Gardenia augustaCondensed Version:
Beloved for their intoxicating fragrance and creamy-white flowers, contrasting beautifully with their shiny evergreen, dark green leaves; gardenias remain firm favourites with gardeners in warm temperate and subtropical gardens worldwide.
Mature Gardenia augusta shrubs usually have a round shape, growing +-1.8 to 2.5m tall, with almost an equal spread. However, many garden varieties are distinctly different from the plant described above. These varieties vary greatly in size and growth habit, as well as in flower size. Flowers can be white or yellow; and single, semi-double, or double rose-like forms are available. Some gorgeous little dwarfs and ground covers make gardenias feasible for even the smallest of gardens, and because they grow beautifully in pots, even balcony gardens can have one.
In South Africa, gardenias thrive in our warm, moist regions, but grow well in most parts of the country, except for those coldest and driest regions. They are semi-hardy to moderate frost if planted in a protected position in the garden which is protected from freezing winds.
Select a site that receives semi-shade to sun, or morning sun. In very hot regions the plant will appreciate some shade in summer, especially during the hottest part of the day, but in cooler regions they are quite happy in full sun. Ensure that the planting site is protected from strong winds and that the soil drains well. Prepare the planting holes very well, incorporating lots of compost and a dressing of bone meal. Gardenias love slightly acid soil, so if your soil is not acid enough, use lots of acid compost.
They enjoy an evenly moist soil that is not soggy, so water them year round, but particularly in spring and summer when the plant is flowering. Gardenias are heavy feeders and need to be fertilised on a regular basis in summer with a balanced fertiliser. Mulching regularly will keep the root zone cool.
Picture courtesy Clarence E Jones III - see his flickr pageFull Version:
Description, History & Interesting Facts:
Beloved for their intoxicating fragrance and creamy-white flowers, contrasting beautifully with their shiny evergreen, dark green leaves; gardenias remain firm favourites with gardeners in warm temperate and subtropical gardens worldwide. The flowers open white, turning a creamy yellow as they age, and have a waxy feel, and orange-red fleshy berries follow the flowers, attracting birds and other wildlife.
This shrub is an excellent evergreen for the garden. and will produce flowers over a fairly long season from late spring to late autumn, with the main flush in the months leading up to Christmas. Warm summer breezes will waft the scent through the whole garden, much to the delight of everyone, and even a couple of blooms can perfume an entire room, making gardenias a favourite with florists.
This genus in the madder (Rubiaceae) family is found in tropical Africa, Asia, Australasia, and Oceania, consisting of about 250 species of mostly evergreen shrubs or small trees. Gardenia augusta is most commonly found growing in Vietnam, Southern China, Taiwan, Japan, India, and nearby regions of the subtropical eastern hemisphere. The common name Cape jasmine derived from the earlier belief that the plant originated in the Cape of Good Hope, South Africa.
Mature Gardenia augusta shrubs usually have a round shape, growing +-1.8 to 2.5m tall, with almost an equal spread. However, due to centuries of cultivation there are over 200 gardenia varieties available worldwide, many of which are distinctly different from the plant described above. These varieties vary greatly in size and growth habit, as well as in flower size. Flowers can be white or yellow; and single, semi-double, or double rose-like forms are available. Some gorgeous little dwarfs and ground covers make gardenias feasible for even the smallest of gardens, and because they grow beautifully in pots, even balcony gardens can have one.
(Gardenia 'Florida')
'Florida' produces large double white blooms and grows +-1.2 to 1.5m tall and almost as wide.
(Gardenia 'Golden Magic')
'Golden Magic' has double cream flowers that turn butter yellow with age. It grows +-80 to 100cm tall and +-80 to 100cm wide.
(Gardenia 'Professor Pucci')
'Professor Pucci' produces large, double pure white flowers in profusion. It grows + -1.2 to 1.5m high and +-80 to 100cm wide.
(Gardenia 'Impulse var Grandiflora Star')
'Impulse var Grandiflora Star' produces single, pure white, star-shaped flowers and grows +-50cm high and 30cm wide.
(Gardenia 'Four Seasons')
'Four Seasons' grows +-50cm high and 30cm wide and produces single pure white, star-shaped flowers.
(Gardenia 'Impulse White Gem')
'Impulse White Gem' has small single white, star-like flowers. It grows +-40 to 50cm tall and +-40 to 80cm wide.
(Gardenia 'Radicans')
'Radicans' is a compact and low-growing groundcover with very small leaves; +-30 to 40cm tall, and spreading +-80cm to 1m wide. It produces small (3cm) double white flowers and is often used for bonsai.
Uses:
The gardenia flower is a symbol of purity and sweetness and makes and excellent cut flower which is prized in wedding bouquets and flower arrangements, where it always adds a touch of elegance.
The flowers of some Gardenia species are used in Chinese herbalism to treat influenza and colds, and some are used to perfume tea. A yellow dye was made from the fruits.
In the Garden:
The Cape jasmine is essential in all romantic and perfumed gardens. It makes a beautiful freestanding specimen shrub to plant close to a patio, entrance, garden bench or window - where its shape and beauty can be appreciated, and where its fragrance can be enjoyed.
It also makes a good hedge or screening plant and grows easily in containers. Dwarf varieties and groundcovers look wonderful spilling over hanging baskets.
Cultivation/Propagation:
In South Africa, gardenias thrive in our warm, moist regions, but grow well in most parts of the country, except for those coldest and driest regions. They are semi-hardy to moderate frost if planted in a protected position in the garden which is protected from freezing winds.
Select a site that receives semi-shade to sun, or morning sun. In very hot regions the plant will appreciate some shade in summer, especially during the hottest part of the day, but in cooler regions they are quite happy in full sun. Ensure that the planting site is protected from strong winds and that the soil drains well. Prepare the planting holes very well, incorporating lots of compost and a dressing of bone meal. Gardenias love slightly acid soil, so if your soil is not acid enough, use lots of acid compost.
They enjoy an evenly moist soil that is not soggy, so water them year round, but particularly in spring and summer when the plant is flowering. Gardenias are heavy feeders and need to be fertilised on a regular basis in summer with a balanced fertiliser. Mulching regularly will keep the root zone cool.
Pruning is sometimes necessary to help shape your plant or to keep it a smaller size. It is important that pruning be done after the plant has finished flowering, or you may cut off newly forming buds.
Propagation is by semi-hardwood cuttings which root easily in moist soil during the warm summer months; or by seed sown in spring and early summer.
Problems, Pests & Diseases:
Gardenias are susceptible to several pests, primarily sucking insects. Insect attacks are aggravated by lack of air circulation in small walled gardens and courtyards. The presence of insects may also be a sign that your plant is under stress, so ensure that it is well watered and correctly fertilised. Aphids, whitefly, spider mites, scale insects, mealy bug and sooty mould are common problems, which can be easily controlled by spraying with environmentally safe soap and oil sprays. Use a sticker liker G-49 with your insecticide to help the poison stick to the glossy leaves.
Infestations of twig wilter (stink bugs) are often found on gardenias. They suck the plant sap, causing some stems to wilt and die. However, they don’t seem to have any adverse effects on the plants.
Gardenias are very susceptible to nematodes, especially in sandy soils. Nematodes are mobile worm-like microscopic organisms which attack the roots of plants. They are easily recognisable, causing wart-like lumps on the roots about the size of a match head. Signs of nematodes are wilting and yellow leaves which persist even after fertilising. Potent chemicals are not suitable for use in the home garden, so rather sow marigolds near susceptible plants and dig them lightly into the soil when they have finished flowering. Khaki weed also works well to help control nematodes.
Gardenia flower buds may go brown, drop, or fail to open. This is fairly normal and occurs mainly because the plant tends to keep producing flower buds right through autumn, even though plant growth is slowing. The plant will often hold these buds right through winter and drop them in spring. Bud drop can also be caused by weevil or leaf hopper damage.
Yellow leaves can appear at any time of the year, but are particularly prevalent in spring. Yellowing is generally attributed to a magnesium deficiency and is treated with applications of Epsom salts (sulphate of magnesium). If your plant has been planted correctly, is fed regularly with a good all-purpose organic fertiliser, and is watered correctly, yellowing of the leaves should not become a problem. It is especially important to fertilise in spring when the weather warms up.
Warning:
Gardenia augusta is listed by the California Poison Control System as being nontoxic to humans if ingested. However, the CPCS adds that even nontoxic plants may cause vomiting in humans and animals, and that ingesting plant matter can cause children to choke or gag.
The American Society for the Prevention of Cruelty to Animals lists gardenia as being toxic to dogs, as well as cats and horses. Because the ASPCA does not offer toxicity information for other species of gardenias, it is probably safe to assume that all species and cultivars may incur similar damage.