Luffa: how to grow, harvest & use the sponge gourd

The luffa plant, also spelled loofah, is not usually grown purely for consumption – its ripe fruits can be dried to make sponges. Perhaps you are familiar with it as something you use to scrub your back in the bath?

With a little patience and some basic tools, it is easy to make your own sustainable and biodegradable sponges from a luffa plant growing in your garden. In this article, you will learn how to grow luffa (Luffa cylindrica; syn. Luffa aegyptiaca, Momordica cylindrica), as well as what to keep in mind when harvesting and using the sponge gourd.

Luffa: origins and characteristics

Thanks to its intended use, the luffa plant is also known as the sponge gourd or dish-cloth gourd. Like cucumbers (Cucumis), courgettes (Cucurbita pepo) and pumpkins (Cucurbita), this annual climbing plant belongs to the gourd family (Cucurbitaceae).

Wild forms of the luffa plant are found from southern Central Asia to north-eastern Australia, as well as in the South Pacific region. Cultivars can be found in tropical Asia, the Americas, and Africa. The sponge gourd grows best in the hot and humid tropics during the dry season. They thrive in sunny locations with fertile soil that is slightly acidic to neutral.

Loofah plants can grow up to 15 m long under ideal conditions and have similar tendencies to cucumbers. The pentagonal shoot axis is slightly hairy, and the luffa leaves are long-stalked and slightly to deeply lobed. The plant produces male and female flowers that both have a bright yellow corolla. Female flowers can be recognised by their two to four cm long ovary. They are solitary on the plant, whereas male flowers usually have five or occasionally three stamens and are arranged in groups of five to twenty flowers on long panicles. Both flowers emerge from the same leaf axil.

The luffa fruit is initially green with downy hairs and grows to an average length of 60 to 80 cm. Later on, the skin turns brown, thin, and papery. The loofah plant’s smooth, matt black seeds are broadly elliptical with rounded ends and have a narrow, winged edge.

How to grow your own loofah

The sponge gourd can be grown in the UK, though it will not reach the same height as in the tropics.

Location

Above all, the sponge gourd requires warm conditions, ideally in a sheltered spot in full sun. If possible, growing luffa in a greenhouse is a good option. Loofah prefers soil that is humus-rich, fertile and loose. If you want to improve your garden soil, mix in some compost for an optimal nutrient supply and some sand to loosen compacted soil. Our Plantura Organic Enriched Compost can also be added to the soil to make it more fertile. Our compost’s high humus content not only benefits the luffa plant, but also ensures stimulated, long-term biological activity within the soil and increases fertility, which improves the heat and water balance.

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Sowing

It is best to start the loofah seedlings indoors. This will give them a head start, ensuring that the sponge gourds will have enough time to ripen completely. Here is how to sow loofah seeds:

• When: March – April
• Soak luffa seeds in water for 24 hours
• Fill pots with sowing soil
• Sow seeds 1 – 2 cm deep in the pots
• Keep substrate moist
• Germination temperature: between 20 and 25 °C
• Germination time: 10 – 20 days
• Plant luffa seedlings outdoors starting from mid-May
• Plant about 50 – 60 cm apart

It is also possible to grow loofah in containers, especially on south-facing balconies. Use a pot with a drainage hole that holds at least 15 litres. It is critical that excess water can drain away easily, so put a layer of expanded clay in the bottom of the planter before filling with a permeable, nutrient-rich vegetable compost. Loofah plants love to climb, so give it a trellis or let it climb along the railing.

Proper luffa care

Since the luffa plant needs constant soil moisture, check the soil regularly for signs of drying out. Watering is especially important in the greenhouse.

Ensure a good supply of nutrients at all times. It is important to make sure that the fertiliser is not extremely rich in nitrogen, as this could inhibit luffa flower growth. When planting, add some compost to the soil and then apply a slow-release fertiliser about two months later. Our Plantura All Purpose Plant Food, for example, is ideal for this purpose. The balanced ratio of nitrogen, phosphate and potassium prevents developmental disorders in various parts of the plant. The high proportion of organic raw materials also promotes the development of the root system and soil life.

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Climbing plants like luffa benefit from a climbing aid, such as a trellis, to help guide them up. The plant can also climb along the ground in an open area. However, a layer of mulch is recommended for this.

Another sensible care measure is to remove the first flowers and fruit. This directs the energy into the growth of the luffa leaves and the plant itself, ensuring that more fruit forms later and the sponge gourd becomes strong and robust.

There is an increased risk of mildew infestation in less-than-ideal locations, such as places that are too shady or too damp; therefore, it is a top priority to find a location with suitable conditions.

Harvesting and using loofahs

The right time to harvest the sponge gourd to make a luffa sponge is when the skin of the fruit is yellow, brittle, and covered with small brown spots. When you knock on the skin, it should also sound hollow. The first ripe fruits can be expected around September. Harvest the ripe luffa gourds and place them in a dry, sunny place for several days. After drying the loofah, use scissors to cut off the stem and flower base and peel off the husk. Shake or knead the tissue to remove the luffa plant seeds and store in a cool, dry place. These can then be used for growing luffa from seed next year. Wash the remaining pulp out, and dry the luffa sponge in a warm, airy place.

Cut the luffa sponge to the desired size and you are ready to go. It can be used in a variety of ways, such as an exfoliating shower or bath sponge, or as a dish cloth for pots and surfaces in the kitchen. A loofah sponge also makes a wonderful sustainable gift.

Is luffa edible?

When the fruits of the luffa plant are harvested at a young stage, they can be eaten. Particularly in Asia, it is often enjoyed as a vegetable. It can be eaten raw or steamed and tastes similar to courgette. The same is true for the plant’s flowers. The luffa seeds, which are rich in protein and fat, can also be used to make cooking oil.

Another plant whose fruits can be prepared in the same way is the Inca cucumber (Cyclanthera pedata). Find out more about this South American climbing plant in our dedicated article.