Citrus aurantifolia – Indonesian Lime

Site: Choose the warmest, sunniest and most sheltered position available, well clear of frost hollows.

Soil preparation: Work compost and aged manure through a free draining bed, raising the level if drainage is at all doubtful.

Hole: Dig twice as wide as the root ball and the same depth.

Planting: Set level with the surrounding soil, backfill gently, firm in and water deeply. In containers, use a premium citrus mix.

Home orchard: 2.5 to 3 metres apart, which suits its small twiggy canopy.

Pot or container: A pot of 50 centimetres or wider suits a single tree and can be moved under cover for winter.

Feature planting: 3 metres apart to allow each canopy to fill out and stay reachable from one side.

Watering: Water deeply twice weekly through the first 12 months and keep moisture even through the warm months. Never let a potted plant dry out completely.

Mulching: Apply a 5 centimetre layer of organic mulch over the shallow root zone, keeping it clear of the trunk.

Pruning: Prune lightly to open the twiggy canopy and remove dead wood. Wear gloves and long sleeves for the thorns.

Fertilising: Apply a complete citrus fertiliser in early spring and again in midsummer, with a liquid feed between times for potted plants.

Pest and disease: More prone to citrus leaf miner, aphids and scale than most citrus. Inspect each new flush and treat early. Protect from cold at all times.

Citrus aurantifolia needs a light, free draining sandy loam at a slightly acidic to neutral pH. Its shallow roots will not tolerate waterlogging.

Sandy soil: Ideal. Mulch well and feed lightly but often, as nutrients wash through quickly.

Clay soil: Not suitable unless planted on a raised mound and heavily improved with gypsum and coarse compost.

Loam: Good, provided drainage is sharp and organic matter is worked through.

pH: Slightly acidic to neutral preferred. Mulch with composted leaf litter to hold levels naturally.

Q: What is an Indonesian lime?
A: Citrus aurantifolia is the small fruited lime also known as Key lime, Mexican lime or West Indian lime, and as Indonesian lime in parts of the Australian trade. The tree is small and thorny and the fruit is golf ball sized with thin skin, high acid and a much stronger aroma than the common Tahitian lime.

Q: Is Indonesian lime the same as Key lime?
A: Yes, they are the same species. Citrus aurantifolia is sold under a handful of names including Key lime, Mexican lime, West Indian lime and Indonesian lime, and the differences are naming conventions rather than distinct plants. Fruit, tree habit and growing requirements are the same whichever label it carries.

Q: How big does it grow?
A: It stays small, around 2 to 4 metres tall and 2 to 3 metres wide, and is often kept nearer 2 metres in a pot or with light annual pruning. The canopy is naturally twiggy and a little irregular rather than neatly rounded, and thinning it out occasionally improves both airflow and fruit quality.

Q: Is Indonesian lime frost tolerant?
A: No. It is the most cold sensitive citrus commonly grown and frost will damage or kill it, so it should not be planted in frost prone gardens. In cool temperate districts grow it in a large pot that can be shifted into a glasshouse, onto a verandah or against a warm wall from May to September.

Q: Can I grow it in a pot?
A: Yes, and in southern Australia a pot is usually the sensible approach. Use a container of at least 50 centimetres in a premium citrus mix, water more often than a garden tree and feed lightly through the warm months. Being movable lets you take it out of the cold, which is what determines whether it survives.

Q: Does it need another tree to fruit?
A: No. Citrus aurantifolia is self fertile and a lone tree will crop. It tends to flower in flushes rather than one clear season, so fruit often appears over a long window. Warmth is what drives cropping. In marginal climates the tree may flower well and still set only lightly.

Q: How do I look after an Indonesian lime?
A: Keep it warm, sunny and evenly watered, and never let a potted plant dry right out. Feed with citrus fertiliser in spring and midsummer. Prune only to open the canopy and remove dead twigs, wearing gloves for the thorns. Check regularly for citrus leaf miner, aphids and scale, which it is prone to.