Key Technical Points for Soilless Cultivation of Luffa and a Detailed Guide to Planting Time

Luffa is a common vegetable. The "Luchuan Materia Medica" records: “luffa promotes fluid production and quenches thirst, relieves summer heat and eliminates restlessness”. The "Collected herbal prescriptions" also records: “it treats women's leukorrhea, strangury with blood, distension and accumulations, and all aches and pains of the sinews and bones”. It can be seen that eating luffa is very helpful for health care. Which techniques must be mastered for soilless cultivation of luffa? When is it generally planted?

I. The effects and functions of luffa

1. Luffa is sweet in taste and cool in nature, and enters the liver and stomach meridians. It has effects such as clearing summer heat and cooling the blood, detoxifying and relieving constipation, dispelling wind and resolving phlegm, moisturizing the skin and improving appearance, unblocking the meridians, promoting blood circulation, promoting milk secretion, and regulating irregular menstruation. It can also be used to treat conditions such as febrile disease with bodily heat and polydipsia, phlegm and dyspnea with cough, intestinal wind and hemorrhoids, abnormal uterine bleeding, leukorrhea, strangury with blood, boils and carbuncles, and failure of milk secretion in women.

2. Luffa also has effects such as clearing heat and resolving phlegm, cooling the blood and stopping bleeding, beautifying the skin, and fighting cancer, and can treat conditions such as aching pain of the sinews and bones and bloody stool. Luffa is rich in B vitamins and has the effect of strengthening the brain; it also contains saponin substances and has a certain cardiotonic effect.

3. Anti-scurvy

Luffa has a relatively high vitamin C content, containing 8 mg per 100 grams, and can be used to fight scurvy and prevent various vitamin C deficiency disorders;

4. Strengthening the brain and heart

Luffa is rich in B vitamins and has the effect of strengthening the brain; it also contains saponin substances and has a certain cardiotonic effect.

5. Beautifying the skin

The juice of luffa vine stems has the special function of maintaining skin elasticity and can beautify the skin and remove wrinkles;

II. When is luffa generally planted?

1. Winter-spring cultivation: sown from November to January-February of the following year, harvested and marketed from December to April of the following year.

2. Summer-autumn cultivation: sown from June to September, harvested and marketed from July to November.

III. Soilless cultivation techniques for luffa

1. Raising seedlings

Use nutrient pot seedling raising. Soak selected seeds in warm water for 4 h, then disinfect with 0.1% potassium permanganate for 2-3 h, remove and rinse with clean water, and germinate at a constant temperature of 25-30 degrees C. When 80% of the sprouts grow to 0.3-0.5 cm, choose a sunny morning and sow them individually into nutrient pots filled with substrate, cover with 1 cm of substrate after sowing, and then cover with a layer of film to keep warm and retain moisture.

2. Seedling-stage management

Temperature management

For 3-4 d after sowing, maintain 30-32 degrees C during the day and 18-20 degrees C at night. Remove the plastic film promptly after emergence. After the seedlings are uniform, lower the temperature appropriately, maintaining about 25 degrees C during the day and 15-18 degrees C at night. After about 30 days, when the seedlings have 3-4 true leaves, they can be planted out; hardening of the seedlings should be strengthened 10 days before planting out.

Water management

The substrate moisture should reach 60%-70% of the maximum field water-holding capacity, and watering in the morning is best.

Light management

The seedling stage is a critical period for flower bud differentiation. Low night temperature and short daylight help promote flower bud differentiation and female flower formation, so the light duration and day-night temperature difference should be well regulated. Shading with a small arched shed can be used to control the daily sunshine duration to 8-9 h.

3. Cultivation trough specifications and substrate ratio

If producing in a greenhouse or plastic tunnel, the cultivation trough specifications are 70-80 cm wide, 25-30 cm deep, and the length depends on the greenhouse span. If it is cultivated on a designed melon-and-fruit corridor, either trough cultivation or bag cultivation can be used on both sides of the corridor, and a planting trough width of 40 cm is sufficient. Lay a layer of plastic with drainage holes flat on the bottom of the cultivation trough.

For the cultivation substrate, use peat : vermiculite : perlite = 3 : 1 : 0.5 by volume. After mixing evenly and disinfecting, fill it into the cultivation trough, shape the substrate into a turtle-back form, cover with a layer of black plastic film, and water the substrate thoroughly before cultivation.

4. Planting out

When luffa seedlings have 3-4 true leaves, they can be planted out. It is best to plant out on a clear morning. For greenhouse trough cultivation, use double-row planting, with a small row spacing of 60 cm, plant spacing of 40 cm, and a spacing between planting troughs of 80-100 cm. Take care to protect the root system so that it remains intact and undamaged. The planting density varies depending on variety, cultivation region, cultivation season, and pruning method, and is generally controlled at about 2000 plants per mu.

5. Temperature and humidity management

Within 1 week after planting out, a relatively high ambient temperature should be maintained, about 28 degrees C during the day and 15-18 degrees C at night. To prevent high temperature from damaging the plants, ambient humidity can be increased. After the seedlings have recovered, in order to promote root development and prevent excessive vegetative growth of stems and leaves, control the daytime temperature at 20-28 degrees C and the nighttime temperature at 12-18 degrees C. During the flowering and fruiting stage, the temperature can be raised slightly, but the maximum air temperature in the tunnel must not exceed 35 degrees C, and the night temperature must not be lower than 10 degrees C. While keeping warm, strengthen ventilation and air exchange, and the ambient humidity should be controlled at 60%-70%.

6. Nutrient solution management

The nutrient solution concentration management indicators are: 1.0 mS/cm at the seedling stage, 2.0 mS/cm from planting out to the flowering stage, 2.5 mS/cm during the fruit enlargement stage, and 2.8 mS/cm from the maturation stage to the harvest stage.

The suitable pH value for luffa growth is 6.0-6.8.

Luffa likes a humid climate and is tolerant of high humidity, so the substrate should be kept moist. Generally, during the seedling stage, supply the solution once every 1-2 d; at the mature stage, supply the solution 1-2 times per day, with each supply amount ranging from 0.5 L to 2 L per plant according to plant size. On sunny days, the nutrient solution concentration can be appropriately lowered, and on rainy days and in low-temperature seasons, the nutrient solution concentration can be appropriately increased. After watering with nutrient solution 2-3 times, water once with clean water.

7. Harvesting

From the opening of the female flower to harvest, luffa takes only 10-12 d. When the fruit stalk is smooth and slightly discolored, the fuzz on the fruit surface decreases, and the peel feels soft when touched by hand, it can be picked for eating. If harvested late, the fruit easily becomes fibrous, and the seeds become hard and bitter, making it inedible. Therefore, during the full flowering stage, it is best to harvest once every 1-2 d. Harvesting time should preferably be in the morning, and scissors should be used to cut at the point even with the fruit stalk. Because the luffa peel is tender, handle it gently during harvest and avoid pressing it, so as not to affect its market quality.