Choose a spot to plant your luffas in full sun. Spread 6 inches of compost and work it into the top 12 inches of soil. Rake the area to smooth the soil and break up any clods.
Soak luffa seeds for 24 hours before planting, or use a nail file to file the pointed end down and soak them overnight. Luffas are slow to germinate, and this will speed germination.
Erect a sturdy trellis to support the heavy luffa vines and ensure long, straight fruits. Fruits grown on the ground tend to rot easily.
Plant luffa seeds in a row 1/2 inch deep and 12 inches apart. Water the site well daily until the seeds sprout, which may take up to two weeks. Luffa seeds may sprout erratically, with some taking much longer than others.
Mulch around the sprouts when they get their second set of true leaves. Do not let the mulch touch the sprouts.
Remove all the first flowers, which will be male flowers. Male flowers grow in clusters, whereas female flowers are solitary and have an attached ovary. Remove the first four lateral branches to get later, but larger and better fruits.
Water regularly, as luffa vines grow vigorously, but do not allow the ground to become soggy. Fertilize monthly with an all-purpose vegetable fertilizer. Pick fruits 4 to 6 inches long to use as vegetables. Allow fruits to dry on the vine to use the fibrous interior as a sponge.