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Rutaceae FAMILY

Citrus japonica

Citrus japonica

Edibility
3/5
Medicinal
2/5

Safety & Hazards

None known

Cultivation Details

HabitEvergreen Shrub
Growth—

Citrus japonica is native to the subtropical climate of southeastern China. It is not a very cold-hardy plant, when dormant it can tolerate short periods where temperatures fall to around -5[1]. The new growth is much more susceptible to cold and can be badly damaged at around 0°c[1]. Kumquats are hardier than the various other cultivated Citrus species (such as the oranges and the lemons) since they cease growth when temperatures drop below 13°c. For best results, however, it is best to grow them in a climate with warm to hot summers and winter temperatures that do not fall lower than between 4 - 10°c[2]. This is because the fruit is sweeter when it ripens in warm conditions[2] Prefers a moderately heavy loam with a generous amount of compost and sand added and a very sunny position[1]. Prefers a pH of 5 to 6[1]. Plants are intolerant of water logging[1]. 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[PFAF]. Kumquats are widely cultivated, especially in China, for their edible fruit. There are many named varieties, and these can usually be divided into two main cultivar groups[3]. Round Kumquat Group (Formerly known as Fortunella japonica). These are usually trees 2 - 5 metres tall. The orangish yellow to orangish red, globose fruit is 15 - 25mm in diameter with a sweet-tasting skin up to 2mm thick[3], Oval Kumquat Group (Formerly known as Fortunella margarita). These are usually trees around 3 metres tall. The orangish yellow to orangish red, ellipsoid to ovoid-ellipsoid fruit is 20 - 35mm in diameter with a sweet-tasting skin around 2mm thick and an acidic flesh in 4 - 5 segments[3].

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. Cite as: Temperate Plants Database, Ken Fern. temperate.theferns.info. 2026-02-20. <temperate.theferns.info/plant/Citrus+japonica>

Pollinators

Insects

References

  1. [1]The New RHS Dictionary of Gardening. 1992. — Huxley. A. · MacMillan Press · 1992 · ISBN 0-333-47494-5 ↩︎Excellent and very comprehensive, though it contains a number of silly mistakes. Readable yet also very detailed.
  2. [2]Growing Unusual Fruit. — Simmons. A. E. · David & Charles; Newton Abbot. · 1972 · ISBN 0-7153-5531-7 ↩︎A very readable book with information on about 100 species that can be grown in Britain (some in greenhouses) and details on how to grow and use them.
  3. [3]Flora of China — Missouri Botanical Garden Press; St. Louis. · 1994 · http://flora.huh.harvard.edu/china/ ↩︎An excellent, comprehensive resource in 25 volumes. In addition to the botanical information the flora also gives basic information on habitat and some uses. An on-line version is also available.
  4. [4]Medicinal Plants in Vietnam — Nguyen Van Dan & Doan Thi Nhu · World Health Organisation · 1989 · ISBN 92 9061 101 4 ↩︎An excellent book, giving information on over 200 plants, their medicinal compounds and applications.
  5. [5]Cornucopia - A Source Book of Edible Plants. — Facciola. S. · Kampong Publications · 1990 · ISBN 0-9628087-0-9 ↩︎Excellent. Contains a very wide range of conventional and unconventional food plants (including tropical) and where they can be obtained (mainly N. American nurseries but also research institutes and a lot of other nurseries from around the world.
  6. [6]Fruits of the Earth. — Bianchini. F., Corbetta. F. and Pistoia. M. ↩︎Lovely pictures, a very readable book.
  7. [7]Medicinal Plants of China — Duke. J. A. and Ayensu. E. S. · Reference Publications, Inc. · 1985 · ISBN 0-917256-20-4 ↩︎Details of over 1,200 medicinal plants of China and brief details of their uses. Often includes an analysis, or at least a list of constituents. Heavy going if you are not into the subject.
  8. [8]Glossary of Indian Medicinal Plants (Including the Supplement). — Chopra. R. N., Nayar. S. L. and Chopra. I. C. · Council of Scientific and Industrial Research, New Delhi. · 1986 · ISBN - ↩︎Very terse details of medicinal uses of plants with a wide range of references and details of research into the plants chemistry. Not for the casual reader.
  9. [9]Chinese Materia Medica. — Stuart. Rev. G. A. · Taipei. Southern Materials Centre · 1911 · ISBN - ↩︎A translation of an ancient Chinese herbal. Fascinating.
  10. [PFAF]Plants for a Future — pfaf.org ↩︎