Kumquats are members of the rue, or citrus family.
Native to south Asia, kumquats have been cultivated since the 12th century. Unlike oranges, or their giant cousins the grapefruit, kumquats are closer in size to olives. These somewhat tart fruits can be eaten whole, candied, chopped into a relish, fermented into a liquor, or cooked into a delicious marmalade.
Kumquats are small, cold-hardy citrus trees. They grow slowly and can reach 8 to 14 feet in height. Glossy evergreen leaves provide excellent color and shade. Fragrant white flowers appear each year, but watch out for thorns. Similar to many other citrus trees, kumquat trees protect their fruit with sharp thorns. Each tree can produce hundreds or thousands of fruits every year.
Types of kumquats
Scientists are still sorting out kumquat classification, arguing over whether different types of kumquats are cultivars or species, but we can all agree that there are round kumquats (Citrus japonica), oval kumquats (Citrus margarita), and bell-shaped kumquats (Citrus obovata). There is also a variegated kumquat that features more fruit, less peel, and no thorns. All kumquats are self-pollinating, so you only need one tree.
Unlike oranges, kumquats can tolerate temperatures as low as 19°F, right along with scorching hot summers, making them an excellent choice in the Bay Area. Before you try planting a kumquat tree from seed, you need to know that that generally doesn’t work out well. Instead, kumquats are usually grown from cuttings, layering, or other vegetative propagation method.
Kumquats can be grown in containers. Container grown kumquats can grow to 6 feet and produce fruit, if they are fertilized regularly.
Kumquat pests and diseases
Asian citrus psyllid is the most serious threat to citrus trees, as they can carry huanglongbing, a fatal disease. The diaprepes root weevil may also become a problem. Leaf miners, aphids, scale insects, and whiteflies are far more likely. Citrus diseases, such as armillaria root rot, alternaria rot, anthracnose, brown rot, citrus blast, exocortis, and phytophthora root rot may occur. Kumquats tend to be resistant to citrus canker and most citrus trees thrive in the Bay Area.
Consider adding kumquats to your foodscape this year for a lifetime of fragrance, color, and Vitamin C!
You can grow a surprising amount of food in your own yard. Ask me how!