Name: finger lime, caviar lime (Citrus australasica).
Height: up to 6m.
Plant type: large shrub or small tree.
Climate: warm temperate, sub-tropical and tropical.
Soil: moist, well-drained, and slightly acidic (pH 5–6.5).
Position: full sun to part shade with protection from strong winds.
Foliage: small, glossy green and strongly citrus-scented.
Flowering and fruiting: white or pale-pink flowers from late summer into autumn, followed by elongated, finger-like fruit that can be green, yellow, pale pink or bright red. The fruit are filled with tiny caviar-like pearls (vesicles), which explode with tangy citrus juice.
Feeding: feed regularly with a complete citrus fertiliser.
Watering: water regularly to keep soil moist.
Native finger lime grows into a large shrub or small tree up to 6m tall, but can be kept compact with regular trimming. Its dense canopy is made up of thorny branches and tiny, glossy green leaves. Small white or pale-pink flowers appear in late summer and autumn, and once pollinated, develop into stubby, finger-like fruit that can be green, yellow, pink or bright red, depending on the cultivar. The fruit is filled with juicy beads, affectionately called "lime caviar", and burst with luscious tangy flavour when eaten or squeezed.
Seedling-grown trees are slow growing and can take up to 15 years to bear fruit. Grafted varieties typically start bearing fruit after three years, and are fully bearing after six years.
The dense canopy of finger limes makes them a great candidate for an informal hedge – the birds will love it, too, as it provides shelter and protection when nesting. Otherwise, grow it as a large shrub or small tree in the garden or a large pot.
Use the juicy beads to garnish seafood, dress salads or flavour drinks and sauces. The fruit can also be used in desserts or turned into jam. Freeze any excess for use later.
Choose a spot in full sun or part shade with well-drained soil. In hotter climates, planting in part or filtered shade will help reduce the risk of sunburn. Enrich the soil by digging in compost and well-rotted manure. If growing in a pot, choose a pot at least 40cm wide and fill with premium quality potting mix. Dig a hole twice as wide and to the same depth as the existing root ball. Remove the plant from its pot, loosen the root ball and place in the centre of the planting hole. Backfill, firm the soil and water in well.
Apply a layer of organic mulch around the base of the plant to help conserve soil moisture and suppress weeds. Keep the mulch at least 10cm away from the trunk to prevent collar rot.
Like any other fruiting citrus, finger lime requires regular watering and fertilising to grow into a healthy, productive tree. Water regularly after planting. Once established, water once or twice a week, or more during hot dry weather. Water thoroughly when flowering and fruiting, and top up the mulch as needed to help conserve soil moisture.
Feed once every three months with a complete citrus fertiliser. When feeding during the fruiting season, it is recommended to wait until fruits are longer than 1cm before feeding, otherwise it may cause premature fruit drop.
When young, prune lightly after flowering to encourage an open shape with 4–6 main branches. Remove suckers or any growth below the graft union, as well as any vigorous water shoots. Once fruiting, lightly prune after harvest to open the canopy, remove diseased and dead wood, and any criss-crossing branches.
Finger lime is susceptible to most common citrus pests, including scale, bronze orange bug, aphids, mealybugs, citrus leafminer and caterpillars. All can be treated with an organic insecticide as required.
Melanose is a fungal disease that can affect the stems, foliage and fruit. It causes dark brown to black spots to form on plant parts, spoiling fruit and decreasing the overall health and vigour of the citrus tree. Regular pruning to remove dead wood will help prevent the disease.
Grafted varieties will be ready to harvest after three years, but seedling trees can take up to 15 years to fruit. To harvest, pick when the fruit is firm and detaches easily. Do not pick when under-ripe as fruit will not continue to ripen once removed. If unsure, pick a few and taste the pulp – unripe fruit will taste bitter. When cutting, avoid getting the oil from the rind onto the fruit as it can affect the flavour.
Finger limes can be propagated via seeds, cuttings and bud grafts. Seeds may not be true to type, so are often avoided. Cuttings are true to type but can take up to 15 years to fruit, unless grafted onto a suitable rootstock (commonly Citrus trifoliata). For best results, buy grafted varieties in store.
After applying fertiliser, delay harvesting for a few days and rinse well before cooking and eating. If using products to deal with pests, diseases or weeds, always read the label, follow the instructions carefully and wear suitable protective equipment. Store all garden chemicals out of the reach of children and pets.
Native lemon grass: a handsome tufted grass with lemon-scented foliage.
Midyim berry: an attractive low-growing shrub with small white, purple-speckled berries.
Red back ginger: a native ginger with mild flavoured rhizomes and lemony-ginger berries.
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