Gardenia jasminoides aka Gardenia

Gardenia jasminoides is an evergreen shrub in the coffee family. Gardeners know it as gardenia or cape jasmine. Its native range spans the eastern Himalaya, China, Indochina and Japan. Wild plants grow in woods, thickets, valleys and near streams. Garden plants often reach 3–6 feet [0.9–1.8 metres] tall and wide. NC State gives a larger range of 4–8 feet [1.2–2.4 metres]. Some plants reach 10 feet [3 metres]. Useful Tropical Plants reports an extreme height of 39 feet [12 metres].

Several stems form a dense, rounded crown. The bark adds little visual interest. Young twigs are green, then turn grey-brown, with paired brown buds. The thick leaves stay green through the year. Their upper sides shine, while their undersides look paler and duller. Leaves grow in pairs or whorls near branch tips. They have smooth edges and clear, sunken veins. Flower buds have a twisted, pinwheel-like form.

The waxy blooms open white or cream, then turn yellow. Their strong scent makes them useful as cut flowers. Many garden plants bear double blooms. Flowering peaks from late spring into early summer in cooler areas. Warm sites can support blooms through much of the year. Bees and butterflies visit the flowers. The oval fruits range from orange to reddish-brown. They hold red pulp and draw birds and other wildlife.

Give gardenias bright, filtered light or some shade. They need rich soil that holds moisture but drains well. Acid soil suits them best, though RHS also allows neutral soil. Shallow roots dislike disturbance and nearby tree roots. Shelter helps limit damage from cold and strong winds. Chicago Botanic Garden lists USDA zones 8–10. RHS assigns H1C and recommends indoor shelter below about 43°F [6°C]. Plants suit hedges, borders, pots and planting near paths. Their leaves provide year-round cover, and deer tend to avoid them.

Gardenias need close care and can suffer several pests. Whiteflies, mealybugs, scales, aphids and spider mites may attack them. Diseases include mildew, leaf spots, dieback, anthracnose and grey mould. Hard water, low iron or alkaline soil can yellow leaves. Changes in heat or water can cause bud loss. Flowers flavour tea and may be eaten or preserved. People also eat fruit pulp and use it as food dye. Flowers supply perfume oil; fruits also colour cloth. The fruit has a place in Chinese herbal medicine. Gardenias are toxic to dogs, cats and horses. Ingestion may cause vomiting, diarrhoea or hives.