Gardenia jasminoides Pinwheel

Gardenia jasminoides Pinwheel stands out for its remarkable hardiness and its unusual flowering, consisting of beautiful star-shaped flowers that somewhat resemble large white periwinkles. This beautiful shrub can be grown in the open ground in many regions, but exclusively in slightly acidic soil and partial shade. Its lovely evergreen, dark green and glossy leaves, give way to its beautifully scented flowers, from spring to early autumn if the growing conditions are optimal. It is a medium-sized variety that easily fits in a large pot on the terrace or near the house, under a windowsill or near a doorway.

Gardenia jasminoides (synonym G. augusta) is a shrub from the Rubiaceae family, native to Asia. It is frequently found in the wild in Vietnam, southern China, Taiwan, Japan, and India, in mild and humid, subtropical to tropical climates. Its cultivation in China dates back at least a thousand years, and in recent years numerous American cultivars have been produced, more or less hardy, including 'Pinwheel'.

'Pinwheel' ('Piiga-i') was obtained before 2010 by Michael Dirr from the University of Georgia in the United States. Its breeder selected it for its hardiness, apparently tested in zone 6b (from -20 to -18 °C (-0.4 °F) (-4 to -0.4 °F)), but also for the duration of its flowering. It forms a small shrub with a flexible and rounded habit, reaching about 75 cm (29.5 in) in all directions after five years in pots, and 1 m (0 and 3 ft 4 in) in the open ground under good conditions. Its branches are quite flexible when young, but become brittle over time. The large, single white flowers, with a waxy texture, can reach up to 7.5 cm (3 in) in diameter. Their fragrance is powerful, deliciously intoxicating, both sweet and addictive. They bloom for a particularly long period of almost 5 months, from spring to October, abundantly from May to June, and then more sporadically. They appear solitary at the axils of the leaves, at the top of the branches, and are composed of 6 to 7 cream-white spatulate petals that fade to pale yellow. The flowers stand out well against its shiny dark green leaves. The leaves are entire, thick, leathery, averaging 5.5 cm (2.2 in) long and 2.7 cm (1.1 in) wide, with very prominent veins. Its bark is greyish. Gardenias have a very long lifespan and are more floriferous in its younger years.

Despite their somewhat demanding nature, Gardenias are among the most coveted shrubs by plant enthusiasts. It is undeniable that when the conditions are met, the gardenia proves to be one of the most beautiful plant species. However, the hardiness of certain varieties like Pinwheel represents an achievement in horticultural research. It should be moderated according to the duration of frost, exposure to dry and cold winds, and the water content of the soil. It is perfectly possible to successfully grow Pinwheel gardenia in the open ground, in a sheltered location and in non-calcareous soil, that almost dries out in winter. It also grows very well in pots, where it will withstand mild winters without damage, sheltered in a slightly heated conservatory or a cold greenhouse. It is often preferable outside of privileged regions to take it inside during winter, as a precaution. In the garden, camellias, rhododendrons, pieris, and kalmia will make excellent companions for this wonderful shrub.