How to grow Kumquat

Citrus japonica · cumquat

Kumquat (Citrus japonica) — the kumquat is a small evergreen citrus tree from southern China with olive-sized orange fruit that is eaten whole, sweet peel and tart flesh together. It is one of the most cold-hardy citrus and, grafted on a dwarfing rootstock, one of the easiest to keep in a pot that winters indoors or in a greenhouse. Grafted trees give their first real crop in the third year.

Checked against sources: October 3, 2026

Quick facts

Type	Fruit tree
Family	Rutaceae
Light	Full sun
Soil pH	5.5–6.5
Frost	does not tolerate frost
First harvest after planting	about 3 years
Where it grows	Greenhouse, Open ground, At home

When to plant

Planted as a young plant from a nursery while it is dormant — in early spring before the buds open, or in autumn after leaf fall.

Harvest from November to March (northern hemisphere).

Frost dates · When to plant

Care

Greenhouse

Stage	Watering	Temperature	Feeding
Growth	every 7 days	18…29 °C	nitrogen, at the start of the stage; nitrogen, 42 days into the stage
Flowering	every 7 days	18…29 °C	nitrogen, at the start of the stage
Fruiting	every 7 days	18…29 °C	nitrogen, at the start of the stage; nitrogen, 42 days into the stage; nitrogen, 84 days into the stage
Harvest	every 14 days	7…18 °C	balanced (NPK), at the start of the stage
Winter rest	every 14 days	7…18 °C	balanced (NPK), at the start of the stage; balanced (NPK), 60 days into the stage

Open ground

Stage	Watering	Temperature	Feeding
Growth	every 7 days	—	organic, at the start of the stage
Flowering	every 7 days	—	organic, at the start of the stage
Fruiting	every 7 days	—	—
Harvest	every 14 days	—	—
Winter rest	—	—	—

At home

Stage	Watering	Temperature	Feeding
Growth	every 7 days	18…29 °C	nitrogen, at the start of the stage; nitrogen, 42 days into the stage
Flowering	every 7 days	18…29 °C	nitrogen, at the start of the stage
Fruiting	every 7 days	18…29 °C	nitrogen, at the start of the stage; nitrogen, 42 days into the stage; nitrogen, 84 days into the stage
Harvest	every 14 days	13…18 °C	balanced (NPK), at the start of the stage
Winter rest	every 14 days	13…18 °C	balanced (NPK), at the start of the stage; balanced (NPK), 60 days into the stage

Growing notes

Light

Give it the sunniest spot you have, ideally at least 8 hours of sun, such as a south-facing window or a bright conservatory; in summer it can stand outdoors in a sunny, sheltered place.

Soil

Use a free-draining, slightly acidic mix (pH 5.5–6.5) in a pot with drainage holes. Kumquats hate waterlogging, so never leave the pot standing in water.

Care

Water when the top 5–7 cm of the mix feel dry, which in hot weather can be almost every day; in winter let the surface dry partly and err on the dry side. From late March to October feed a high-nitrogen citrus fertiliser, and from November switch to a balanced winter citrus feed. Keep it at about 18–29 °C while growing and cooler in winter, at 13–18 °C indoors or no lower than 7 °C in a greenhouse; harden it off gradually before moving it outside in late spring. Kumquats rest from autumn to spring and flower in early summer, later than other citrus; they are self-fertile, but a soft brush helps indoors. Do not let a potted tree become pot-bound, and prune lightly in early spring. Remove any fruit in the first two years so the young tree builds roots and branches.

How to tell it is ripe

The fruit has turned fully orange all over, with no green left.
Kumquats are at their best in late winter and early spring.
The tree is the best store, so ripe fruit can hang there until you need it.
Taste one before picking more; citrus fruit does not get sweeter once picked.
Cut each fruit with secateurs, keeping a short piece of stalk (or a couple of leaves), because pulling it off can tear the peel.

Pests and diseases of Kumquat

Sources

Figures checked against these sources.