Gardenias

Gardenias

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More than a fragrance!

TEXT Gerald Schofield

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Gardenias are known for their fragrant flowers, and yet they are also exceptional evergreen shrubs for the garden.

The plant affectionately known and easily recognised as ‘gardenia’ is botanically called Gardenia augusta (previously G. jasminoides). This shrub with glossy green foliage and sweetly scented white flowers originates from many parts of Asia. Numerous hybrids have been bred during centuries of cultivation around the world, adding to the range and in some instances confusion pertaining to the correct naming of the plant. Gardenias are still one of the most popular of all fragrant flowering plants in cultivation. They grow well in many parts of South Africa and can adapt to most climates, except for the coldest and driest regions.

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Cultivation

Gardenias are ideally suited to morning sun positions or dappled shade. The key to happy gardenias is acidic soil conditions and cool root zones. This can be achieved by planting with acidic compost, mulching the root zone with pine bark, and feeding plants with blue hydrangea food. Regular watering during the establishment period after transplanting is important, and once the shrubs have become established they will need a good soaking if the leaves show even the slightest sign of wilting. Old or woody plants should be pruned back hard in spring. They will take two seasons to rejuvenate, but thereafter will perform with renewed vigour for a good many years.

Flowers last a few days before turning brown and falling off the bushes. The spent flowers can sometimes look a little unsightly and may need to be deadheaded to keep the plants looking neat and tidy. Gardenia ‘Golden Magic’ has large, fully double white flowers that turn a rich golden hue before completing their transition to brown. Few other shrubs, if any, can look as crisp and refreshing as a lush gardenia bush coming into bloom with snow white flowers contrasting strikingly against the glossy green leaves.

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Garden uses

Being attractive evergreen shrubs with varying growth habits, gardenias can be used for an assortment of different purposes. As medium to large sized shrubs they’re ideal for background hedges or screens, while they also make excellent subjects for training into topiary standards for pots or garden use. Some of the dwarf or low-growing forms are wonderful container plants and can even be used in large hanging baskets. Perhaps it should be noted that their heady fragrance can sometimes be overpowering, so careful placement is important. Plant them close enough to the home to appreciate the scent, but far enough away to prevent being overwhelmed. Cut flowers are often used in ceremonies and for adding fragrance to the home. Blooms are best floated in shallow receptacles where they will last for a few days.

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Indigenous gardenias

Oddly enough, the indigenous gardenia species are not as well known as their foreign relatives. There are a few species found growing in the bushveld regions, and as such our local gardenias are able to cope with dry and arid conditions. They are definitely some of the finest indigenous plants, but are grossly underutilised possibly due to the fact that young plants in nursery containers are not particularly good looking.

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Indigenous gardenias are predominantly small trees or large shrubs with rigid branches, sparse foliage and grey bark. They have a unique sculptured appearance in silhouette making them ideal specimen plants in the landscape. Large, single, white flowers appear from winter to summer, depending on the species and climatic conditions. The blooms are highly fragrant with insect-attracting properties. The two most commonly cultivated types are G. volkensii, which has grey-green fruit with conspicuous ribbing around the sphere, and G. thunbergia, which has pale grey fruit with no ribbing.

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Interesting facts

• The common name for Gardenia augusta is Cape jasmine, even though it originates from the East.
• The Afrikaans name for gardenia is katjiepeiring.
• The name ‘wild gardenia’ is used for the genus Rothmannia, which includes globosa (September bells).
• Infestations of twig wilters (stink bugs) are often found on gardenias. They live on the stems and branches, sucking sap from the plants causing them to wilt and die off. However, it has been documented that they don’t appear to have any adverse affect on gardenias.
• Yellow leaves (chlorosis) can be a problem with gardenias growing in marginal soil conditions. An application of iron chelate helps to rectify this.