Back in 2019, Epic Gardening created the Luffa Challenge and saw amazing results from our followers all over the world! So many people grew this intriguing plant with great success that we thought we’d share some tips and tricks with gardeners everywhere. So, if you haven’t grown one already, let’s take a shot at growing luffa, the homegrown shower sponge!
Many people think all shower sponges come from the ocean, but most commercially-produced sponges are actually dried fruit. The luffa plant is a climbing vine that produces cucumber-like gourds. As the gourds mature, their endocarp transforms into a fibrous network that’s mostly made of cellulose. This network forms the soft and absorbent exfoliator we’re all familiar with.
Though they’re most commonly used in the shower, luffa sponges are great for scrubbing pots, cleaning shoes, making mats, and painting textures. They’re even used as shock and sound absorbers as well as for filtering water. There isn’t much this vegetable can’t be used for!
The same goes for immature fruit. When still green, luffa gourds are just as tasty as the sponges are useful. They can be eaten raw or cooked. They highly resemble cucumbers, zucchini, and winter squash and are often cooked the same.
Whether you want to try a new veggie on your plate or a sponge in your shower, luffa is an excellent choice for your garden. This plant is a bit tricky to grow, so we’ll go into detail on how to succeed with this nifty plant.
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Quick Care Guide
|Common Name(s)||Luffa, loofah, sponge gourd, dishcloth gourd, Egyptian cucumber, Chinese okra|
|Scientific Name||Luffa cylindrica, Luffa aegyptiaca, Luffa acutangula|
|Days to Harvest||2-6 months|
|Fertilizer||Diluted, nitrogen fertilizer|
|Pests||Pumpkin flies, cucumber beetles, squash bugs|
|Diseases||Powdery mildew, downy mildew|
All About Luffa
Luffa plants are in the Cucurbitaceae family, also called the gourd family, which includes cucumbers, squash, pumpkins, and melons. There are over 900 species in this family, but only seven of them belong to the Luffa genus. We’ll be focusing on the cultivated species, particularly Luffa cylindrica (also known as Luffa aegyptiaca). Another common species is Luffa acutangula, which you may recognize as Chinese okra. Unlike the smooth cylindrica, its sides are ridged, earning it the nickname “angled luffa”.
Although Luffa is the correct spelling of the genus, ‘loofah’ is a widely accepted common name. You may hear this plant go by loofah sponge, dishrag gourd, or vegetable sponge. It’s also called Egyptian cucumber, but its specific origin is unknown. Luffa is believed to have originated from somewhere in Southeast Asia. In fact, it grows wild and has escaped cultivation across Asia and Africa. In the US, luffa isn’t common for commercial growing as we import most of our luffa sponges from Japan. However, luffa plants are a great addition to home gardens in zones 5-11.
Luffa plants are climbers. They grow vines that can shoot up to 50 feet tall in just one growing season, like hops. Adorning the vines are large, star-shaped leaves with a bit of a fuzzy texture. There are also cheerful, bright yellow blossoms. Loofah is a monoecious plant, which means it has separate male and female flowers on the same plant. The male flowers are larger and clustered together. Female flowers, on the other hand, are smaller and solitary.
Since they’re annuals, you’ll get a fresh start at growing luffa gourds each year. After planting in the spring, the luffa vines take 2-3 months to fruit and another month or two to mature into sponges. As the cucumber-like fruit further matures, the smooth surface becomes ridged, indicating that a network of fibers is hardening inside the gourd. On the outside, the skin becomes loose and papery. When shaken, you can hear the seeds rattling around inside.
Plants in the Cucurbitaceae family contain cucurbitacin, a group of biochemical compounds that plants use to deter predators. These plants usually only have a small amount of cucurbitacin so they aren’t harmful to humans. However, when consumed in large amounts, cucurbitacin can cause food poisoning in humans and animals. This chemical gives off a bitter taste, so don’t eat any loofah gourd (or other vegetables) with a strong, bitter flavor.
Because of the cucurbitacin content, you need to use a trusted seed brand to grow luffa, whether it’s your local nursery or an online shop. Homegrown or hybrid seeds have a much higher potential of producing large amounts of cucurbitacin, which can be dangerous and a waste of time. If you’re only growing loofah for the scrubber and won’t be eating it, you can be more lenient with your seed choices.
If you’ve grown cucumbers before, loofah will be very familiar. The planting and growing requirements are basically the same, with just a few tweaks.
When to Plant
Since they’re tropical plants, loofah sponges need a long, warm growing season. In fact, you’ll only have enough growing time if you live in zone 7 or higher. For zones 5 and 6, start seeds indoors so the fruit can be harvested before the first frost. The soil needs to be at least 70°F when planting, so you’ll need to start the seeds about 4-6 weeks prior.
Where to Plant
Luffa sponge doesn’t transplant well, so its place in the ground will be permanent for the rest of the year. It’s most important that you choose a spot where you can put a trellis. You’ll need a lot of vertical space, as well as 3-4 feet of spacing between plants.
Don’t plant your luffa seeds where other Cucurbitaceae plants were previously grown. There are pests and diseases that feed on the entire cucumber family that would be more likely to be hanging around in the soil.
You can grow individual plants in containers or a raised garden as long as they have enough space. Containers should be about a foot and a half deep and sturdy enough to hold a trellis as well. To make for easy watering, line the container with a cloth bag meant for growing and fill the bottom of the container with a reservoir of water.
How to Plant
Soak your luffa seeds for 24 hours. This will soften the seed coat and greatly increase the chances of germination. After they’re done soaking, immediately sow seeds either in a seed starting tray or their permanent home outside (depending on your climate).
Plant the luffa gourd seeds ½ inch deep in well-draining soil. For outdoor planting, make 6-inch tall mounds and plant a few seeds in each. It’ll take about 1-2 weeks for the loofah seeds to germinate. After they’ve sprouted, thin the luffa seedlings down to one per mound.
Luffa seeds starting out in a tray will need a heating mat set to 70-85°F. After the seeds have sprouted, remove the heating mat. When the weather is warm enough outside, carefully transplant each luffa seedling in the ground.
Whether you planted straight in the ground or transplanted, cover the soil with a layer of mulch. It locks in heat and moisture and also supplies nutrients as it decomposes into the soil.
The basic care requirements for loofah gourds are quite simple. However, when it comes to fertilizing and pruning, you’ll need to pay close attention.
Sun and Temperature
Luffa gourds need lots of sunlight. Throughout the entire growing season, they should be getting at least 6 hours of full sun. The more light they get, the better. That’s why this plant grows best in at least zone 5.
For your luffa sponge to survive, the temperature must always be above 50°F. It should be even higher if you want the plant to thrive. If the temperature dips down even after the danger of frost has passed, try to maintain warm soil by laying down more mulch, landscape fabric, or a clear dome (if the plant is small enough).
Water and Humidity
From the very start, you’ll be keeping the soil consistently moist. Luffa needs medium watering, so the soil should never dry out, but never be waterlogged. Keep your luffa watered at the roots only. Getting the leaves or immature fruits wet can encourage fungal growth and invite pests.
Loofah does well with most soils as long as they’re fertile and well-draining. Ideally, use a sandy loam as clay soil blocks water drainage. The soil should be rich with organic matter and have a slightly basic pH (about 6.0 – 6.5).
All that growth needs lots of nitrogen to support it. Supplement the soil with nitrogen fertilizer a few times throughout the growing time. Most gardeners will apply a slow-release fertilizer just after transplanting and again when the loofah starts to blossom. If you aren’t seeing much growth during the summer, supplement with a half-dose of liquid nitrogen fertilizer every few weeks.
Pruning and Training
To keep your loofah vines healthy and tidy, provide a sturdy trellis or fence. Although they will grow on the ground, it’s very easy for disease to spread and the fruit to rot there. Trellises provide the air circulation needed to keep the plant healthy. Arch trellises are a great choice as they make for easy harvesting since the fruit will hang down away from the leaves.
It’s also essential that you prune your loofah properly. Remove most lateral growth so there’s just one main vine. When the loofah blossoms, limit the fruit set to about 20 per plant. If your zone has a long warm season, clip off the first few blooms so the plant can get more established before growing fruit.
Near the end of the season, clip back new growth so all the energy can be directed into the fruit. This will help them mature faster, which is essential if winter is coming fast.
Since loofah is naturally an annual, it’s only propagated by seed.
The seeds inside the mature gourds are dispersed short distances by the wind after the fruit breaks open. If you harvest dried sponges, you’ll easily collect the mature seeds once peeled. Store them in a dry, dark, and cool place until next spring.
If you’re growing loofah to eat, remember to only use store-bought seeds. However, if you’re only planning to harvest sponges, you can definitely save your own seeds.
Harvesting and Storing
It’s the end of the season and hopefully you have some of your own luffa sponges to show for it. Whether you want to eat them or craft, we’ll clue you in on how to harvest.
Harvesting Luffa To Eat
Remember that loofah gourds grow fast, so for edible loofah, you have to pick it on time. Otherwise, they’ll be a bit too fibrous to eat. Pick young loofah gourds when they’re under 6 inches long (about 2 months after planting). The fruit will be green and resemble a funky-looking cucumber.
If planning to harvest both luffas to eat and use as sponges, let the first few turn into sponges and harvest the later fruit for food. This will ensure you have plenty of time for the luffa gourds to mature.
Eat your green luffas raw or cook them in place of zucchini or summer squash. These gourds are particularly popular in stir-fries and scrambled eggs.
Unless they’re completely dried, luffa fruit don’t store well. You may be able to squeeze a few extra days of life into them by storing them in the fridge wrapped in a paper towel. Your best option, however, is to eat this vegetable as soon as possible.
Harvesting And Preparing Sponges
Mature luffa gourd is ready to harvest about 3-6 months after planting. It’s essential that you let the fruit completely mature on the vine, even if it means a very long growing season. As the green skin fades and the fruit starts losing moisture, cut back on watering to help it completely dry out.
When your loofah sponges are ready to pick, the outer skin will turn brown and papery and start to separate from the fibers underneath. They’ll be surprisingly light when you pick them up. If you shake the gourd, you’ll hear the seeds rattling inside.
After harvesting, peel off the outer shell, starting from the top or bottom. If the sponges are ripe, the skin will come off easily. The seeds are located at the base of the fruit and should fall out easily. If you’re having trouble getting all the skin off, soak the gourd in water for 2-3 days and try again.
Now that you have your homegrown sponge, give it a rinse and a quick sun-dry. Some gardeners will even soak their sponges in a 10% bleach solution for an hour or two to disinfect and turn it white. You can make use of the holes in the center and loop a cord through it for hanging or glue a dowel inside to make a handle. If you want multiple pieces, the fibers are easy to cut with a serrated knife.
Many of the pests and diseases for loofah are shared with cucumbers, winter squash, and other gourds. Thankfully, that means we already know how to deal with them so we can keep our vigorous vines healthy!
You can normally expect at least 5-10 fruits per plant. If you aren’t getting many fruits, it’s likely that you’re overwatering the plant roots. Too much water, especially during blooming and fruiting, can greatly decrease the yield. Cut the water to just enough to maintain the soil moisture and your plant should start to produce.
Another issue we see with loofah is the flowers or immature luffas falling off. This isn’t a sign of a weak vine, but of improper pollination. If the fruit isn’t pollinated, the plant has no use for it and will stop putting energy into producing. You’ll have to ensure proper pollination by doing it yourself with a q-tip or paintbrush. If you only have one plant, try planting multiple ones next year so you have a greater chance of the female and male flowers opening at the same time.
Pumpkin flies are orange and brown menaces that lay their eggs on immature gourds. The maggots then feed on the gourd, causing dry, dark brown, sunken regions. The damage will start to rot, making the fruit far from palatable. To control these pests, catch the problem early on by destroying any fruit with said lesions and completely removing it from the garden (don’t add it to your compost bin!). This ensures that the maggots present can’t continue reproducing in your garden. If the problem persists, you can use an organic pesticide that contains fenthion or pyrethrin.
Cucumber beetles may be pretty, but they’ll wreak havoc on any Cucurbitaceae plants in your garden. These pests will feed on roots and leaves, often spreading disease along with the damage. Like pumpkin flies, pyrethrin insecticides are useful against cucumber beetles. However, they don’t always work on this resilient pest, so you may need to turn to ladybugs and lacewings to get the job done. You can prevent future infestations by using floating row covers or dusting your plants with kaolin clay.
The notorious, flat, brown squash bugs may have their sights set on your luffas. They’ll feed on the fruit and leave their gross eggs underneath the leaves. In the winter, adult squash bugs hunker down in leaves, rocks, and other debris. A good place to start is keeping the soil clear and removing spent plants. Basic pest repellents like diatomaceous earth and neem oil work well here, though diatomaceous earth won’t harm the adults. For more serious cases, pyrethrin sprays can be used from spring to early summer. Bagging the fruit in a breathable, stretchy cloth bag can protect it from squash bug damage, too.
If you have your own garden, you’re sure to encounter powdery mildew at some point or another. This common garden disease leaves a powdery, white dusting on the leaves and saps away the plant’s nutrients. The spores spread by the wind, so it’s very important that you remove any diseased plant material immediately. Neem oil, copper fungicide, and sulfur fungicide are good options for handling powdery mildew.
It may look and sound like powdery mildew, but downy mildew brings its own problems to the garden. It’s a fungal mold that thrives in warm and humid conditions. Instead of white powder, it makes yellow and brown spots on the leaves. Downy mildew can spread through infected seeds, so if you notice this disease you shouldn’t save your own seeds for next year’s planting time. As always, neem oil is a great option here, as well as a copper fungicide. To prevent this disease, ensure that you’re only watering at the base of the plant so the vine, leaves, and fruit are dry.
Frequently Asked Questions
Q: How long does it take for loofah to grow?
A: Loofah for eating will be ready in about 2 months. Loofah sponges, however, take anywhere from 3-6 months to fully develop their fibrous flesh.
Q: Is luffa hard to grow?
A: It’s picky about a few things, like sunlight and not being transplanted, but loofah shouldn’t be too hard for an intermediate gardener.
Q: How many loofahs does a plant produce?
A: Most plants will usually produce at least 5. However, some can grow over 20 loofahs!
Q: Can you grow luffa on the ground?
A: You can, but we don’t recommend it. It’s really easy for the fruit to rot when it’s on the ground.
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