[This article on luffa gourds appeared in The Living Soil – the Journal of the Soil Association of South Australia – in January 1985, written by Merrill Gilfillan. As the TLS editor for some years, I was at the helm during the SASA 30th anniversary in 2005, and delivered three lectures which dug up all sorts of interesting facts for the gardener from back-issues of the Journal. This one set me on the path of growing and saving the seed of this interesting vegetable. While much is written on the use of these ‘vegetable sponges’, one should not overlook the young trellis-grown fruit, which taste something like a cucumber crossed with a zucchini. Besides, they’re good fun to show off to visitors to the garden. I have plenty of seeds for South Australians who’d like some. It grows well here. The photos I found on the web though Google Images/Luffa; my thanks to the seed companies who provided them. Andrew]
The luffa, also known as the dishcloth gourd or vegetable sponge, belongs to the Cucurbitaceae family. It is native to tropical and warm temperate areas. Only two of the several species are of common economic importance - Luffa cylindrica, the most valuable, and Luffa acutangula.
The luffas are rank-growing vines with lobed leaves and tendrils. The flowers are yellow and the stamens and pistils are on separate flowers. The fruits of L. cylindrica are green, smooth and elongate, suggesting a cucumber, and they grow to two feet in length and five pounds in weight. The fruits of L. acutangula have ten sharp ribs or flanges-running length-wise.
The net-like fibrous skeleton of the gourd is the remarkable feature of luffas and one which gives them economic importance. When the fruit is ripe, the outer wall may readily be removed leaving only the compact, fibrous network; the luffa of commerce. In the core of the net, each seed is held in a pocket. The tip of the fruit comes off as a small lid at maturity, and the seeds gradually loosen and may be shaken out through the hole.
The luffa sponge network has a number of advantages over other fibrous materials which gives it economic value. Its strands form a compact network and thus makes a continuous structure. This has a large internal surface which holds water well, and so is well adapted for washing dishes, glasses and narrow jars, and for cleaning forks by thrusting them into the net. It is very resistant to wear and can be used for scouring and rubbing down painted surfaces. Luffas are used as bath sponges, especially in England. The fibre is resilient and is used for shock absorbers, table mats, packing material and stuffing material for pillows, mattresses and saddles. Also as a heat insulator in tropical helmets. The young fruits can be eaten, and the sap of the vine is believed by the Japanese to have medicinal properties. An important economic use has been as oil filters in steam ships. Thus it can be seen that the luffa deserves a place in the garden of all those people who aim to be self-reliant.
Sponges are prepared by placing the fruits when ripe in water until the outer wall disintegrates and can be removed by rubbing or brushing. Expose the clean sponges to sun and air to dry and bleach. The seeds should be removed and saved for next season, prior to curing.
Luffas are sensitive to cold and the seed should be sown only after the ground is thoroughly warm in spring. They require a 140 day growing period. Be patient if the seeds are slow to sprout, that is a characteristic of luffas. They require full sun, and soil that is rich and organic. Plant 3 or 4 seeds to a hill, ½ inch deep, with the hills 4 to 6 feet apart. (Please excuse imperial measurements). For greater production and healthier plants, place a shovelful of rotted manure or compost in a hole below the mound.
For best results in obtaining superior quality luffas, the plants should be grown up a trellis or wire fence so that the fruit does not touch the soil. If they must be on the soil, mulch well and hand turn the luffas to obtain uniform growth. More plants can be grown using this method of trellising and therefore is useful in small gardens.
Luffas require plenty of moisture during the growing season, so water in dry spells if possible. Better quality luffas can be grown by removing all the first flowers that appear on the plants, as well as fruit that is poorly shaped or diseased.
Controlled pollination is very easy as with most cucurbits, since staminate and pistillate flowers are separate. In the late afternoon it is possible to determine which flower buds will open the next morning, for the tips of these begin to turn yellow. If the tips are tied up at that time with a loop of soft cotton string, the flowers cannot open and bees are thus prevented from entering them. On the following morning, pollen can readily be transferred to the stigmas of pistillate flowers. The latter should then be bagged for a few days until the stigma dries.
Each vine should produce 20 - 25 gourds.