Trifoliate orange

Trifoliate orange: how do you recognise it?

Habit

Dense, upright to rounded shrub, 2–3 m tall and 2–2.5 m wide, with angular green twigs.

Leaves

Trifoliate, with three glossy leaflets; they appear during or after flowering and turn yellow in autumn.

Thorns

Green, stiff and very sharp, up to 5 cm long, at every leaf joint.

Flowers

White, 3–5 cm across, with five petals, sweetly scented; in April–May on bare twigs.

Fruit

Round, 3–5 cm, green at first, then yellow and downy in September–October; many pips, little juice, bitter and sour.

Flowering: April–May · Plants: March–April and October–November · Pruning: June

Why grow it?

• Scented white blossom in April–May on bare green twigs.
• Bees flock to the early flowers.
• The green twigs and thorns give colour and structure even in winter.
• An impenetrable hedge that keeps unwanted visitors out.
• Yellow autumn colour and decorative yellow fruits.
• A citrus relative that can stay outdoors all year in Belgium.

Trifoliate orange: where does it grow best?

• Full sun, for the best flowering and the most fruit.
• Any well-drained garden soil: sand, loam or clay, acid to chalky.
• Normally moist; it dislikes soil that stays wet in winter.
• As a specimen allow 2.5 m; for a hedge plant 50–60 cm apart. Keep it away from paths and play areas.

Light

Sun

Soil type

Sand, loam or clay

Acidity

Not fussy

Moisture

Normal

Size

3 m tall, 2.5 m wide

Hardiness

Hardy (to -20 °C)

Goes well with

• Hawthorn: A native thorny shrub for a mixed, impenetrable hedge.
• Holly: Evergreen and prickly, for a hedge that stays dense in winter.
• Blackthorn: White blossom in March–April, just before the Poncirus, and thorny too.
• Lavender: Fragrant and sun-loving, as a low edging at a safe distance from the thorns.

Trifoliate orange: when and how to plant it?

Plant in March–April and October–November.

1. Plant in March–April or October–November, when the soil is neither frozen nor waterlogged.
2. Wear thick gloves and long sleeves: the thorns go through thin fabric.
3. Dig a hole twice as wide as the root ball and mix in a little compost.
4. Set the plant at the same depth as in the pot; for a hedge, space the plants 50–60 cm apart.
5. Water in well straight away and regularly in dry weather during the first year.
6. Mulch around the base: you will have less weeding to do between the thorns.

Care

Watering

In dry weather during the first year. Once established it copes, except in long dry summers.

Feeding

In March a little compost or organic fertiliser; no more is needed.

Mulching

A layer of wood chips or leaf mould keeps weeds down, as weeding between the thorns is no fun.

Fruit

Leave them on as decoration or pick them up when they fall; they are not for eating as they are.

Prunings

Clear up twigs straight away: even dry, the thorns stay sharp for a long time in the lawn and on the compost heap.

Tip: Plant it where you can smell it in April but will not brush past it: so not beside a path, terrace or play area. Always wear thick gloves when working on it.

Trifoliate orange: when to prune it?

Pruning months: June.

When: Prune after flowering, in June. It flowers on the previous year’s wood, so spring pruning costs flowers.

How:

• As a hedge: in June, trim the new growth back to the desired shape.
• As a shrub: only remove dead, crossing or overlong shoots back to a side branch.
• Use long-handled loppers or hedge shears and wear thick gloves, safety glasses and long sleeves.
• Clear up the prunings at once and never leave them where you work with bare hands.

Caution: The thorns are hard and razor-sharp and can cause deep puncture wounds. Never prune without protection.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Seed

In October take the pips from ripe fruits, rinse them and sow them straight away in a pot, as they dry out quickly. Most seedlings closely resemble the parent.

Cuttings

In July take semi-ripe cuttings of 10–15 cm and insert them in moist cutting compost under plastic. Rooting is slow.

Trifoliate orange: how does it get through the winter?

Hardy to −20 °C.

• Hardy to about −20 °C: in Belgium it can simply stay outdoors.
• Give young plants a layer of mulch around the base in their first winter.
• The twigs stay green in winter and bring colour to a bare garden.
• Late frost can damage the blossom or young leaves; the plant itself recovers.

Diseases and pests

• Frosted blossom: Brown flowers after a late frost. Nothing can be done; it will flower again next year. Avoid planting it in a frost pocket.
• Few fruits: In shade or after a cold spring it sets little fruit. A warm, sunny spot helps.
• Aphids: On young leaves in spring. Hose them off; ladybirds also eat them.
• Scale insects: Small brown shields on the twigs. Brush them off with a soft brush, wearing gloves.

Through the year

• March: Plant. Add compost.
• April: Flowering: scented white flowers on bare twigs. Plant.
• May: Last flowers; the leaves appear.
• June: Prune the hedge or shrub after flowering.
• July: Take semi-ripe cuttings. Water in dry spells.
• September: The small fruits turn yellow.
• October: Yellow autumn colour. Pick up ripe fruits and sow the pips. Plant.
• November: Plant. Mulch around young plants.
• December: Green twigs and thorns decorate the bare garden.

Good for wildlife

Bees

Nectar and pollen for honeybees and wild bees.

Did you know?

• Poncirus is used worldwide as a rootstock for lemon and orange trees, because it is hardy and resists several diseases well.
• Unlike other citrus, it has trifoliate leaves that fall in autumn.
• Long known as Poncirus trifoliata, it is now often placed by botanists in the genus Citrus.