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Kumquat, a tiny, original citrus


Kumquat is a citrus for which you can eat the skin together with the cute fruits.

Key Kumquat facts

NameFortunella japonica
Family – Rutaceae (Rue family)

Type – fruit shrub
Foliage – evergreen
Height – 6 to 13 feet (2 to 4 meters)

Exposure: full sun        –        Harvest: November to January

The planting, repotting, care, watering and pruning of kumquat are steps to take to grow a very nice plant.

Planting and repotting kumquat

Most often, kumquat is grown in pots as a beautiful houseplant. In mild climates, you can grow it outdoors and harvest fruits!

Planting kumquat in pots

It is recommended to plant kumquat in a blend of soil mix preferably enriched with fertilizer.

  • The pot must absolutely have a hole at the bottom to avoid having the roots stagnate in water.

kumquat potAn ideal solution is to pour in a layer of gravel, clay pebbles or rocks. This ensures excess water drains well to the bottom.
Make this layer about 1 to 2 inches (3 to 4 cm) thick.

Anticipate repotting in a pot that is slightly larger than the previous every 2 or 3 years on average.

Kumquat in the groundPlanting directly in the ground

It will only grow directly in the ground in Mediterranean-type climates or tropical climates.
Although it has been seen to resist temperatures as low as 17°F (-8°C) and even 14°F (-10°C), it must necessarily be planted under wind shelter and in full sun.

In which case, mix soil mix into your garden soil and ensure that your soil drains well.
If it doesn’t drain well, dig a hole that is slightly deeper, and layer gravel, rocks, sand or clay pebbles along the bottom.

Pruning and caring for kumquat

Kumquat branchIt isn’t really necessary to prune it.

To rebalance the silhouette of your kumquat, prune lightly in spring after the harvest, or just after repotting if it is a potted specimen.

You can also input citrus plant fertilizer during the entire growing phase.

In winter, if you fear particularly strong freezing and it is grown in a pot, bring it in a cool and well-lit room where it never freezes.
Although the kumquat can resist to freezing temperatures, its fruits will fall with the first frost.

Watering Kumquat

Indoors, water regularly but not too much as soon as the soil is dry.

In winter, space the watering in order to let the soil dry up deep down before watering again.

Learn more about Kumquat

Kumquat fruitsKumquat is a small fruit shrub that bears edible fruit, and, which is rare for a citrus, the entire fruit is edible.
Indeed, not only the flesh but also the skin of the kumquat is edible.

Indoors and in a pot, simply set it in a well-lit spot but avoid direct sunlight during the hottest hours.

In winter, it needs relatively lower temperatures and would not resist the heat inside a house or apartment. Ideally you’d find a luminous room for it where the temperature won’t drop below freezing. A greenhouse or lean-in would be perfect, for instance.

Diseases and parasites of Kumquat

Smart tip about Kumquat

Regular adding of citrus plant fertilizer will greatly increase blooming and fruit formation of your kumquat.

Images: CC BY-NC-ND 2.0: Jan Friedrich
Pixabay: Deborah Jackson, Hans Braxmeier, Jacqueline Macou, Nicola Giordano
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  • Michele Ruocco wrote on 3 October 2020 at 1 h 59 min

    My 20year old potted cumquat was neglected for 6 months by tenants and nearly dead when we returned to our home. We were able to save it, but now there is only one small branch (which I think comes from the grafted part) bearing 3 fruit and the rest of the tree has reverted to something else with thorns and a large leaf. Any suggestions?

    • Gaspard wrote on 5 October 2020 at 11 h 52 min

      Hi Michele, lucky you got back in time! What you’ll need to do is prune off the thorny growth that clearly has different leaves. It comes from the rootstock, which is usually a very different plant from the kumquat graft that’s above it. If you let those branches grow, you won’t get any interesting fruits off it. This is because the rootstock is chosen for the strength and resilience of its roots, and not at all for the quality of the fruits. It’s sure to be a citrus, but it might not even be a kumquat.

      Another bad side effect of letting those rootstock shoots grow is that your grafted kumquat branch will actually die off! The roots will always favor their own shoots over grafted ones. You can try to identify the graft joint: anything below it will be rootstock shoots, and above it will be kumquat.

      So to sum it all up, snip the rootstock shoots off as they appear. Since only one grafted branch survived, you’ll have to prune it so that it can branch out. If you wand to speed its growth, remove the three fruits, so that energy and sap is diverted to the leaf buds.