Grow Your Own Luffa Sponges

Luffa is easy to grow in your garden, and each luffa sponge lasts nearly forever. Yes, they really are sponges you can use for everything from scrubbing dirty dishes to cleaning the bathtub. Here’s how to grow your own luffa sponges.

What is Luffa?

Three different species are called luffa. All are related to pumpkins, squash, and gourds. The species typically grown for luffa sponges is Luffa aegyptiaca, sometimes called Luffa cylindrica.

Luffa is an annual vine that can grow as long as 30 feet, with a 12-foot spread. The large palm-shape leaves develop into dense foliage that can easily hide the growing luffa gourds. To control growth, you can prune the vine, if you wish.

The gourds grow 12 to 24 inches long and become dark green when mature. While they are still at the finger-size stage the gourds are edible. After trying baby luffas both raw and in stir fry, I have to report that I’m not crazy about them.

Growing Luffa

Luffa vines require 90 to 120 days to grow, and up to 200 warm days until mature sponges are ready for harvest. The annual vine is hardy in USDA zones 7 through 14, where direct sow in late spring works best. Below zone 7, where the growing season is too short, you can start the seeds indoors.

Luffa likes heat, full sun, 1″ of water per week, and slightly acidic soil in the pH range of 6.0 to 6.5. When the soil temperature reaches 70°F, plant seeds ¾” deep and 18″ apart. They should germinate within 2 weeks.

The vines get quite heavy, especially as the gourds mature, so they need a sturdy trellis to climb on. A trellis also allows for air circulation to keep the gourds from rotting. And when they hang down, rather than lie on the ground, they grow straighter. We lean a length of stock panel against our garden cottage, anchoring it well at both the top and bottom.

Luffa Blossoms

Luffa vines produce nectar that attracts ants, which in turn defend the plant from a variety of leaf-eating insects. The vines also produce an abundance of beautiful bright yellow 2″ flowers that attract lots of bees and butterflies for pollination.

The first time you grow your own luffa sponges, you might become alarmed when the blossoms repeatedly drop off without producing fruit. But blossom drop is normal.

A luffa vine produces male and female flowers separately. One of each has to open at the same time, followed by pollination, to produce fruit.

Male flowers bloom first, weeks ahead of the first female blossoms, and they drop off the vine within a day. Male blossoms have long stamens with pollen-filled anthers. The male flower buds grow in clusters on a long, thin stem.

When female blossoms finally start to appear and are fertilization by pollinators, they produce gourds. Female flowers grow singly on a thicker stem. Each has a tiny fruit at the back, which is an ovary full of unfertilized eggs.

An unfertilized female blossom will drop off, just like a male blossom. If you experience too few pollinators to produce fruit, you can help things along by transferring pollen from male to female flowers. Use a cotton swab or a small artist’s brush. Or simply pull off a fresh male flower and gently rub it against female flowers.

Harvesting Luffa

When the gourds start turning yellow/tan, or when frost threatens, it’s time to cut the fruits from the vine, leaving a 2″ stem. If they are left on the vine to dry, they might not get enough air circulation and therefore will mildew.

Drying them in the sun works best. But in rainy weather we lay them out under cover to dry.

A gourd that’s fully dry feels light in weight. The skin is brown, wrinkled, and leathery and starts pulling away from the fibers. When you shake a dry gourd, the seeds will rattle inside. To loosen any seeds that may be stuck, give each gourd a good whack.

When the skins are really wrinkled and loose, I peel them off with my fingers. Otherwise, soaking them in warm water for at least 20 minutes will soften the skins and make them easier to remove. Just make a longwise cut and peel off the skin.

Since the seeds — which look like big watermelon seeds — fall out all over the place, we peel the gourds over a trash can. Then we shake out any remaining seed, saving a few seeds to grow the next year. Gourds left on the vine may reseed by dropping some of their numerous seeds to sprout the following year.

Luffa Sponges

Depending on how you plan to use your sponges, you might want to disinfect them. Some people do so by soaking the sponges for an hour or so in 10% bleach solution. Others prefer to boil them in a mixture of water and vinegar. After a good cleaning, dry the sponges thoroughly before storing them.

Not incidentally, a real plus when you grow your own luffa sponges is that they may be used to clean things with vinegar. A synthetic sponge will fall apart when exposed to vinegar.

Even though luffa sponges are biodegradable, in my experience they are virtually indestructible. Some that I grew so long ago I can’t remember exactly when (surely a decade or more!), and have been used continuously since then, are still perfectly serviceable.

This past season, my luffas didn’t grow nearly as big as those I grew earlier, and several of them mildewed on the vine. It likely had to do with the weather being exceptionally rainy.

By the time frost threatened we ended up harvesting a lot of green immature gourds, although we did manage to get a few small sponges, which make a terrific body scrub in the bathtub. But luffa vines are well worth growing anyway, if for no other reason than the pleasure of enjoying their awesomely beautiful blossoms.