Fortunella japonica - (Thunb.)Swingle.

(Thunb.)Swingle.

Round Kumquat

Rutaceae Edible: Fruit

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Carnegie Museum of Natural History

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The New York Botanical Garden

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The New York Botanical Garden

Description

Fortunella japonica is an evergreen Shrub growing to 2.5 m (8ft 2in). See above for USDA hardiness. It is hardy to UK zone 9 and is frost tender. It is in leaf all year. The species is hermaphrodite (has both male and female organs). Suitable for: light (sandy), medium (loamy) and heavy (clay) soils. Suitable pH: mildly acid, neutral and basic (mildly alkaline) soils. It can grow in semi-shade (light woodland) or no shade. It prefers moist soil.

Edible Uses

Pectin. Fruit - usually cooked and used in jellies, preserves etc or used as a flavouring, but it can also be eaten raw. The whole fruit, including the peel, is eaten. The fruit is acid whilst the peel is sweet. The peel is golden-yellow, smooth, thinner and somewhat sweeter than the oval kumquat, F. margarita. The fruit is rich in pectin and makes excellent marmalades and jellies. Vitamin C content is up to 0.24 mg/cc. The fruit is about 4cm long.

Medicinal Uses

Antiphlogistic Antitussive Antivinous Carminative Deodorant Expectorant Stimulant Vitamin CThe plant is antiphlogistic, antivinous, carminative, deodorant, stimulant. The leaves and fruit contain an essential oil, whilst the fruit also contains sugars and organic acids. The fresh fruit is antitussive and expectorant - in Vietnam it is steamed with sugar candy and used in the treatment of sore throats. It is said to be very good for infants.

Distribution

E. Asia - China, Japan.

Where It Grows

TEMPERATE ASIA: China (Guangdong Sheng, Zhejiang Sheng), Hong Kong

Cultivation

Prefers a moderately heavy loam with a generous amount of compost and sand added and a very sunny position. Prefers a pH of 5 to 6. Plants are intolerant of water logging. This species is not hardy in the colder areas of the country, when dormant it tolerates temperatures down to about -5°c. The young growth in spring, even on mature plants, is frost-tender and so it is best to grow the plants in a position sheltered from the early morning sun. Kumquats are widely cultivated in China for their edible fruit, there are many named varieties. The plant is less vigorous, somewhat thorny and considerably more cold tolerant (the report gives no details of what this is in comparison to!). Kumquats are hardier than the various Citrus species since they cease growth when temperatures drop below 13°c but, for best results, it is best to grow them in a climate where temperatures do not fall lower than between 4 and 10°c. This is because the fruit is sweeter when it ripens in warm conditions.

Propagation

Seed - best sown as soon as it is ripe in a warm airy position in a greenhouse. When they are large enough to handle, prick out the seedlings into individual pots and grow them on in a greenhouse for at least their first two winters. Plant out in late spring or early summer after the last expected frosts and give some winter protection from the cold for a year or two.