Citrus – Kumquat Fortunella margarita (Lour.) Swingle; Fortunella japonica (Thunb.)Swingle; Fortunella crassifolia Swingle; Fortunella obovata Tanaka; Fortunella spp. Rutaceae

Species description Kumquat are grown for their small, sweet-tart fruit that may be eaten completely with the rind. The rind is usually sweeter than the acidic flesh. Kumquats have a compact, low-moderate growth habit, and may reach only 8-15 feet tall and 5-10 feet wide. They have a long winter dormancy period, and though not technically a citrus, are considered to be among the most cold-hardy of the citrus, frost tolerant to 10ºF. The trees prefer sunny, open areas to reach full height and production. Leaves are dark green, simple, alternate, glossy. Sweetly fragrant flowers are 5 borne singly or 1 to 4 together in the leaf axils. Fruits are oval-oblong or round with green to yellow to red-orange peels and light orange inner flesh in 3-6 segments that contain few seeds.

Natural and cultural history Kumquats are native in the region from eastern Asia to southern China. They were introduced to Europe in 1846, and shortly thereafter into North America. Kumquats are currently cultivated in China, Taiwan, Southeast Asia, Japan, the Middle East, Europe (notably Corfu, Greece), and the southern United States.

Planting considerations and propagation techniques The trees are insect pollinated. Kumquats grow in a variety of soils, from light sandy to heavy clay, with tolerance for a wide range of pH. The trees do best in moist and well-drained soil. Kumquats are prone to zinc deficiencies, which results in smaller leaves. Kumquats can be propagated by seed, but to preserve the cultivar, cuttings should be grafted onto hardy rootstock. In China and Japan, kumquats are grafted onto trifoliate orange.

Water needs Kumquats need about 4-6 inches of water per month in the summer; they are generally not drought tolerant and need careful attention to produce well-developed fruit.

Care Kumquats are prone to spider mites, white flies, scale insects, citrus viruses, stem blights, leaf spot, and root rot. They need minimal pruning—only to remove dead and diseased wood and shape the tree for an open form.

Harvesting and processing The kumquat has a gently blend of both acidic flesh and a sweet rind; as such entire fruit, including the rind may be eaten raw, cooked, or candied, and can be used in jellies, marmalades, and preserves or as a flavoring. To combine the flavors of the flesh and rind, squeeze and massage just before use. After ripening, the fruit gradually loses water content, becomes richer in flavor, and is then best for making preserves. Kumquat fruit is naturally high in pectin. Kumquats are typically harvested from November to April in the northern hemisphere.

References and resources AZ Citrus. http://www.azcitrus.com Gmitter, F.G., J. Soneji, M.N. Rao, and S. Huang. Citrus spp., pp. 773-784. Eds. Janick, J. and R.E. Paull. The Encyclopedia of Fruit and Nuts. CABI Publishing, Cambridge, MA. Morton, J. 1987. kumquat, pp. 182–185. In: Fruits of warm climates. Julia F. Morton, Miami, FL. https://hort.purdue.edu/newcrop/morton/kumquat.html Page, M. 2008. Growing Citrus: How to Grow Citrus in Containers, Conservatories, and the Open Garden. Timber Press, Portland, London. Plants for a Future (PFAF). n.d. Fortunella margarita – (Lour.) Swingle. http://www.pfaf.org/user/Plant.aspx?LatinName=Fortunella+margarita

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