Detailed Explanation of Key Techniques for High-Yield Cultivation of Gardenia

Gardenia, also known as mountain gardenia or yellow gardenia, is grown for its fruit, which is used medicinally and for extracting natural pigments. Medicinally, it has the functions of purging fire and relieving restlessness, clearing heat and draining dampness, and cooling blood and removing toxins; the natural pigments extracted from its fruit as a raw material are widely used in the food industry and for export. In recent years, demand for gardenia in domestic and international markets has increased rapidly, and the market prospects are very promising. In order to increase gardenia yield and boost economic returns, several main measures for high-yield gardenia cultivation are introduced below:

I. Site Selection and Land Preparation

Selecting a good planting site for gardenia and preparing the land well lays a solid foundation for high gardenia yields. A high-yield gardenia planting site should be chosen on the middle-lower part of a south-facing, east-west oriented sunny slope, or on flat land with deep, fertile, loose, well-drained sandy soil. For barren slope land, full clearing should be carried out in the winter of the previous year, then holes should be dug at a row spacing of 1.5×1.2m or 1.3×1.2m, with each hole 50cm deep and 50cm wide. After weathering through the winter, apply 5kg of decomposed farmyard manure per hole before planting the following spring, mix the soil and fertilizer thoroughly, and wait to plant.

II. Reasonable Pruning and Shaping

After planting, train the gardenia tree into a naturally open-centered shape with a spreading canopy. The specific method: in the first year after planting, remove the sprouts within 20cm of the trunk above ground level as the trunk height. When the shoots grow to 18-20cm, select and keep 3-4 strong branches growing in different directions to develop into main branches. In the summer of the second year, from the leaf axils of the retained main branches, select and keep 3-4 strong secondary branches to develop into sub-main branches growing in different directions, successively extending the terminal shoots. Later, side branches are sent out from the sub-main branches. By the third year, the tree enters the fruiting stage. Through reasonable shaping, the canopy is round outside and open inside, with well-spaced branches, good ventilation and light penetration, which regulates the balance between growth, development, shoot production, flowering and fruiting, reduces useless nutrient consumption, increases the fruiting area and raises yield.

III. Scientific Fertilization

In the first to second years after planting, the plants are in the vegetative growth stage, so fertilization should focus on nitrogen fertilizer, supplemented by phosphorus and potassium fertilizers. Combined with hoeing and weeding, apply fertilizer 3 times per year, in spring, summer and autumn respectively. For the first and second applications, apply 1500-2000kg of human and livestock manure water per 667 sq m each time. For the third topdressing, apply 2000kg of barnyard manure per 667 sq m, placed in a ring trench around the outer edge of the canopy, then cover with soil after application to promote lush canopy growth. Once gardenia enters the fruiting stage, phosphorus and potassium should be the main nutrients, while nitrogen depends on plant growth conditions, in order to improve the fruit-setting rate. Apply 3-4 times per year. The first is spring fertilizer, applied between March and April each year, with 25kg of urea and 50kg of cake fertilizer per 667 sq m. The second is fruit-swelling fertilizer, applied between May and June, with increased phosphorus and potassium fertilizer and controlled nitrogen dosage, applying 50kg of compound fertilizer per 667 sq m, and spraying 75-100kg of a solution of 0.2% potassium dihydrogen phosphate and 1% urea liquid or 3% superphosphate liquid onto leaves, flowers and fruits on a sunny day as foliar topdressing. The third is autumn shoot-promoting fertilizer. More than 95% of the terminal buds of gardenia autumn shoots form flower buds, and autumn shoot flower buds account for more than 85% of fruiting plants, making them the main fruiting branches, so this shoot-promoting fertilizer is particularly important. It is usually applied before the Beginning of Autumn, with 2000kg of barnyard manure mixed with 30kg of cake fertilizer and 5kg of urea per 667 sq m, placed in a ring trench and covered with soil after application, to promote autumn shoot growth and flower bud differentiation. The fourth is applied after fruit harvest, with 2000kg of barnyard manure and grass-sod ash (burnt soil ash) plus 25-30kg of superphosphate per 667 sq m, mixed evenly, placed in a ring trench and covered with soil. This is winter fertilizer, mainly to replenish the large amount of nutrients consumed after fruiting, restore plant vigor, help flower bud differentiation and avoid alternate-year fruiting, thereby enhancing the plant's cold resistance. Among the 4 topdressings, the last 2 are particularly important, and their fertilizer amount still accounts for two-thirds of the total annual fertilizer amount.

During the peak flowering period of gardenia, spray 0.15% borax. When three-quarters of the flowers have fallen, spray a solution with 5g of gibberellin dissolved in every 100kg of water, or a mixed solution with 8-10g of 2,4-D and 0.3% urea and 0.2% potassium dihydrogen phosphate dissolved in every 1000kg of water, once every 10-15 days, for 2 consecutive sprays. This can promote gardenia growth, accelerate cell proliferation and reduce the formation of the fruit stalk abscission layer, thereby increasing the fruit-setting rate.

IV. Timely Harvesting

Whether gardenia is harvested at the right time has a great influence on yield and quality. If harvested too early, when the fruit peel is still green and not yet ripe, the processing drying ratio is low, yield is not high, and quality is poor. If harvested too late, drying is difficult and the fruit is prone to molding during processing, making it not only hard to store but also poor in quality. Therefore, gardenia should be harvested at the right time when the fruit peel turns red-yellow, and harvesting on a sunny day is best. The processed product then not only has a high drying ratio but also excellent quality.