Kumquat

Sun

Full sun; a warm, sheltered position gives the best flowering and fruit ripening.

Water

Water deeply when the upper soil begins to dry, then allow excess water to drain. Containers need regular checks in summer and much less water in cool winter conditions.

Soil

Fertile, well-drained, slightly acidic soil. For containers, use a free-draining citrus potting mix and a pot with drainage holes.

Height

8-15 ft (2.4-4.6 m); usually smaller in containers

Spread

6-10 ft (1.8-3 m)

Flowers

Small, fragrant white flowers, mainly in summer; additional flushes may occur in warm climates.

Foliage

Evergreen. Small, glossy, dark green leaves on densely branched shoots; some plants have thorns.

Growth

Slow to moderate

Care needed

Medium

• Pollinators
• Heat tolerant
• Low allergen
• Fragrant
• Edible

Northern hemisphere months. In Australia, shift them by six.

Difficulty

Moderate

Toughness

Fairly tough

Pick your zone, country, light and whether you have pets.

1. Planting day

   7 ft (2 m)

2. After 1 year

   7 ft (2.1 m)

3. After 2 years

   7 ft (2.1 m)

4. After 3 years

   7 ft (2.2 m)

5. After 5 years

   8 ft (2.3 m)

About 26 years to full size.

From a typical nursery size, at an average rate for this kind of plant. A rule of thumb, not a forecast.

Cats and dogs

Mildly toxic: may upset a stomach

Growth rate

Slow

• Water the root zone thoroughly without leaving the pot standing in water.
• Apply citrus fertiliser at the label rate during active spring and summer growth; do not feed a dormant plant.
• Mulch outdoor trees, keeping mulch clear of the trunk and graft union.
• Move container plants into bright, cool, frost-free shelter before autumn frosts; avoid hot, dry rooms.
• Remove shoots arising below the graft union.

Pruning. Prune lightly after harvesting and before the main spring growth, removing dead, crossing or crowded shoots. Keep shaping modest because heavy pruning removes future flowering wood.

Pick firm, fully orange kumquats when the peel tastes sweet and the flesh is juicy; snip them off with secateurs, as they will not ripen further after picking. Harvest is usually winter into spring in the US, UK and Canada, where cold-climate plants need frost-free shelter, and autumn through winter, sometimes into spring, in Australia.

Spring

Begin feeding as new growth starts; repot only when roots have filled the container.

Late spring

After frost risk has passed, gradually acclimatise sheltered plants to outdoor sun.

Summer

Check container moisture frequently and inspect new growth for scale insects, aphids and leafminer damage.

Autumn

Stop feeding as growth slows and arrange bright, frost-free shelter where winters are cold.

Winter

Keep sheltered plants cool and bright, watering sparingly without letting the root ball dry completely.

Winter to spring

Harvest fully coloured fruit when it tastes ripe; exact timing varies with cultivar and climate.

• Grow in a large container beside a sunny patio or courtyard seating area, where the flowers' scent can be appreciated.
• Use matching potted trees to frame a doorway, moving them under cover for winter where necessary.
• Plant as a compact evergreen specimen in a sheltered edible garden.
• Combine with low herbs or seasonal flowers around the outer edge of a sunny border, leaving the trunk base clear.

Garden styles it suits: Modern courtyard, Mediterranean, Potager (kitchen garden), Edible landscape, Small-space and Winter interest.

Plant it with: Chives, Nasturtiums and French marigolds.

Wildlife: The flowers attract bees and other pollinating insects. Kumquats are generally self-fertile, so one tree can fruit, although insects help move pollen.

• Scale insects and sooty mould: inspect stems and leaf undersides; remove small infestations by hand and use a labelled horticultural oil if needed.
• Spider mites indoors: look for fine webbing and stippled leaves; rinse foliage regularly and use a labelled treatment if the infestation persists.
• Citrus leafminer: larvae tunnel through young leaves; avoid excessive nitrogen and unnecessary pruning that encourages repeated soft growth, and retain healthy older foliage.
• Root rot and yellowing from poor drainage: keep drainage holes clear, empty saucers and allow the upper growing medium to dry slightly between waterings.

Ripe fruit, including the peel, is edible and is not known to be toxic to people. Citrus oils and other compounds in the leaves, stems and peel can cause digestive upset in cats, dogs and horses if eaten; skin irritation is also possible. Concentrated citrus oils pose a greater risk than incidental contact with the tree.

• Calamondin (Citrus × microcarpa)

  Usually has round, miniature orange-like fruit with very sour juice; kumquat fruit is often oval and is typically eaten whole for its sweet peel.

• Mandarin (Citrus reticulata)

  Has larger, often flattened fruit with loose peel that separates readily into segments; kumquats have much smaller fruit with peel closely attached to the flesh.

• Limequat (Citrus × floridana)

  This lime–kumquat hybrid usually ripens yellow rather than orange and has a sharper, lime-like flavour; fruit colour alone is unreliable before full ripeness.

Kumquat comes from a Cantonese name meaning 'golden orange', while japonica means 'Japanese', although the plant originated in China.

Propagation. Usually grafted or budded onto a suitable citrus rootstock to control size and improve performance in local soil conditions. Seed-grown plants may differ from the parent and take many years to fruit; cuttings can be difficult to establish.

Accepted botanical name

Citrus japonica

Native range

China Southeast and Hainan.

Measured

Average height 500 cm.

Sources: GBIF (CC BY 4.0) and Trefle (CC BY 4.0). The care and design notes are LandscapeGPT's own.