The Gardenia genus consists of around 250 species, the majority occurring in the tropics of Africa and Asia. Mostly evergreen shrubs or small trees, they have opposite or whorled, simple, shiny deep green leaves. The fragrant large flowers have made this genus popular in cultivation throughout the world and an important florist’s flower. The tubular to funnel-shaped flowers can be white or yellow and are produced singly or in few-flowered cymes along or at the ends of branches. Gardenias can flower in summer, spring and autumn. The fruit is a leathery or fleshy berry with many seeds. Gardenias are useful landscape subjects and make wonderful container plants. They can be pruned on a tall trunk into topiary plants, kept as a bonsai, pruned as a normal shrub or grown as a tub specimen. Some species are used to scent tea and others are used in the treatment of influenza and colds in modern Chinese herbalism. A yellow dye was made from the fruits.
Growing Gardenia plants
Most Gardenia’s are very adaptable shrubs tolerant of sun or semi-shade and perform best in a well-drained humus-rich acidic soil. Gardenias need a protected position in the garden with some morning sun. An east-facing location is ideal, where the plant can be sheltered from the very hot afternoon sun. Acidity is important for these plants to thrive, it is important to check acidity when planting. pH can be lowered by adding peat moss or sprinkling used coffee grounds over the soil. Sometimes sulphur is needed to correct soil pH and should be used with care.
Gardenias are surface rooted and respond well to regular mulching with good quality compost and fertilizer when in growth, with adequate summer watering. Gardenias are sensitive to high salt levels in the soil which results from using hard water and fertilisers. To prevent salt build-ups, do not over fertilize and periodically leach the soil with rain water to wash out excess salts.
Gardenia plants require to be fed through spring, summer and autumn with Azalea & Camellia food. In cool climates grow in a heated greenhouse, as gardenias are frost tender. Pinching out the tips while the plant is dormant will cause the plant to become bushier. Pinching usually promote heavier blooms the following year. Propagate from seeds or leafy tip or half-hardened cuttings in late spring and summer.
One of the most asked questions about Gardenias is the yellowing of older leaves in late winter and spring. This is usually a sign that the plant is moving its magnesium to the new growth. In the beginning of spring feed with Epsom Salts (Magnesium sulphate), this will usually solve this problem. To avoid getting other nutrients out of balance, only apply Epsom Salts no more than once a year. Gardenia plants that are healthy will grow vigorously and are less likely to be affected by fungus problems. Planted in an ideal position, kept mulched and well fertilised helps most gardenias to stay robust. Always keep a close examination of the plants and deal with problems as soon as they materialize.
Gardenia florida is a very attractive beautiful shrub up to 1m tall. It is one of the best Gardenia’s for shape & flowering. It has a nice bushy, rounded growth habit to 1m wide. Flowers are beautifully perfumed, large and cream to white. Foliage is glossy green.