How to Grow Luffa for High Yield? The Latest Cultivation Techniques and Methods Tutorial
In Cantonese, luffa is called water gourd or winning gourd; in the Pearl River Delta, luffa specifically refers to the ridged luffa. It is a plant of the Cucurbitaceae family native to India, also known as vegetable gourd, and is widely cultivated in East Asia. It is a climbing herbaceous plant of the Cucurbitaceae family, and the luffa root system is strong. The stem is vining, five-ridged, green, and both the main vine and side vines grow luxuriantly. The stem nodes bear branching tendrils and readily produce adventitious roots. It is distributed and cultivated both domestically and abroad.
Cultivation Environment Requirements
Luffa has strong adaptability to climate and soil and does not require strict selection, but under high temperatures it grows robustly and rapidly, develops vigorously, with thick stems and large leaves, and the fruit also grows quickly. If the temperature is below 150C, growth is slow, and below 100C, growth is inhibited.
Among the gourds, luffa has the strongest moisture tolerance, especially the common luffa, which is stronger than the ridged luffa, while its drought tolerance is not strong. The timing and quantity of female and male flower occurrence in luffa vary significantly depending on the variety. Generally speaking, luffa is a short-day vegetable; under short-day conditions, female flowers occur earlier and in greater numbers, while under long-day conditions, fewer female flowers occur. However, the sensitivity to day length varies greatly among varieties.
Luffa prefers ample sunlight. If there are consecutive rainy days, it not only affects the formation of female flowers but also causes bud and flower drop, and young fruits are also prone to yellowing and wilting. Luffa is not demanding in its soil selection, but fertile loam with more organic matter and good drainage, clay loam, and sandy loam with good water retention are most ideal. The suitable soil pH is between PH6.0—6.5.
The luffa root is resistant to vine wilt disease and tolerant of root-knot nematodes, so even continuous cropping is possible, and the previous crop is not restricted. However, it is best to rotate with rice, because this not only reduces damage from melon flies, aphids, red spiders, thrips, and others, but also results in fewer weeds.
Cultivation Management Techniques
(1) Sowing period: Luffa can be sown and cultivated year-round, but sowing from December to August is most suitable. In various regions, the later the sowing after September, although female flowers occur earlier and in greater numbers, the later growth period gradually enters a low-temperature period, growth becomes weaker, downy mildew becomes more severe, and the plants tend to age easily.
(2) Sowing and raising seedlings: The seed coat of luffa seeds is relatively hard, especially for the ridged luffa, so it is advisable to germinate the seeds before sowing. That is, soak the seeds for 2 hours, then remove them, crack open the hilum area of the seed, and place them in darkness at 25—300C to germinate. When the young sprout emerges from the seed coat, sow into plug trays filled with medium, placing the seeds flat with the sprout tip pointing downward as a principle, at a sowing depth of about 1.5 cm. When 3 true leaves have unfolded, transplant to the field. The seedling period is about 11—14 days during high temperatures and about 15—18 days during low temperatures. For short-day varieties raised during long-day periods, it is best to carry out shading short-day treatment after the cotyledons unfold, in order to promote the occurrence of female flowers.
(3) Cultivation methods: Luffa generally has 3 economic cultivation methods:
1. Horizontal trellis cultivation: The trellis surface is about 1.5 m above the ground, the bed width is 5—6 m, and high beds are made. Two rows are planted per bed, with luffa planted on both sides of the furrow, at a plant spacing of 0.4—0.5 m. This method can also use grape trellises for cultivation. When luffa is first planted, other short-term crops can still be intercropped on the bed. If horizontal trellis cultivation encounters a hurricane, because the wind-receiving surface is larger, it is easily blown down, so autumn-winter cropping should be the principle. If spring-summer cropping is used, dense planting is not suitable; somewhat sparse planting is preferable, and some stems and leaves should be appropriately thinned to reduce wind resistance.
2. Tunnel-type semicircular trellis cultivation: The bed width is 4—5 m, with the beds oriented north-south as a principle. On each bed, a semicircular trellis is erected on the bed surface, with the highest point of the trellis about 1.8 m above the ground. Luffa can grow vertically, and within a unit area the trellis area is larger than that of a horizontal trellis, with good ventilation and light transmission, which is favorable for luffa development. Two rows are planted per bed, planted on both sides of the furrow, at a plant spacing of 0.4—0.5 m. The semicircular trellis is relatively wind-resistant, so in addition to being suitable for autumn-winter cropping, it is also suitable for spring-summer cropping.
3. Prostrate cultivation: The bed width is 5—6 m, with two rows planted per bed, planted on both sides of the furrow, at a plant spacing of 0.4—0.5 m. This method is suitable for cultivating short-fruited varieties of common luffa. The fruiting period should be in the dry season, because in the rainy season, the fruit easily rots when in contact with the ground, so melon pads should be used to cushion the fruit. If long-fruited varieties and ridged luffa are cultivated by the prostrate method, the fruit is easily bent and lacks commercial value. Also, in prostrate cultivation, the fruit is easily shaded by leaves, making harvesting more laborious.
(4) Fertilizer and fertilization: For the types, amounts, and methods of luffa fertilizer, in principle reference can be made to bitter gourd or bottle gourd. That is, luffa has strong fertilizer uptake, a long growth and fruiting period, and growth and fruiting proceed simultaneously, with strong fruiting ability. Therefore, after fruiting, fertilization should still continue in order to maintain continued stem and leaf growth, so that fruiting can continue uninterrupted and yield can increase. Especially after continuous rainfall, some nutrients in the soil have already been lost with the rainwater, so topdressing should be applied after rain.
Base fertilizer is applied in the base fertilizer furrow, in a band. First apply composted manure, then mix chemical fertilizers and apply them on top of the composted manure, then make a small bed and cover it with silver-black plastic film. Topdressing should in principle be applied about once every 3 weeks. Before topdressing, first irrigate the furrow, and after the water seeps into the bed, apply the topdressing on both sides of the furrow and at the bottom of the bed.
During the growth period, if magnesium deficiency occurs (ridged luffa is more prone to magnesium deficiency), magnesium sulfate can be added to pesticides for foliar spraying once a week for 2—3 consecutive times, at a concentration of 0.4% (diluted 250 times with water). When luffa plants become weak and stagnant in growth during the middle and late fruiting stages, urea can be used for foliar spraying, also at a concentration of 0.4%, and it can also be added to pesticides for spraying, once a week.
(5) Land preparation, bed making, and planting: Make high beds. While the soil is semi-dry and semi-moist, first plow open wide and shallow base fertilizer furrows along the planting rows according to the row spacing. After applying base fertilizer, first make small beds, then cover the surface of the small beds with silver-black plastic film. If operated by machine, making the small beds and covering the plastic film can be completed in one pass, burying both sides of the plastic film into the two sides of the small beds to prevent it from being blown open by wind. Later, as the luffa grows, earth up again to make large beds, completing the wide high-bed style.
Before luffa cultivation, punch planting holes in the plastic film according to the plant spacing, plant one plant in each hole, and irrigate after planting. During high temperatures, somewhat sparse planting is preferable, and during low temperatures, somewhat dense planting is preferable.
(6) Irrigation and drainage: Luffa has long stems and large leaves and a high water evaporation rate, so attention should be paid to irrigation, maintaining a moist state at all times. Irrigation is done by furrow irrigation. During rainfall, pay attention to drainage so that the roots are not soaked in water. In particular, ridged luffa is less tolerant of moisture, and the roots rot easily when soaked in water.
(7) Vine training: Luffa has strong branching. If stems and leaves are too luxuriant, it not only tends to grow excessively and is not easy to fruit, but during hurricane season when trellis cultivation is used, the trellis is more easily blown down by wind. Therefore, vines should be appropriately thinned, single-vine pruning should be carried out, and all side vines should be cut off early.
In prostrate cultivation, the main vine is made to grow at right angles to the furrow. Also, in trellis cultivation, if stems and vines hang down below the trellis, they should be led onto the trellis so that the vines are evenly distributed on the trellis.
(8) Bed surface mulching: Luffa prefers high temperatures and has a long growth period and wide row spacing, so covering the planting rows (on the small beds) with silver-black plastic film is quite economical and markedly effective. If rice straw is used for mulching, its effect is inferior to silver-black plastic film. Also, for short-fruited varieties under prostrate cultivation, the entire bed surface should be mulched with straw to prevent the fruit from contacting the ground and rotting.
(9) Fruit bagging and fruit removal: To prevent melon flies from laying eggs and causing damage, luffa is usually bagged, and bagging is carried out at the young fruit stage right after the flowers fade. Bagging also has the effect of preventing leaves from scratching the fruit skin and turning it black, and of making the fruit skin become lighter in color, and it can also prevent pesticide contamination. Luffa can be bagged with old newspaper bags or relatively thick paper bags.
From after the female flowers fade until the fruit is developing, any deformed fruit, cracked fruit, and fruit damaged by pests or diseases should be removed early to avoid wasting nutrients and reducing the growth vigor of the plant.
(10) Pests and diseases and their control methods: Please refer to the company's printed (Control Methods for Major Gourd Pests and Diseases), but luffa is relatively sensitive to the melons of pesticides and is prone to pesticide damage, so attention should be paid to the concentration used; lower concentrations are safer, and spraying should be avoided under high temperature and strong sunlight.
Downy mildew: It mostly begins on old leaves at the base. At first there are inconspicuous pale yellow small spots, and ultimately obvious angular yellow-brown lesions bounded by leaf veins, and the lesions dry up and break easily; the lesions on the underside of the leaves have a gray-black appearance, and the leaves die early.
Harvesting and Packaging
For luffa intended for eating, those with tender, delicate flesh are best, so it should be harvested before the fruit has fully grown large, before the fruit skin has hardened, before the fibers have developed, and before the flesh has become coarse and old. It is even better to harvest each according to the suitable harvest size of its variety. Never harvest too late, as this affects quality. However, if harvested too early, not only is yield reduced, but after harvest it tends to soften and wilt and does not store or transport well.
Generally, for common luffa that flowers during low temperatures, the suitable harvest time is about 10 days after flowering; for those that flower during high temperatures, they can be harvested 8—9 days after flowering. Ridged luffa ages easily after flowering, and its suitable harvest time is about 1—2 days earlier than that of common luffa.
The growth increment of luffa fruit at night is about two times greater than during the day, so harvest time should in principle be in the morning before the fruit temperature has risen. Harvest with a knife or scissors, leaving the fruit stalk about 2 cm long, with the cut surface smooth. Harvest together with the bag, place into transport boxes or baskets, and transport to the packaging site for packaging. First remove the bag, then wrap each fruit with wrapping paper to avoid scratching and reduce water evaporation, then pack into bamboo baskets or bamboo crates for transport and sale to the market. During harvesting and packaging, retain the fruit bloom as much as possible to show freshness.
For harvesting luffa sponges, only the common luffa can be used; ridged luffa is not suitable for luffa sponges. At 50—60 days after flowering, wait until the fruit skin turns brown, the fruit becomes light, the seeds turn black, and the whole fruit is fully mature or even dry before harvesting. If harvested too early, the fibers are soft and weak and not good. After harvesting mature fruits, if the quantity is small, wait until they are fully sun-dried, then peel off the outer skin, knock out the seeds, soak in bleaching water for 1—2 hours, then rinse thoroughly with water and sun-dry. Excellent luffa sponges have characteristics such as being neat, white and compact, fine, strong and tough, and full of elasticity.