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Citrus trifoliata

trifoliate orange

Rutaceae Northern China and Korea

Attracts Pollinators Attracts Butterflies Fragrant (moderate)Container Friendly

SunFull Sun – Part Shade

WaterMedium

HardinessZones 5–9

Overview

Citrus trifoliata is a deciduous, densely thorny shrub or small tree growing 8-20 feet (2.4-6 m) tall, with stiff, angled green stems armed with stout flattened spines up to 2 inches (5 cm) long. The leaves are trifoliate, with three leaflets 1-2 inches (2.5-5 cm) long on a winged stalk, turning yellow before dropping in autumn. White, fragrant flowers 1.5-2 inches (4-5 cm) across open in spring, before or with the new leaves, each with five petals. The fruit is a round, downy, yellow citrus 1.5-2 inches (4-5 cm) wide, aromatic but sour and bitter, with many seeds and dry pulp. The green stems stay photosynthetic and green through winter after the leaves fall. It tolerates cold to around USDA zone 5, well below the limit of edible citrus, and is grown as a grafting rootstock and a barrier hedge. The dense spines make it impenetrable but hazardous near paths. It seeds freely and is invasive in parts of the southeastern United States.

Native Range

Citrus trifoliata is native to northern China and Korea. It has been widely planted elsewhere as a rootstock and hedge and has naturalized in the southeastern United States, where it spreads into woodlands and field edges.

Suggested Uses

Planted as a barrier or security hedge, in informal screens, and as a cold-hardy citrus rootstock. It is also grown as a curiosity for its green stems and aromatic fruit. The spring flowers draw bees, and birds shelter in the thorny growth.

How to Identify

Identify Citrus trifoliata by its green, spiny stems, three-part leaves on winged stalks, and downy yellow citrus fruit 1.5-2 inches (4-5 cm) wide. The stout, flattened thorns and trifoliate, deciduous leaves separate it from evergreen citrus, which have single leaves. In winter the bare stems remain green and identify the plant among leafless shrubs.

Appearance

Size & Dimensions

Height8' - 20'

Width/Spread6' - 15'

Reaches mature size in approximately 8 years

Colors

Flower Colors

white

Foliage Colors

green

Fall Foliage Colors

yellow

Bloom Information

Bloom Period

~2 weeks

Spring

White, fragrant flowers open in early to mid spring, generally March to April, before or as the leaves emerge. Bloom lasts one to two weeks. The flowers are followed by green fruit that ripens to downy yellow by autumn.

Detailed Descriptions

Foliage Description

green

Growing Conditions

Sun Requirements

SunFull Sun SunPartial Shade

Requires 6-12 hours of direct sunlight daily

• Full Sun: 6+ hours of direct sunlight

• Partial Shade: 3-6 hours of direct sunlight

• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range5.5 - 6.5(Neutral)

357912

Soil Types

loam sand clay

Drainagewell drained

Water & Climate

Water Needs

Medium

Frost Tolerance

hardy

Time to Maturity

5-10 years

Care & Maintenance

Care Guide

Grow Citrus trifoliata in full sun to part shade in moist, well-drained, slightly acidic soil with a pH from 5.5 to 6.5. It tolerates a range of soils and cold to about USDA zone 5, well below the limit of edible citrus. The plant grows at a moderate rate and forms a dense, spiny thicket that makes a stock-proof hedge. Its sharp spines call for placement away from walkways and play areas. It can be grown from seed or used as a cold-hardy rootstock for grafted citrus. In mild regions it self-sows and can spread beyond the planting.

Pruning

Prune in late winter while dormant to shape the plant or to maintain a hedge, cutting back the previous season's growth. The dense, thorny stems tolerate hard shearing. Working around the spines requires caution.

Pruning Schedule

winter