If you are looking to grow a plant that is both: a decorative object and a food source, and you live in a warm climate, you may want to consider the kumquat. It offers an attractive plant and delicious fruit all in one evergreen tree. You can also grow kumquats indoor, in pots, if you live in a colder area. If grown in pots, they must be dwarfed, not be allowed to become pot-bound and need faithful watering to avoid dehydration and regular feeding.
The kumquats are much hardier than other citrus trees. They require a hot summer, with temperatures ranging from 25 to 38 Celsius degrees (77 to 100.4 F), but can withstand frosts down to about -10 Celsius degrees (14 F) without injury. The trees also differ from other Citrus species in that they enter into a period of winter dormancy so profound that they will remain through several weeks of subsequent warm weather without putting out new shoots or blossoms. Despite their ability to survive low temperatures, the kumquat trees grow better and produce larger and sweeter fruits in warmer regions.
Kumquats are rarely grown from seeds as they do not do well on their own roots. They are grafted onto the trifoliate orange (Poncirus trifoliata). This has been found the best rootstock for kumquats and for dwarfing for pot culture. For this reason they are often known as “Dwarf Fruit”. Sour orange and grapefruit are also suitable rootstocks. Rough lemon is unsatisfactory in moist soils and tends to be too vigorous for the slow-growing kumquats.