Australia is home to six species of native citrus, the most well-known of which is the finger lime (Citrus australasica, formerly known as Microcitrus australasica). Finger limes are an understory shrub, or tree, native to border ranges of southeast Queensland and northern NSW, that are part of the Barunggam, Wakka Wakka, Bundjalung and Gumbainggir lands.
Related: Buddha’s hand citrus
History
Finger limes have been a valuable food source to Indigenous Australians for thousands of years (gulalung is the Bundjalung language name for finger limes). The pearls were applied topically as an antiseptic and may accelerate wound healing.
Much of the finger lime population was destroyed due to land clearing for farming by early European settlers. Isolated pockets in subtropical rainforests and private land still remain.
Judy Viola of Judy Viola Citrus Nursery trialled 90 finger lime cultivars from 1989 and chose ten varieties. Eight finger limes are registered with the Australian Cultivar Registration Authority which vary in size and shape.
- Alstonville
- Blunobia Pink Crystal
- Byron Sunrise
- Jali Red
- D1
- Rainforest Pearl
- Pink Ice
- Durham’s Emerald
Judy pioneered the successful grafting of finger limes, which are typically grafted to Citrus trifoliata for its ability to resist Phytophthora root rot. Growing from seed is generally not recommended as they won’t always be true to type and take up to 15 years to mature. Commercial production of finger limes is mostly confined to northern NSW and southern Queensland.
Over the past decade, commercial interest in bush food has propelled finger lime into the spotlight with the fruit commanding a high market price. 50% of finger limes are exported to Europe and Asia where they are served in high-end establishments. If you are lucky enough to find finger limes for sale, prices start from $80 Australian dollars per kilogram.
Finger limes are able to hybridise with other citrus varieties and the CSIRO has produced three novel finger lime varieties suitable for commercial sale.
- Australian Blood Lime: Citrus australasica (finger lime) x Citrus × microcarpa (mandarin x cumquat)
- Australian Sunrise Lime: Citrus australasica var. sanguine (red finger lime) x Citrus × microcarpa (mandarin x cumquat)
- Australian Outback Lime: Also known as Australian Desert Lime, the Australian Outback Lime is a cultivar developed from a collection of native desert lime trees (Citrus glauca).
All three novel finger limes were granted Plant Breeders Rights in 2004 and licensed to four Australian nurseries.
Characteristics of Australian finger lime
These unique plants consist of thorny branches, with small, oval-shaped dark green leaves and long fruit which range in length from 3 to 10 cm. The fruit is filled with small translucent juice-filled vesicles commonly referred to as caviar or citrus pearls. Finger lime peel and pulp come in an assortment of colours including red, pink, champagne, yellow and green. Over 65 varieties of finger lime have been identified in the wild.
The flavour of finger limes is described as tart, tangy and citrus. The small juice-filled pearls burst in your mouth when you eat them, releasing their refreshing juice.
Finger limes have a delicate floral, citrusy, and slightly sweet aroma that is not as strong as other citrus varieties, but it can still be detected when the fruit is sliced open or its zest is grated.
How to grow finger limes
| Care requirements for finger limes |
| Light: Full sun to part shade, ideally at least six hours of direct sunlight per day. In hot and dry climates, they may benefit from some shade during the hottest part of the day |
| Watering: Regular watering to keep the soil moist but not waterlogged. Water deeply once a week, and more frequently in hot and dry weather |
| Time to fruit: 2-3 years depending on the variety |
| Fruit maturation/harvest: Autumn to winter |
| Soil type: Finger limes require a well-drained soil that is rich in organic matter and nutrients |
| Soil pH: Neutral (6.6-7.3pH) |
| Fertiliser: Every 3 months during the growing season |
Finger lime fruit is sometimes available at specialist greengrocers but is not generally available in supermarkets. Compared to other citrus varieties, finger lime is relatively expensive as they are a specialty product that is not grown commercially on a large scale. The fruit is very delicate and requires careful handling during harvesting. In addition, finger limes are highly valued in high-end restaurants, which further drives up the price.
Thankfully finger lime trees are sometimes available at Bunnings (for Australian readers) and some nurseries such as Daleys Fruit so you can grow your own supply.
Finger lime grows well in the ground or in pots, while its natural habitat is underneath the canopy of taller trees, it can tolerate light frosts, but will need protection from the strong summer sun. I find my finger limes are less tolerant of full sun than other citrus varieties and grow well in an east-facing position, where they receive afternoon sun.
Like all citrus varieties, finger limes prefer well-drained soil and a sheltered position away from strong winds which can damage the fruit as it rubs against the thorns. Plant on a mound in areas of high rainfall to improve drainage. When growing in pots, choose one that is at least 40 – 50 cm (15 – 19 inches) wide.
Bearing in mind their natural habitat is subtropical, with higher than average rainfall, finger limes are not as drought-tolerant as other citrus species. Water twice a week or more during hot spells and mulch well, which will help to retain water in the soil. Do not add mulch directly around the trunk of the plant, which can increase the risk of collar rot (Phytophthora citrophthora).
Trees are slow to establish and can take up to three years to produce fruit, and six years before they produce are able to produce a substantial crop (up to 20 kg). Removing fruit from juvenile trees is beneficial so that the tree is able to put all its energy into growing. My own finger lime produced two mature finger limes in its first year and doubled in height.
Small pink buds develop in spring and open up to reveal a white flower from which finger limes emerge. Insects increase pollination rates, therefore it is recommended you plant flowers such as lavender or marigold close to your finger limes to attract more insects. The harvest period varies depending on the variety planted but typically ranges from January to May (most common) in Australia. It takes approximately five months for the fruit to reach maturity after the onset of flowering. You will know when they are ready if they come away from the tree with little resistance. Harvesting can be tricky due to the spiky branches, a pair of BBQ tongues or protective gloves are recommended.
Fertilise four times a year with a small quantity of good-quality citrus fertiliser and top up with a soil conditioner between feeding.
Pests and diseases
Citrus melanose disease is caused by the fungi Diaporthe citri, which damages the fruit, leaves and twigs of affected plants. Small, black raised lesions are often surrounded by yellow halos and can cause leaf distortion.
Nutritional information
1 fruit (10 grams) contains:
- Calories: 5
- Carbohydrates: 1 gram
- Fibre: 0.5 grams
- Protein: 0.1 grams
- Fat: 0.1 grams
- Vitamin C: 4.5 milligrams (approximately 7% of the recommended daily intake)
- Folate: 3.5 micrograms (approximately 1% of the recommended daily intake)
- Potassium: 10 milligrams (less than 1% of the recommended daily intake)
- The pearls (or citric caviar) consist of malic acid, citric acid, lactic acid and glycolic acid and contain three times the level of vitamin C as mandarin. Vitamin C is an essential micronutrient that plays an important role in immune function by supporting the cellular functions of both the innate and adaptive immune systems.
Finger limes are a good source of antioxidants, which can help protect against cell damage from free radicals. Other nutrients are believed to include folate, potassium and Vitamin E.
What are finger limes used for?
Australian finger limes have a unique flavour and texture that make them a versatile ingredient for a variety of dishes. Unlike other varieties of citrus, you do not peel finger lime, instead, cut it in half and squeeze out the pearls. Both the skin and pearls are edible.
- Drinks: Gin and tonic, vodka and soda, margarita, martini and mojitos
- Baking: Finger lime juice caviar and zest can add a subtle citrus flavour to cakes and muffins
- Dressings and marinades: Finger lime caviar can be used to add a unique twist on classic salad dressings, mayonnaise and marinades
- Preserves: Marmalades, jams and chutneys
- Desserts: Finger limes can be used in place of lemon or lime for cheesecake, ice cream, sorbets and tarts
- Seafood: Finger limes pair well with oysters, ceviche, sushi and grilled fish
- Salsa: Finger lime caviar can be mixed with tomato, onion, and chilli peppers to create a zesty salsa
Pairings:
Finger lime pairs well with avocado, chicken, coriander (cilantro), mint, basil, cumin, coriander and chilli.
Storage
Once picked, finger limes can be stored in a cool room (below 8°C) for 4-5 weeks. Finger limes freeze well and can be defrosted quickly under running cold water.
Are finger limes toxic to dogs and cats?
All citrus species contain essential oils limonene and linalool as well as psoralens which are toxic to pets in large quantities. Due to the tart taste of finger limes, most cats and dogs will not consume enough to pose a significant risk