Gardenias – White Roses of the Tropics

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white-gardenia

It’s hard to grow roses in the tropics – unless you are lucky enough to live in a cool highland region – but several varieties of gardenia produce beautiful fragrant flowers that are similar to white roses.

Pictured above is a variety of Gardenia jasminoides that from a distance looks just like a white rose – but with no thorns of course!

There are actually over 140 species of Gardenia ranging from low shrubs to small trees, but Gardenia jasminoides is the species that is most popular with tropical gardeners.

Commonly known as Cape Jasmine or the Common Gardenia, this evergreen shrub usually grows about two metres in height, and 1-2 metres across, and thrives on acidic soils.

There is also a cultivar known as ‘Radicans’ which is much smaller, and a dwarf variety which can be used as a groundcover.

Cultivars of the larger shrub that produce the best white rose-type flowers include ‘Veitchii’ and ‘Plena’.

Gardenias like plenty of water, but need a well-drained spot in the garden, preferably with plenty of organic matter incorporated into the soil. Mulch the plants well to prevent them from drying out, and do not cultivate around the plant as this species does not like any form of root disturbance.

Fertilise regularly through the rainy season to combat leaching of nutrients and apply a trace element mixture containing iron at least twice a year. Iron deficiency will result in yellow leaves, as will growing the plant on alkaline soils.

While gardenias can be grown in full sun in the tropics, they will perform much better in half or three-quarters shade. Morning sun with afternoon shade from the house or a tree is ideal. Don’t plant gardenias too close to other plants because lack of air movement might cause fungal problems

Gardenias are often attacked by pests such as mealybugs, scale and aphids, and are susceptible to sooty mold, but don’t let this deter you from growing this very attractive shrub with its sweetly perfumed flowers and glossy leaves. Pest problems can be easily brought under control if caught early enough.

Many gardening books state that gardenias won’t produce flowers if the day-time temperature is over 22oC or if night-time temperature is over 18oC. This is not true. If it was, it would mean that gardenias would never flower in most tropical lowland regions. But it is true that temperature has an influence on the flower bud formation, and that is why gardenias in the sub-tropics produce many more flowers than they do in the tropics.

Images: David Astley

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