Longevity vegetable, also known as leaf sweet potato, is an annual herb belonging to the Convolvulaceae family. Native to South American countries such as Brazil and Peru, it was introduced to Guangdong and Fujian provinces in China during the Ming Dynasty (around 1580 AD) by Chen Zhenlong from the Philippines. Initially cultivated for its tubers, this plant has become a popular leafy vegetable in recent years, especially in Hong Kong, Guangdong, and Guangxi. The tender stems and young leaves are highly valued for their rich nutritional content, health benefits, and delicious flavor. In Hong Kong, it's even referred to as the "Queen of Vegetables" due to its premium price among leafy greens. In Changshou County, particularly in Bama County of Guangxi, it's a common edible vegetable, which is why it's called a "longevity food."
Botanically, the plant has heart-shaped leaves, round or hexagonal stems that can grow up to 10 meters long, and strong branching ability between nodes. The petioles range from 15 to 25 cm in length, and both leaves and stems come in green or purple varieties.
In terms of environmental requirements, it thrives best at temperatures between 23°C and 28°C, with a maximum tolerance of 35°C and a minimum of over 15°C, especially at night when temperatures drop to 10–15°C. It prefers full sunlight, has good drought resistance, but produces higher yields and better quality in moist conditions. It grows well in loose, fertile loam soil, requiring balanced amounts of nitrogen, phosphorus, and potassium, with an absorption ratio of approximately 1:0.4:1.
When selecting varieties, not all sweet potato types are suitable for consumption. Some may have a bitter taste, making them less palatable. Ideal edible varieties should have tender young leaves, good flavor, vibrant color, no hairy texture, strong regenerative ability of axillary buds, vigorous growth, and high yield of stems and leaves. Varieties like Jingshu No. 4 and Lushu No. 7 are commonly used for leaf production.
Propagation methods mainly include cuttings, which is the most effective technique. Strong stems are cut into 15 cm sections with 3–4 nodes, and the base is shaped into a horseshoe shape. Soaking in fulvic acid solution for 10–20 minutes helps promote root development and prevent bacterial infection. Cuttings are then planted in sandy loam seedbeds, where the ground temperature ranges from 16–23°C and air temperature is 20–28°C. Roots typically appear within 30 days, after which the plants can be transplanted.
For site preparation, choose open or protected areas with good drainage and irrigation. Apply 3,000 kg of organic fertilizer per 667 square meters, plow deeply, and create raised beds 1.3 meters wide and 6–8 meters long. Plant two rows per bed, with 65 cm between rows and 20 cm between plants, resulting in about 11,000 plants per 667 square meters. Choose sunny locations and water immediately after planting.
Field management includes loosening the soil twice after planting, removing weeds, watering every 10 days to maintain moisture without overwatering, and draining excess water after heavy rains. Fertilize with 200 kg of active chicken manure per 667 square meters after 15 days, and apply 100 kg of the same or 15 kg of compound fertilizer every 15 days during harvest. Additionally, spray 0.2% potassium dihydrogen phosphate every 7–10 days for 3–5 times.
Support structures like plastic ropes or bamboo frames help guide the vines upward, allowing for better space utilization and plant growth.
Harvesting begins when the plant reaches 40 cm in height, with regular picking of shoots and young leaves. It can be sold in bundles or boxes, with a harvesting period lasting over six months. Yield is approximately 3,000 to 4,000 kg per 667 square meters.
Nutritionally, 100 grams of edible portion contains 4.8 g of protein, 0.7 g of fat, 170 mg of calcium, 47 mg of phosphorus, 3.9 mg of iron, 6.7 mg of vitamin A, 503 mg of potassium, 19.6 mg of sodium, 61.6 mg of magnesium, 0.4 mg of copper, 0.3 mg of zinc, 1.19 mg of manganese, and 0.83 mg of cesium—ranking among the top vegetables like cucumber, eggplant, tomato, and spinach.
The longevity vegetable supports immune function, enhances disease resistance, delays aging, increases platelets, stops bleeding, fights cancer, lowers blood sugar, promotes digestion, aids in urination, stimulates milk production, detoxifies, and prevents night blindness.
In cooking, it can be used in salads, stir-fries, fillings, or soups. For example, it can be boiled first, then dressed with garlic, salt, MSG, and sesame oil for a tasty salad; stir-fried with sea cucumbers and mushrooms; made into soft fillings after boiling; or added to soups with glutinous rice or eggs, offering a smooth and fresh taste.
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