The genus, Gardenia, contains around 200 species ranging in size fro mounding ground covers to trees of around 15 metres tall. Species can be found in Africa, Australasia, Asia and Oceania. Northern Australia hosts several native Gardenias.

The most commonly cultivated variety, Gardenia jasminoides (syn. G augusta) originates from China. Over the centuries hybrid varieties have been bred to give us Gardenia ‘Radicans’ at 25cm high, through to Gardenia ‘Magnifica’ at about 2 metres tall, with many sizes in between. I will focus on the cultivation of these.

They are renowned for their incredibly fragrant rose like blooms. These are either single or double whorls of clean white or occasionally golden cream petals. The flowers last well even when cut with a short stem, making them very popular in posies or as a button hole flower. Be careful not to bruise the petals.

The deep orange fruit, residual on the plant long after the flower has gone can be used for yellow dye in textile and foods. The petals are sometimes used to perfume tea.

Gardenias love humus rich, friable soil. The pH needs to be acidic, which is generally not hard to achieve on the Sunshine Coast.

Prior to planting, dig a manure rich compost 200mm into the soil and supply additional composted manure or organic fertiliser in early spring and again in early summer to ensure healthy foliage and abundant flowers. A common problem with Gardenias is a yellowing of the leaves. This is generally caused by a magnesium deficiency and can be remedied by a general purpose fertiliser with trace elements or a small dose of Epsom salts. Inadequate or inconsistent watering can also bring on leaf and bud drop. In long dry periods, mulch well to conserve water and either prune the plant back after flowering to reduce its requirements or water if permitted.

While they enjoy bright light, Gardenias prefer protection from the blasting afternoon sun of summer. Plant on the eastern side of a building or large tree.

In cooler areas, plant them against a north facing wall to protect them against the cold and frosts of winter.

They are shallow rooted plants. Disturbance to roots during flowering will cause the buds to drop. However, they do transplant quite well if moved or re-potted in autumn with the shallow roots providing a smaller, more manageable root ball.

Gardenias can be use for standards, hedging or as a back ground plant in garden beds. Any of the larger, common Gardenias make excellent specimen plants.

Pests, unfortunately, are a common part of growing Gardenias. Scale and mealy bugs will attack the upper reaches of the plant, usually resulting in the unsightly sooty mould. These pests are more prevalent if the plant is struggling for light or water or, if it is fighting against weeds. Sort out these problems first then if needed monthly sprayings with a horticultural oil when the problem is recognised will clear it up. Nematodes can also attack the roots of the plant, causing the leaves to yellow and fall. Companion planting with some annuals such as Marigold may alleviate the problem. In sandy soils, ensure dig a large amount of compost and manure into the ground before planting.

Aphids and White flies can also attack Gardenias.

Generally, the healthier a plant is, the less likely it is to be attacked by pests and diseases.

Find a spot outside a window or near your dining area to make the most of the heady scent from the Gardenia.