery mildew can occur when air circulation is poor around the plant. It will cause a white, fuzzy or powdery coating on the leaves and affect new growth. A good prune to thin out the plant will help solve this.