Finger lime (Citrus australasica)

They have become a very popular backyard citrus as a bushtucker plant for gardens or large containers. This species is native to Australia, where it grows naturally as an understorey plant in subtropical and coast rainforests along the east coast. It is one of six species of citrus that are native to Australia.

The shrubby plant produces small, finger-like fruit (6-12cm in length) that is filled with tangy beads of flesh that resemble caviar. The fruit has a strong citrus scent but is not as juicy as a non-native lime or lemon but each bead pops in the mouth with a tangy flavour.

A recent breeding program has developed varieties with differently coloured skin and pulp. The species has green skinned fruit, but the varieties may have red, orange, yellow or apricot coloured skin, while the pulp can be clear, green, pink or dark red. Seediness also varies between few and lots of seeds.

If you’re interested in this very different and unique fruit, check out varieties in your local hardware or garden centre to suit your location and climate. Look out for named varieties including:

• ‘Pink Ice’ (pink skinned) should fruit well within three years of planting (seedling grown plants can take many years to fruit).
• ‘Red Champagne’ (red skinned) is a popular variety that grows to around 2 metres. It produces fruit from March to May with a mild and subtle taste.
• ‘Green Crystal’ (green skinned) is a highly acidic fruit, much like a regular lime. Fruiting from March to early June it will grow to around 1.7 metres, so it’s ideal for pots.
• ‘Yellow’ (green skinned) has subtle lemon caviar flavoured fruit which is ideal for the citrus lover. It has long branches adorned with green fruit.
• ‘Emma’ (black to maroon skin) which becomes red when it is ripe. Producing fruit from mid-February to April and reaching a height of 1.7 metres makes it ideal for a large container.

Flowering and fruiting times can vary but plants generally flower from winter to spring with fruit forming from summer to autumn. Pick fruit when ripe for best results as they don’t ripen off the plant. They are used for their tangy burst of juice, decorative flesh or in most other ways a traditional lime or lemon would be used. They partner well with seafood such as oysters.

Finger limes can be planted at any time (but avoid extremely hot or cold conditions). To reduce transplant stress water in with Seasol when planting.

The trees are compact usually reaching around 2-6m high and 2-3m wide, but can be pruned to size. They are evergreen with sharp thorns. They are an ideal choice for a containerised fruit tree for a small garden or sunny balcony, but can also be grown as a garden plant or as a dense hedge. Its dense, spiny growth makes it a good habitat plant.

Growing conditions

Aspect Finger limes need a bright, sunny location with sun from the morning onwards, but tolerate dappled light. They can tolerate afternoon shade, especially in hot climates. Protection from cold conditions is vital. In cooler regions, a north-facing brick wall is ideal, as a warm microclimate.

Soil They grow in a wide range of soils but require excellent drainage. Before planting, add homemade compost and organic matter and/or Seasol Super Compost. In areas with poor drainage, grow in raised garden beds (raised at least 30cm) or in large containers using a premium potting mix such as Seasol Advanced Potting Mix.

Climate Finger limes grow in all temperate to subtropical climates, however in cold areas, they need protection from cold, drying winds and frosts, especially over winter.

General care

Watering Adequate and regular water is critical for fruit formation and development. Lack of water can lead to loss of flowers or fruit. Deep water at least weekly especially when plants are in new growth, flowering (usually occurs in autumn) or fruiting (late autumn to summer). Water more frequently if plants are in hot, dry or exposed conditions or if they are growing in containers. Regularly apply Seasol every two to four weeks for healthy growth, good root development and to reduce stresses from pot life, frost and heat.

Feeding and mulching Feed regularly with a native plant food or a low phosphorus fertiliser such as Seasol plus Nutrients All Purpose including Natives. Avoid feeding while trees are flowering and fruit is forming. Plants in containers can be liquid fed with PowerFeed All Purpose including Natives fortnightly to monthly while they are growing (late spring to autumn).

Protect the area around the base of the tree with a 5-7cm layer of coarse organic mulch such as leaf litter, straw or pine bark, which helps keep the soil evenly moist and weed-free.

Pruning Finger limes fruit without regular pruning, however, it is necessary to remove dead wood. Regular light pruning helps shape the plant. Do not hard prune. Fruit thinning can be carried out if crops are very heavy.

Watch out The main pests that attack citrus also attack native finger limes. Pests include aphids on new growth, scale on leaves and stems and citrus leaf miner, which causes silvery trails in new growth. Bugs including spined citrus bug attack developing fruit. These problems can be controlled with applications of organic EarthCare White Oil insect spray. Do not spray when beneficial bees or insects are around.