Idlimbu, widely known as Sour Orange or Bitter Orange (Citrus aurantium), is a small to medium evergreen tree of the Rutaceae family. It bears glossy dark-green aromatic leaves with characteristic winged petioles, intensely fragrant white blossoms, and round orange fruits whose pulp is too sour to eat fresh but prized for cooking and processing.
In Indian gardens and orchards it is valued on two counts. Its sharp, acidic juice (called 'khatta') flavours pickles, marmalades, chutneys and traditional remedies, while the vigorous, disease-tolerant rootstock is the backbone on which sweet oranges, lemons and mandarins are commonly grafted.
Tough, sun-loving and adaptable to a range of well-drained soils, the sour orange thrives in India's tropical and subtropical belts and can also be container-grown on terraces and balconies with regular feeding and watering.
Specifications
| Family |
Rutaceae |
| Native region |
Southeast Asia; long naturalised and cultivated across India |
| Mature height |
5-9 m in ground; 2-3 m when container-grown |
| Mature spread |
3-5 m |
| Growth rate |
Slow to moderate |
| Foliage |
Evergreen, glossy dark-green aromatic leaves with winged petioles |
| Flower colour |
White, highly fragrant |
| Flower season |
Spring (February-April) |
| Climate zone |
Tropical and subtropical |
Care guide
| Sunlight |
Full sun; at least 6 hours of direct light daily for good flowering and fruiting. |
| Watering |
Water every 5-7 days in summer and every 10-15 days in winter; keep soil moist but never waterlogged. |
| Soil / mix |
Deep, well-drained loamy or clay-loam soil, slightly acidic to neutral pH 6.0-7.5; avoid waterlogging. |
| Temperature |
Grows best at 15-35 C; tolerates brief cool spells but is damaged by hard frost. |
| Humidity |
Moderate humidity; tolerates dry air once established. |
| Fertilizer |
Nitrogen-rich feed such as urea three times a year (early spring, early summer, early winter), plus citrus micronutrients (Zn, Fe, Mg). |
| Pruning |
Light pruning after fruiting to remove dead, weak or crossing branches and to shape the canopy; remove rootstock suckers. |
| Repotting |
For potted plants, repot or top-dress every 2-3 years in spring into the next size container. |
| Propagation |
By seed (largely true-to-type) and by grafting or T-budding; widely used itself as a citrus rootstock. |
| Pests & problems |
Citrus leaf miner, aphids, scale, mealybug and citrus canker; monitor new flush and treat early. |
| Toxicity / safety |
Fruit is edible and safe for humans (very sour, used in cooking). Citrus essential oils in peel and leaves are mildly toxic to cats and dogs if ingested in quantity. |
| Difficulty |
Moderate |
Uses
<ul><li>Tart juice ('khatta') used in pickles, marmalade, chutneys, squashes and as a souring agent in cooking.</li><li>The single most common rootstock for grafting sweet orange, mandarin and lemon in Indian orchards.</li><li>Fragrant white flowers yield neroli/bigarade oil used in perfumery and flavouring.</li><li>Traditional household and Ayurvedic remedies use the fruit, peel and flowers for digestion, cough and cold.</li><li>Attractive, fragrant evergreen specimen or hedge tree for gardens and large containers.</li></ul>
Growing tips
<p>Plant young grafted saplings at the onset of the monsoon (June-July) so the rains help establishment; in the south, February-March planting also works with assured irrigation.</p><p>Give the heaviest feed and watering during the spring flush and fruit set, then ease off in the cool season. Mulch the basin to conserve moisture and apply micronutrient sprays if leaves yellow between the veins.</p><p>Protect young plants from strong winter cold in north India, and watch the tender new flush for leaf miner and aphids during the warm months.</p>
