Citrus japonica (Kumquat)

Kumquat’s subtropical Chinese home

Kumquat is native to southeastern China, including Hainan, and has been cultivated in East Asia for centuries. It later spread widely as both an ornamental and edible citrus.

Its native region has a subtropical climate with clear seasonal temperature changes.

Growing Kumquat in a container

• Cooler conditions: Kumquat can stay in bright, cool, frost-free conditions when shoot growth has paused. Water and feed less while demand is low. If you later move it to warmer conditions, make the change gradually.
• Light and humidity: Give very strong light and direct sun to keep the twiggy crown dense and support flowering and fruit colour. Indoors, keep humidity moderate and place the foliage away from dry air from heaters.
• Watering: Rewater after the surface dries and the centre is lightly moist. A fruiting plant should be watered before the root ball dries throughout; in cooler conditions, allow a little more drying between waterings.
• Mix and repotting: Use an open citrus mix that drains freely and still holds some moisture. When roots are crowded, move to the next pot size. If an older mix has become dense, refresh it even if the plant can stay in the same container.
• Feeding and maintenance: Feed according to a complete citrus-fertiliser label while the plant is active. Kumquat needs little pruning beyond shortening shoots that break the outline, and fruit only needs support or thinning when a young branch starts to bow.

Kumquat stress and pest problems

• Green leaves fall after Kumquat comes indoors: A quick move from cool bright conditions to a warmer, darker room can trigger leaf loss. Keep light, temperature and root moisture steady and base watering on the mix’s actual drying speed after leaf fall.
• Fruit drops while the potting mix is very dry: Developing fruit raises water demand, and severe drought can increase crop loss. Rehydrate the mix evenly, allow full drainage and maintain a steadier moisture cycle through fruit development.
• Brown bumps, honeydew or black surface growth appears: Scale insects often settle on woody stems and leaf undersides. Isolate Kumquat, remove visible insects and clean sticky residue. For an active scale infestation, use only a product labelled for scale and the plant, repeating it solely as the label directs. The scale guide can help confirm active insects.
• Leaves yellow and the pot remains wet for a long time: Cool, saturated potting mix can damage fine roots. Let the mix dry enough for air to return around the roots and inspect for soft dark tissue if the decline continues; use the root-rot guide if decay is present.

If the cause is still unclear, send us clear photos of the whole plant, the affected area and the potting mix so we can help you narrow it down.

Keep Citrus japonica (Kumquat) away from pets

• The fruit flesh is edible, while leaves, peel and other plant material can irritate cats and dogs.
• These parts contain essential oils and psoralens that may cause vomiting, stomach pain, unusual tiredness or skin irritation.
• Contact a veterinarian if a pet chews the plant or develops symptoms. Seek medical advice if a person becomes unwell after exposure.

When was Citrus japonica first published, and what does it mean?

Citrus is the classical Latin name used for citron and related citrus plants. The epithet japonica means “of Japan”.

Carl Linnaeus established the genus Citrus in 1753 in Species Plantarum, page 782.

Carl Peter Thunberg first described Citrus japonica in 1780 in Nova Acta Regiae Societatis Scientiarum Upsaliensis, series 2, volume 3, page 208.