The kumquat tree (Fortunella sp. Swingle) is believed to be native to China. The tree grows between 8 to 15 feet in height with a shrubby, compact growth habit. There are thorn-less varieties available. The foliage is a light-green. The tree produces fragrant white blossoms that turn to small, oval fruit that resembles an orange in appearance. Each fruit measures up to 1 1/2 inches in diameter. The fruit can be consumed whole without peeling. There are seeded varieties and seedless available.
Plant kumquats in full sun. The trees prefer well-drained soil and will not tolerate water-logged roots. Organic matter such as leaf debris or peat moss should be added to the soil at the time of planting. Mix the organic matter at a ratio of 50 percent humus with 50 percent garden soil. The planting hole should be dug twice as large as the tree's root system. A one-acre orchard of kumquats can produce 8,000 lbs. of fruit annually according to BJ Jarvis, Pasco County, Florida, extension director, and Rhonda Rhodes, Pasco County master gardener.
Kumquats can successfully be grown in containers. Plant kumquats in a 15-gallon container for ideal growth, according to the Pasco County Cooperative Extension Service of Florida. Set the container a few inches off the ground for ideal drainage and air flow. Place the tree against a building to offer cold protection. Kumquats grown in containers should be grown beside other container-grown kumquats for additional wind and frost protection.
Wait one month to fertilize the kumquat tree after planting. Use a general purpose citrus fertilizer. Follow the directions on the label for application instructions. Water thoroughly after fertilizer application. Be sure that all fertilizer is watered into any tree planted in a container to protect against root burn. Fertilize the kumquat tree monthly during growing season. Keep the tree moist but not waterlogged. Apply a 2- to 3-inch layer of mulch around the base of the kumquat tree to keep weeds at bay and also help the soil remain moist. Do not apply the mulch directly against the trees trunk. The mulch should be 12 to 18 inches away from the trunk of the tree to help prevent the spread of disease.
Prune the kumquat tree after fruit harvest if desired. Kumquat trees do not require pruning except to improve the overall appearance of the tree or to remove dead wood. Pruning can also aid in allowing more airflow and sunlight to reach the various branches if the tree is extremely bushy.
During cold months the kumquat tree will go dormant. It will take several weeks of warm weather to awake the tree. Once the tree leaves dormancy it will produce new growth and flowers. The kumquat tree can withstand temperatures between 10 to 15 degrees Fahrenheit for short periods of time. The tree thrives when the temperature is between 80 to 100 degrees Fahrenheit. The warmer the weather the sweeter the fruit at harvest.