Kumquat: how to plant & look after a kumquat tree
The tiny but mighty kumquat packs a real punch with its bold flavour and myriad health benefits. Find out how to grow and care for your own kumquat fruits here.
Kumquat (Fortunella), or cumquat as they are known in Australia, sounds and looks pretty exotic. And the little orange citrus fruits don’t just look good; they taste delicious too! Kumquats are the smallest known citrus fruit, growing to a cute 1 inch or so in diameter. Here is how you can keep a kumquat tree as a houseplant and enjoy plenty of its fortunella fruits.
Kumquat: origin and characteristics
In the middle of the 19th century, an English botanist named Robert Fortune brought this cute citrus species from Asia to Europe. The scientific name for kumquat, Fortunella, was derived from his surname. However, like all citrus fruits, it has more than one name with Citrus japonica being another synonym for this plant. The kumquat’s little orange fruits are what make it so striking, as they are very aesthetically pleasing and are bursting with flavour. They taste like a slightly sour orange, but unlike oranges, there is no need to peel them, as the kumquat fruit’s peel and seeds are all edible.
In the wild, kumquat trees grow up to five metres tall, but as ornamental plants, they tend to grow no taller than one and a half metres. They look similar to other citrus trees with their oval, evergreen leaves. The number of thorns varies from tree to tree. With the right care, the kumquat’s large, fragrant flowers appear for two to three weeks around July or August. The little orange kumquat fruits later develop from these flowers.
How to plant and grow a kumquat tree
The most important factor to guarantee a healthy, happy kumquat plant and a successful harvest is the location. Kumquats are fans of warm and sunny weather, so make sure your home or patio are suitable before purchasing a plant. It is also a good idea to observe the course of the sun during the day; your kumquat’s ideal location is the spot that gets the most sunlight. Kumquat trees prefer soil that is permeable and slightly acidic, so a mixture of sand and humus-rich garden soil would be ideal. After buying your kumquat, repot it using this soil mixture in a planter that is about four centimetres larger than the plant itself with a drainage hole for excess water. Repot your kumquat roughly every two to three years, keeping the same steps in mind.
You can also grow your own fortunella tree from seed. To do this, dry the seeds of one kumquat for 2 to 3 days then sow them in moist soil. After a period of high humidity and temperatures of around 22°C, a young kumquat plant should develop. But bear in mind: it will take a few years before your kumquat plant flowers and bears fruit.
Kumquat tree care
When it comes to care, kumquats are similar to other citrus species. The kumquat has no problem relocating to the garden for the summer months, as long as it is moved to a safe wintering place before the cold weather sets in.
Watering a kumquat plant
One thing Fortunella plants cannot stand is waterlogging. Make sure you do not water your kumquat until the top layer of soil has dried out. A good way to test hydration levels is with a simple finger test. When you do go to water your kumquat, it is important that you do it thoroughly so that the roots get plenty of water. Water your kumquat plant regularly during the growing season, but less frequently during the winter months.
Fertilising a kumquat
Kumquats require regular fertilisation throughout the growing season. A quick and easy way to do this is to apply a liquid fertiliser to the soil when watering. Our Plantura Liquid Citrus Food suits the needs of the kumquat perfectly, as it contains all the essential nutrients, as well as microorganisms that strengthen its root growth. During the growing season, mix this liquid fertiliser with the plant’s water and apply every one to two weeks. However, you should stop fertilising your kumquat from autumn onwards to give the plant time to prepare itself for winter. Read our article on how to fertilise citrus trees for more info.
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Kumquats grow relatively slowly, so pruning is not strictly necessary. However, if you want to shorten the shoots, do it in February, before the flowers bloom. Make sure you prune your kumquat tree carefully, taking care not to damage it. You can remove withered branches all year round.
Just like other citrus trees, kumquats are not winter-hardy – meaning they are not well-adapted to survive our chilly winter weather. However, kumquats do need a cool indoor spot to rest in during the dormant period. A bright and cool place where the temperature lies between just above 0°C and 10°C, such as a garage that receives a lot of light, or an unheated conservatory or hallway, is therefore ideal for overwintering. You can find more plants for conservatories here. As a general rule, the warmer the place, the brighter it should be. If the kumquat is placed inside a room that is too dark or too damp, there is a risk of leaf loss.
- Water your kumquat very sparingly during the winter – only water it when the surface of the soil has dried out
- Fertilise your plant regularly with organic fertiliser during the summer months
- Do not fertilise your kumquat during the winter and reduce watering considerably
- Prune in February if necessary
- Overwinter in a bright spot between 1°C and 10°C
How to harvest and store kumquats
After about a year of maturing, you can pick the fresh, ripe kumquat fruits from the tree. However, the kumquat alternates, bearing fruit only every two years, so make sure you enjoy the fruits when they are ready to eat! If you can’t manage to eat them all fresh, don’t worry – kumquats and their delicious flavour can be preserved in a variety of ways. Kumquat jams and chutneys are a popular choice, but the kumquat can also be soaked in alcohol to make kumquat liqueur or grappa. Dried kumquat is another tasty option. To store uncooked kumquats, put them in a tin in the fridge, where they will keep for about a fortnight. If you choose to store them in a cupboard or pantry, they will only keep for a few days.
Discover everything you need to know about eating kumquats here.