Loofah, also known as luffa or lufah, is the fruit of a tropical vine grown for use as a kitchen or bath sponge, and in some places as an edible vegetable. Loofah plants require a long growing season and may not reach maturity in areas with short summers. However, they are easily grown and harvested in many temperate climates around the world. Loofahs are most commonly grown from black watermelon-like seeds, which can be found at garden centers. They are similar to cucumbers in growing habits and require only minimal care to thrive in the home garden.
Soak loofah seeds in warm water for 48 hours to speed germination. Plant them in peat pots and place the pots in a warm, bright and moist location. Start loofah seeds indoors in spring about three weeks before the last frost in your area.
Place a sturdy trellis at least 5 to 6 feet high along the back of the planting area, which should receive full sun and have fertile, well-drained soil. An area along a fence can also be used, as loofah plants need to climb or they will overtake the garden.
Plant loofah seedlings 8 to 12 inches apart and water deeply. Continue watering once per day until the plants are well established, and then reduce watering to once per week. Avoid overwatering established loofah plants, as excessive moisture can cause root disease and poor growth.
Spread a 1-inch layer of mulch around the loofah plants immediately after planting and watering. Begin the mulch layer about 3 inches from the stem of each plant to allow room for growth and prevent stem rot. Use grass clippings to mulch loofahs for the best results and avoid heavy bark mulches.
Apply a balanced liquid fertilizer to loofah vines once per season when yellow flowers appear, usually around midsummer. Water thoroughly both before and after application to prevent root burn and distribute nutrients throughout the soil.
Remove all the first flowers that appear and the first four lateral branches of each plant to increase the yield and quality of fruit. Snip off branches using pruning shears and remove flowers by pinching them off with your fingers as close to the stem as possible. Remove any damaged or spotted fruit from the vine immediately, as it cannot be saved.
Harvest loofah sponges when they have matured on the vine, usually around the end of fall. Look for lightweight fruit with dry, dark yellow or brown skin. Leave the fruit on the vine as long as possible, but remove all loofahs immediately after the first frost or they will begin to rot.