Fortunella is a genus in the citrus tribe of flowering trees with several individual species, all known as kumquats. Some botanists prefer not to place kumquats into their own genus, instead classifying them as Citrus japonica and placing them in the citrus genus, with individual cultivars being considered subspecies. Disputes of this nature are not uncommon in the taxonomy community, and are the result of a variety of factors from competing names established by people vying for the right to name something to new discoveries made possible through genetic research.
Members of the Fortunella genus are native to Asia. These citrus trees can grow to a maximum of around 15 feet (four and a half meters) and produce aromatic evergreen foliage. Some species have thorns. Small white flowers develop into tiny orange fruits. The fruit of the tree can be eaten out of hand, and kumquats can also be used to make a variety of foods, from jams and jellies to flavored liquors. The fruits have a distinctive sweet and tart flavor and are typically eaten whole, as the pith common in other citrus fruits is not inedible in the case of the kumquat.
These trees like well-drained soil that has been amply worked with soil amendments. Neutral pH is recommended and kumquats often have difficulty growing in alkaline soils in particular. They require ample watering, and are frost-hardy to around 10 degrees Fahrenheit (-12.2 degrees Celsius), growing in United States Department of Agriculture (USDA) zones eight through 10 without difficulty. In cooler climates, planting Fortunella species in a sheltered or protected area is recommended in case there is a sudden cold snap.
Kumquats also grow well in greenhouses, aviaries, and conservatories. They take very well to container gardening and some people outside the hardiness zone for Fortunella may keep plants indoors in the winter and move them outdoors during the summer. These slow-growing plants are sometimes used in bonsai and they will produce tiny fruits if they are provided with the necessary levels of nutrition and care. For bonsai, wiring and pruning are recommended to achieve a desired shape.
Like other citrus trees, Fortunella is vulnerable to pests that prey on citrus, including a variety of insects and fungi. Trees should be inspected for signs of disease and the problem should be addressed before it has an opportunity to spread. A variety of products are available to deal with citrus pests, including organic pest control for people who prefer to use organic methods.