How to Grow and Care for Luffa

Luffa (Luffa aegyptiaca), also frequently spelled "loofah," is a fast-growing, tendrilled annual vine in the cucumber family. Its large yellow blooms attract bees and butterflies and produce gourds when pollinated. The vines grow up to 30 feet long, with 10-inch long, palm-shaped leaves.

The plant is native to Asia and grows best in hot weather, acidic soil, and at least six hours of sunlight. The unique luffa gourd fruits are eaten or dried for use as natural sponges.

Luffa gourds take about 90 to 120 days to grow and up to 200 days until they are ready to be harvested for sponges.

How to Plant Luffa

When to Plant

Direct seed it in late spring or start it indoors four to six weeks before the last average frost date in your location.

Select a Planting Site

Select a location with full sun and well-draining acidic soil with a pH between 6.0 to 6.5.

Luffa is a large vine that requires ample vertical space. When selecting a location, take into consideration that it will cast shade on the surrounding plants.

Spacing, Depth, and Support

Space plants 12 to 18 inches apart in rows 5 feet apart.

Provide a trellis or posts with wires to allow vining and air circulation. Luffa that is grown on the ground tends to be curved. Growing it on a trellis keeps the vines and fruit dry and off the ground, which reduces the risk of disease and rotting in humid or wet weather. The trellis can be designed like a trellis for cucumbers and beans but it needs to be sturdy enough to support the weight of the mature luffa gourds. Alternatively, use 4-inch by 4-inch posts, set 10 feet apart, with heavy gauge horizontal wires at even intervals to the top. To train the vines, add a string in a V-pattern so the tendrils of the vines have something to grab onto.

Luffa Plant Care

Light

Luffa needs at least six hours of full sun—the more the better.

Soil

Luffa grows in any soil type but it prefers a pH range of 6.0 to 6.5. Excellent drainage. however, is key.

Water

Keep the soil moist but not wet until the seedlings are established. After that, without sufficient rain, water the base of the plants with about 1 inch per week. Do not get water on the vines, which encourages the spreading of disease.

Temperature and Humidity

Luffa needs warm to hot weather. In cool weather, its growth will slow down. High humidity is not an issue.

Fertilizer

Add organic matter to the soil before planting, and add nitrogen-rich fertilizer two to three times
during the growing season. For the amount to use, follow the product label instructions.

The plants should have male and female flowers. A lack of either one is an indicator that the nutrient levels in the soil need adjustment. Soil high in nitrogen yields more male flowers; soil high in phosphorous produces more female flowers. Feed the plants a water-soluble, quick-acting fertilizer according to your plant's output of male vs. female flowers.

Pollination

Crop and fruit production of luffa requires pollination. Male and female flowers look similar, but male flowers grow on a long stalk and are usually the first to appear. The flower blooms for one day and then falls off. The female flower grows on a short stalk (peduncle) but has an ovary in the shape of the fruit. The pollination of female flowers occurs primarily through bees.

If you notice a lack of bees, consider hand-pollination when the plants are flush with flowers:

1. Use a small paintbrush or cotton swab to move pollen from a male flower to a female flower or gently rub the male flower's yellow hair-like structures against the female flower's middle parts.
2. Repeat for two to three days. Fruits should start to form shortly after pollination.

Types of Luffa

Luffa aegyptiaca, also called smooth luffa or sponge gourd, is the variety most widely available from seed companies. Common cultivars include: 'Smooth Boy', 'Smooth Beauty', and 'South Winner.'

There are two other luffa species:

• Angled luffa (Luffa acutangula): Also called Chinese okra, dishcloth gourd, or ribbed loofah, its immature fruits are popular in Asian cuisine. Common cultivars include: 'Lucky Boy,' 'Hybrid Green Glory,' 'Summer Long,' and 'Hybrid Asian Pride.'
• Ball luffa (Luffa operculata): Also used as a fibrous scrubbing sponge similar to Luffa aegyptiaca.

Luffa vs. Snake Gourd

Snake gourd (Trichosanthes anguina or T. cucumerina) is a tropical vegetable widely used in South Indian cuisine. The fruit is up to 5 feet long and curls as it grows. It is a climbing vine but unlike luffa, it is grown solely for culinary purposes. Snake gourd has a waxy skin; it is harvested young and becomes bitter as it ages.

Harvesting Luffa

You can harvest luffa when it is still young and tender for eating it raw or cooked. The fruit grows fast, about an inch-and-a-half per day. Expect about four to six fruits per plant.

To grow luffa for sponges, let them grow about two feet long. Here's how to harvest them:

1. Once the fruit has reached maturity, allow it to remain on the vine for several weeks to give it time to develop its tough inner fibers. Give it 150 to 200 warm, frost-free days from seed to harvest.
2. Dry it on the vine before harvesting it. Cut the fruit from the vine with one to two inches of the stem attached; they should be tan and lightweight. Their skin should be thoroughly dried to a hard shell. When you shake a luffa, you should hear the seeds rattle inside, which indicates that the inside fibers have also dried and hardened.
3. To make sponges, immerse the luffa in warm water for about 20 minutes or until the skin is easily removed. Remove the seeds by shaking them loose, and remove any pulp.
4. Once the luffa is gutted, soak it with a 10 percent bleach solution for one hour to kill bacteria. If you prefer not to use bleach, rinse it well under fresh water, shake it to remove excess water, and microwave it for one to three minutes until it's steaming hot. Allow it to dry in a warm, well-ventilated place before storing.

How to Grow Luffa in Pots

While it is possible to start luffa as seedlings indoors in pots, they will eventually need to be transplanted outdoors.

It is also possible to grow luffa plants in large pots in a container garden if you provide a trellis or support structure for the plant to vine upwards. Also, ensure the container has ample drainage holes since this plant does not like wet feet (consistently wet roots) or soggy soil.

Since luffa is an annual, repotting is not necessary.

Pruning

Trim young plants with sterilized pruners. To encourage vigorous branching, cut four stems back to the main stem.

Once the plant develops fruits, about two months before your first expected frost date, pinch away all the flowers and any small luffa on the vine. Pinching the most miniature fruits and flowers will direct the plant to put all its energy into growing the existing luffas on the vine into larger fruits.

How to Grow Luffa From Seed

Luffa is propagated from seed. Because of its long growing season and warm temperature requirements, it is best seeded directly in your garden. In cooler climates, start the seeds indoors four to six weeks before the last average frost date in your area.

1. In late spring, when the soil temperature has reached at least 70 degrees F, sow seeds in well-drained, tilled soil, three to four seeds per plant, and leave about six feet between the plants. Do not plant luffa in a location where you grew other members of the cucumber family (Cucurbitaceae) the year before.
2. Cover the seeds with 1/2 to 3/4 inches of fine soil, lightly tamp them, and moisten them evenly.
3. Ideally, seedlings emerge in seven to 14 days, but germination may be slower depending on the seed quality and soil temperature.
4. Thin to one seedling, keeping the most vigorous plant, when they are one to two inches high. If you don't start with a trellis but plan to drive posts or a cage system, keep the post away from the plant's tender root system.

Overwintering

Luffa are annual plants, living their entire lifespan in one growing season. These plants do not overwinter since cold temperatures kill the vines. If frost threatens before the fruits have fully matured, cover the plants lightly at night to shield them from the frost.

Common Pests & Plant Diseases

Downy mildew, powdery mildew, alternaria leaf blight, and angular leaf spot have been observed on luffa, but thankfully luffa is not frequently affected.

Rarely, invading pests include cucumber beetles and spider mites. Practicing crop rotation and avoiding overhead irrigation helps reduce the spread of disease.