Kumquats (also known as cumquat) are some of the easiest fruit trees to grow in garden pots. Kumquat trees are beautiful, with dark, glossy green leaves and bright orange fruit which is both gorgeous and delicious. Most commonly grown, Nagami kumquats have oblong fruit, which when ripe, has a sweet, edible skin and a sour fruit inside. They can be eaten whole, made into marmalade or used in other dishes.
Kumquats are hardy to 10 F and should be brought inside or protected if temperatures dip lower than that.
When grown in the landscape, kumquat trees can reach 8 feet tall and 6 feet wide. Grown in pots, their size will be smaller.
Kumquat Trees Like
- Full sun but will withstand partial shade
- Protection from the wind
- High-quality potting soil
- A large garden pot with good drainage
- Consistent watering - soil should be damp, not wet
- Regular fertilizing (except during the heart of winter)
- Will survive down to 10°F, though likes warm temperatures in summer
Kumquat Trees Dislike
- Wet feet (too much water will kill them)
- Not enough or too much fertilizer
- Strong winds
Sun and Temperature: All citrus trees love sun - the more the better, though kumquats will tolerate in partial sun, they will be happier in full sun. Kumquats will survive temperatures down to 10 F, but it is recommended that they only be kept outside all year in zones 8-10.
In spring, bring your tree outside, and put it in a sunny protected spot when nighttime temperatures are consistently above freezing. It’s a good idea to slowly acclimate any plant to outdoor conditions by hardening it off.
When your plant is inside, you’ll want to give it as much light as possible.
This can be done by placing it in a sunny window (though be careful that too much direct sun can burn your plant), or by setting it under grow lights or shop lights fitted with one cool and one warm bulb. However, your kumquat will also survive if you give it bright, indirect sun.
Feeding: In the spring, feed your kumquat with a slow-release, all-purpose or citrus fertilizer. During the growing season, regular applications of a diluted liquid fertilizer, such as liquid kelp, fish emulsion or a seaweed and fish emulsion combination is a good idea.
Watering: Proper watering is one of the keys to growing any citrus plant, but particularly those grown in pots. The aim is to keep the soil moist but not wet. Stick your finger into the soil, at least up to the second knuckle. If you feel dampness at your fingertip, wait to water. If it feels dry, water your plant until you see it run out of the bottom of the pot. If your plant is indoors, particularly in winter when the heat is on, misting the leaves with water can help keep your kumquat tree happy. It's also a good idea to use pot feet, so your plant doesn’t sit in water.
Harvesting: Kumquats are ripe when their skin is a deep orange color and the fruit is slightly soft to the touch.
Use a knife or scissors to cut off the fruit so you don’t risk damaging the plant by pulling off a larger piece than intended. Cutting off the fruit with a small piece of branch with leaves attached makes a lovely decoration.
Special note about kumquats: Though considered by many a citrus fruit, they are actually classified in the genus, Fortunella.