Kumquat

Kumquat: how do you recognise it?

Habit

Compact, densely branched shrub or small tree; in a pot 1–2 m tall and about 1 m wide.

Leaves

Lance-shaped, 4–9 cm, glossy dark green and leathery; evergreen.

Flower

Small white five-petalled flowers, single or in small groups in the leaf axils, in June–August.

Scent

Sweet and typical of citrus, like orange blossom.

Fruit

Oval or round, 2–4 cm, golden orange when ripe from late autumn into winter; sweet peel and sour flesh.

Roots

Fine and fairly shallow; sensitive to waterlogging and hard water.

Flowering: June–August · Harvest and fruit: December–March · Plants: April–May · Pruning: March

Why grow it?

• Glossy green leaves all year round on the patio or in the conservatory.
• Fragrant white flowers in summer.
• Orange fruits in winter, when colour is scarce.
• The fruits are eaten skin and all, or made into marmalade or candied fruit.
• Compact, slow-growing and self-fertile: ideal for a large pot.

Kumquat: where does it grow best?

• As sunny as possible: outdoors on a warm, sheltered patio in summer.
• Open, free-draining potting compost, slightly acid to neutral, with some sand or grit.
• Evenly moist, never sodden; do not leave water standing in the saucer.
• In winter, bright and frost-free at 5–10 °C, for example in an unheated greenhouse or a cool, light room.

Light

Sun

Soil type

Sand or loam

Acidity

Acid or neutral

Moisture

Normal

Size

2 m tall, 1 m wide

Hardiness

Half hardy (to -5 °C): protect it in harsh winters

Goes well with

• Olive tree: A Mediterranean pot plant that likes the same sunny, warm spot.
• Bay laurel: Evergreen and aromatic, in a pot beside the kumquat.
• Lavender: Silvery leaves and purple flowers for the same sunny spot.
• Rosemary: A fragrant kitchen herb in a pot alongside.

Kumquat: when and how to plant it?

Plant in April–May.

1. Pot up or repot in April–May, as new growth begins.
2. Choose a pot only 3–5 cm wider than the old one, with a drainage hole and a layer of gravel or clay pebbles in the bottom.
3. Use citrus compost, or ordinary potting compost mixed with a third of sand or fine grit.
4. Set the plant at the same level as before: the base of the trunk must not be buried.
5. Water well and let the excess drain away.
6. Only put it outside after mid-May, in partial shade for the first week so the leaves do not scorch.

Care

Watering

Water when the top 2–3 cm feel dry, and then thoroughly. Use rainwater where possible: hard tap water causes yellow leaves.

Feeding

From March to September, citrus fertiliser every 1–2 weeks; none in winter.

Indoors and out

Outside in the sun from mid-May to October; bring it in before the first night frost.

Harvesting

Pick the fruits when they are fully orange; they hang on the plant for a long time. Eat them fresh or make marmalade or candied fruit.

Repotting

Every 2–3 years in spring. For large, older plants, just replace the top layer of compost.

Tip: Overwinter it in a bright, cool spot at 5–10 °C and water with rainwater: it will keep its leaves and the fruits will colour a fine orange. Eat them skin and all, because the peel is the sweet part.

Kumquat: when to prune it?

Pruning months: March.

When: Prune lightly in March, after harvesting and before new growth starts.

How:

• Cut out dead, weak and crossing twigs.
• Shorten overlong shoots to just above a leaf to keep the crown compact and nicely rounded.
• Remove any shoots growing from the rootstock below the graft.
• Do not prune too hard: a lightly pruned plant flowers and fruits best.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Cuttings

In June–July: 10–15 cm semi-ripe cuttings in moist cutting compost, under plastic, in a warm place at 20–25 °C. Rooting takes several weeks to months.

Seed

Pips from a ripe fruit germinate fairly easily, but seedlings grow slowly and take many years to fruit. Nurseries therefore graft onto a rootstock.

Kumquat: how does it get through the winter?

Hardy to −5 °C: protect in harsh winters.

• It tolerates brief, light frost to about −5 °C, but in a pot the roots soon freeze: bring it in during October.
• Overwinter in good light and cool conditions at 5–10 °C: in a warm living room it often drops its leaves.
• In winter give little water, only when the root ball is almost dry, and no feed.
• In spring, move it outside gradually, first into partial shade.

Diseases and pests

• Scale insects: Brown bumps on stems and leaves, with sticky leaves and sometimes black sooty mould. Wipe them off with a cloth or cotton bud and rinse the plant.
• Red spider mite: Fine webbing and speckled leaves in warm, dry indoor air. Move the plant somewhere cooler and spray the leaves with water.
• Yellow leaves: Caused by hard water, waterlogging or cold roots. Water with rainwater, ensure good drainage and use citrus fertiliser.
• Leaf drop: Caused by a sudden move to a dark, warm place or by drying out. Overwinter in a bright, cool spot and keep the root ball lightly moist.

Through the year

• January: Harvest the fruits. Bright and cool, little water.
• February: Harvest. Watch for scale insects.
• March: Light pruning. Start feeding.
• April: Repot if needed. Water more.
• May: After mid-May, move outside gradually.
• June: Flowering. Regular water and feed.
• July: Flowering. Take cuttings.
• August: Flowering. The first fruits set.
• September: Last feed of the year.
• October: Bring in before the first frost.
• November: The fruits turn orange. Little water.
• December: First fruits to harvest.

Edible and useful

Fruit (December–March)

The kumquat bears small, oval, orange fruits in winter, from December to March. Pick them when they are fully orange. They are eaten whole, skin and all: the peel is sweet, the flesh sour. Lovely fresh, candied, in marmalade, in a salad or with duck.

Storing

Kumquats keep for two weeks in the fridge. Candied or as marmalade they keep for months.

Caution: Only eat fruit from a plant that has not been sprayed: wait a year before eating fruit from a newly bought plant. Spit out the pips. The tree tolerates a few degrees of frost but in our climate is best overwintered somewhere cool and light indoors.

Eating and using is at your own risk: see the terms of use.

Recipes

• Candied kumquats (Other · ± 2 jars · 45 min)

Did you know?

• The name kumquat comes from Cantonese and means ‘golden orange’.
• Around Chinese New Year, potted kumquat trees are often given as gifts or placed in the home in China and Vietnam as a symbol of prosperity.
• It used to have its own genus, Fortunella, named after the Scottish plant hunter Robert Fortune, who brought it to Europe in the 19th century.