Luffa

Luffa (Luffa aegyptiaca), also called loofah or sponge gourd, is an annual climbing vine in the cucumber family. It climbs by tendrils and bears bright yellow flowers in summer. The vines can run 30 to 50 feet (9 to 15 m) long. Young green fruits can be eaten like squash or cucumber, while mature fruits turn fibrous and are used as bath sponges.

Sow seeds outdoors directly after the threat of frost has passed, but only where the frost-free season lasts at least four months. In cooler areas, soak the seeds in water for 24 hours, then start them indoors 6 to 8 weeks before the last frost date. Use biodegradable pots to reduce transplant shock. Start seeds in warm soil in late spring. Sow at 70 to 75 °F (21 to 24 °C) in early spring.

Sun and support. Plant in full sun, with at least 6 hours of direct sun a day, and give the vines a sturdy trellis to climb. The trellis also keeps the fruit off the ground so it doesn’t rot.

Outdoors and in pots. Outside, plant out in early summer against a sunny fence with climbing support. Luffa needs a long growing season for the fruit to mature. Under glass, it can be grown in large pots with support for the tendrils.

Water and soil. Keep the soil evenly moist and well-drained, with rich loam. The plant tolerates nutritionally poor soil. Under glass, provide high humidity and shade from hot summer sun.

Pruning. No pruning is needed.

Powdery mildew, downy mildew and various leaf spot diseases are possible. Cucumber beetles, squash bugs, thrips, aphids and spider mites can be problems. One profile describes the plant as generally pest-free but possibly susceptible to powdery mildew.

Pick young fruits while they are under 7 inches (18 cm) long, and eat them like squash or cucumber. Fruit can grow about 1 to 1½ inches (2.5 to 3.8 cm) a day, so check the vines often. Sponge fruit is ready when the skin feels loose and brittle. For sponges, harvest after the first fall frost, when the gourds are tan, light and dry and the seeds rattle inside.

After harvest, peel off the skin, shake the seeds loose and save some for next year. Soak the sponge in a mix of 10 parts water to 1 part bleach for about an hour, then let it dry.

Eat only young fruit, and don’t eat any fruit that tastes bitter. Wear gloves and other protective equipment when handling the plant.