How to grow Luffa in Australia

Where to plant

Grow luffa in full sun in moist, fertile, well-drained soil improved with compost, against a strong trellis, fence or pergola. The vines climb several metres. A pergola lets the fruit hang down and grow straight, and the vines make a good summer screen over a bare fence or shed.

Luffa needs a long run of warm weather to ripen fruit into sponges. Where summer is short, young fruit for eating is the realistic crop.

• South East Queensland and the Northern Rivers: luffa grows vigorously. Sow from spring into early summer.
• North Queensland and Darwin: sow in the dry season, from April to July. The NT Government says Asian melons, luffa included, grow best in the dry season, and its Top End calendar sows luffa in those months.
• Sydney and Perth: sow in the warmest spot you have in spring. Starting seed in pots under cover a few weeks early helps.
• Melbourne and Adelaide: sow in mid to late spring once the soil is warm, in a hot, sheltered position. Sponges ripen only in a long, warm summer.
• Canberra: very marginal. Sow in November after frost; fruit rarely matures fully.
• Hobart: not suited outdoors. In Tasmania luffa needs a glasshouse.

How to plant

1. Wait until all chance of frost has passed and the soil is warm, about 20 to 30°C is ideal.
2. Soak the seed overnight to help it germinate.
3. Sow 2 seeds about 2 cm deep at the base of the trellis, or in pots to plant out later, and thin to the stronger seedling.
4. Space plants about 1 to 1.5 m apart along the support.
5. Guide the young tendrils onto the trellis. When the vines reach the top of the support, pinch out the tips and weave side shoots into the frame.

Watering and feeding

Keep the soil evenly moist. Big leafy vines in summer heat are thirsty, so water deeply and often in dry weather, and mulch to hold moisture.

Dig compost into the bed before sowing and feed with a balanced vegetable fertiliser through the growing season.

Pruning and care through the year

• Male and female flowers are separate, and bees do the pollinating. The yellow flowers open in the morning and bring honey bees, blue-banded bees and carpenter bees into the garden.
• Keep fruit off the ground. Fruit lying on soil marks and rots, and fruit on a pergola hangs straight.
• Pick young fruit regularly to keep the vine producing. Leave some fruit to mature if you want sponges.

Harvesting

For eating, pick fruit young and tender, about 10 to 15 cm long. Larger fruit turn bitter and fibrous. Young shoots and leaves are also eaten in stir fries.

For sponges, leave the fruit on the vine until it is fully mature, has turned yellow to brown and feels light. When it is dry the skin cracks and peels away easily and the seeds rattle inside. If the skin is hard to peel, leave it to dry longer. Peel, shake out the seeds, rinse the sponge and dry it in the sun. Homegrown sponges are naturally creamy to tan; shop sponges are usually bleached.

Using it

Cook young luffa like zucchini, peeled and sliced into stir fries, soups and curries; it is common in Asian cooking. Young fruit can also be pickled like gherkins. Keep young fruit in the fridge for a few days. Dried sponges are used in the shower and as pot scrubbers, and they go into the compost or worm farm when worn out.

Saving seed

Collect seed from fully dried sponge fruit when you peel them. Store the seed dry for sowing next spring.