Australian Finger Lime

Citrus australasica is endemic to the coastal border region of Queensland and New South Wales in Australia. Its evolutionary lineage is part of the ancient Gondwanan citrus radiation, with the species having diversified in the isolated, refugial rainforest habitats of the Australian continent over millions of years. Long utilized as a bush food by Indigenous Australians, it has gained international culinary prominence only in recent decades.

Australian Finger Lime is a woody shrub or small tree, typically reaching 2 to 7 meters in height.

Branches & Thorns:
• Branches are densely armed with stout, sharp axillary thorns
• Thorns can be up to 2.5 cm long

Leaves:
• Leaves are small, ovate to elliptic, measuring 1 to 5 cm long
• Glossy dark green on the upper surface, paler beneath
• Aromatic when crushed, with oil glands visible as tiny dots against light

Flowers:
• Borne singly or in small clusters in the leaf axils
• Petals are white to pale pink, typically 6 to 9 mm long
• Sweetly fragrant

Fruit:
• A botanical berry (hesperidium), cylindrical and finger-shaped, 4 to 12 cm long and 1.5 to 3 cm in diameter
• Skin is thin, ranging in color from greenish-yellow and yellow to deep red, purple, or nearly black
• The pulp consists of discrete, firm, spherical vesicles that separate easily
• Vesicles range from clear to pale green, yellow, pink, or red

In its natural habitat, Citrus australasica grows as an understorey plant in lowland subtropical rainforest and wet sclerophyll forest, typically at altitudes from sea level to 600 meters. It prefers sheltered positions with dappled light and well-drained, fertile soils. The flowers are pollinated by insects, and the fruits are dispersed by native animals. The species demonstrates a degree of frost sensitivity, reflecting its evolution in relatively frost-free coastal environments.

Cultivation of the Australian Finger Lime has expanded significantly as a specialty fruit crop. While it can be challenging to grow outside its native climate, it adapts well to container culture.

Light:
• Prefers full sun to partial shade; in hot climates, protection from intense afternoon sun is beneficial

Soil:
• Requires well-draining, slightly acidic soil (pH 5.0–6.5)
• Performs well in high-quality potting mix if grown in containers

Watering:
• Needs consistent moisture, especially during flowering and fruit set, but is intolerant of waterlogged conditions

Temperature:
• Grows best in warm temperate to subtropical climates
• Tolerates light, brief frosts once established, but young plants require protection

Pruning:
• Prune lightly after harvest to maintain shape and remove any dead or crossing branches, taking care with the sharp thorns

Propagation:
• Commercially propagated by grafting onto compatible rootstocks to ensure fruit quality and disease resistance; can also be grown from seed, though seedlings may exhibit significant variation

Pests & Diseases:
• Susceptible to common citrus pests such as scale insects, aphids, and citrus leafminer
• Good air circulation helps prevent fungal issues