How to grow Finger Lime in Australia

Where to plant

Finger limes grow in full sun or dappled light. In cooler climates, a partly shaded, north-facing spot suits them best. Shelter them from strong prevailing winds, as the fruit is easily scratched by the plant's own thorns. Like all citrus, they need well-drained soil, ideally pH 6 to 7. Grafted trees on Citrus trifoliata rootstock cope better with heavier soils. They can withstand light frost once established.

The tree is very thorny, so plant it away from paths and play areas. Its dense, prickly branches make good habitat for small birds, and it can be grown as a hedge or espaliered against a fence or wall.

• South East Queensland, the Northern Rivers, Sydney and Perth: plant any time from March to October, avoiding the hottest months.
• Melbourne: plant in October or November once frosts are over, in a warm, sheltered spot, and protect young plants on cold nights.
• Adelaide: plant in September or October in a sheltered spot with shade from hot afternoon sun. In the Adelaide Hills, protect young plants with frost cloth for their first winters.
• Hobart: marginal. Plant in October or November in a sheltered, frost-free spot or a pot.
• Canberra: our calendar marks Canberra as unsuitable outdoors. Grow it in a pot that can be moved under cover for winter.
• North Queensland and Darwin: plant in the dry season, from May to October, and water regularly until the wet.

Choosing a variety

Buy a grafted tree. Finger limes are slow from seed, taking up to 15 years to mature, and cuttings are slow and have a low success rate. Grafted plants grow faster and fruit sooner because the grafted wood comes from a mature tree.

Named cultivars differ in fruit and pulp colour, from green and yellow to pink, red and near black. Examples include Rainforest Pearl, a vigorous grower with pink fruit, and Alstonville, a tall shrub with dark green to black fruit and pale green flesh.

How to plant

1. Plant at any time except the height of summer, when it is hard to keep a new tree watered.
2. Choose a well-drained spot, or build a mound on heavy soil.
3. Water the tree in its pot, then plant it at the same depth, with the graft union above the soil.
4. Water in deeply and mulch, keeping the mulch clear of the trunk.
5. Wear thick gloves when handling it; the thorns are long and sharp.

Watering and feeding

Keep the soil moist through summer, and mulch in spring to hold moisture. Water deeply rather than often, and never let the roots sit in soggy soil.

Feed small amounts of a citrus fertiliser every 2 to 3 months through the growing season. Regular small doses of a soil conditioner such as seaweed solution or worm castings also help. Potted trees need feeding more regularly than trees in the ground.

Pruning and care through the year

• Prune lightly to shape, or clip as a hedge. Remove dead twigs, which carry melanose.
• Check for citrus gall wasp from June to September, when the swellings on young stems are easy to see, and cut them off by late August before the adult wasps emerge. Do not put the prunings in compost or green waste.
• Knock bronze orange bugs into a bucket of soapy water, wearing gloves and eye protection, as they squirt a liquid that burns.

Harvesting

Small white or pale pink flowers appear in late summer and autumn, and the fruit, about 3 to 12 cm long, ripens from winter into spring. Pick fruit when it has reached full colour for its variety and feels slightly soft, and when it comes away from the branch easily. Ripe fruit often falls, so check under the tree. Wear gloves to pick.

Fruit keeps for a couple of weeks in the fridge and freezes well whole.

Growing in pots

Finger limes grow well in a large pot, at least 40 cm wide, which also lets you move them under cover in cold areas. Use a quality, free-draining citrus potting mix, keep it moist through the warm months, and feed lightly every couple of months.

Using it

Cut the fruit across and squeeze out the beads of pulp. Use them on seafood, in drinks, on desserts, as a garnish or in marmalade.