Platycodon grandiflorum, commonly known as the balloon flower, can be propagated through seeds or by using the root head (rhizome or reed head). Among these methods, seed propagation is currently the most widely used. In practical cultivation, there are two main approaches: direct seeding and transplanting seedlings. Direct seeding is preferred because it results in higher yields, fewer branches, easier processing, and better quality. This method is widely adopted in commercial production. 1. Seed Propagation (a) Seed Characteristics 1. The seeds of Platycodon grandiflorum are obovoid in shape, with five small petals at the top. When mature, they turn brown and contain a large number of seeds. Each seed is obovate or elongated obovate, with a wing on one side. Their dimensions range from 2.0 to 2.6 mm in length, 1.2 to 1.6 mm in width, and 0.6 to 0.8 mm in thickness. The surface is brown or dark brown, shiny, and under a microscope, dark vertical lines can be observed. The umbilicus is located at the base, forming a pit-like structure. The wings are 0.2 to 0.4 mm wide and often lighter in color. The endosperm is white and translucent, containing oil. The embryo is small and straight, with two cotyledons. The thousand-seed weight ranges from 0.93 to 1.4 grams. 2. Storage and Viability: Fresh seeds should be used within the same year for best results. New seeds germinate quickly, have a high germination rate, and produce uniform, strong seedlings that are easy to manage. Seeds stored for more than a year tend to have lower germination rates. For example, after 17 months of storage, the germination rate dropped to 68.35%, and after 30 months, it was only 33.6%. According to historical records, seeds stored in paper bags in Nanjing for over two years still had some viability, but their germination rate significantly declined. Studies from 1936 suggest that under normal storage conditions, the lifespan of Platycodon seeds is typically 1 to 2 years. 3. Germination Conditions: The seeds do not require strict temperature conditions for germination, as they can sprout between 15°C and 30°C, with an optimal range of 15°C to 25°C. Gibberellin has been shown to enhance germination when used at concentrations between 50 and 200 ppm. Additionally, ultrasonic treatment—such as 250W power at 20,000Hz for 13 minutes—can increase the germination rate by up to 2.1 times compared to untreated seeds. 4. Seed Selection Tips: (1) Distinguish between fresh and old seeds. Fresh seeds have a germination rate of about 70%, while older seeds have significantly lower viability. A simple test before sowing can help determine the germination rate. Fresh seeds are oily and shiny, whereas old seeds are dry and dull in appearance. (2) Avoid purchasing “doll species,†which are actually seeds of annual plants. These seeds are thin, light-colored, and produce weak seedlings. It’s best to use seeds from two-year-old plants, which are larger, plumper, and have a higher germination rate. Using such seeds can result in yields that are over 30% higher than those from inferior seeds. 2. Sowing Methods: Seeds can be sown in spring, autumn, or winter, with autumn being the most favorable. Autumn-sown seeds emerge in the same year, allowing for a longer growth period and better yield and quality. In northern regions, autumn sowing is usually done in mid-October, winter sowing in early November, and spring sowing between late March and mid-April. In practice, shallow furrows are created every 20–25 cm, with a depth of 2–3 cm. Seeds are sown evenly, and mixing them with fine sand (1:10 ratio) helps distribute them more evenly. After sowing, the soil is lightly covered and pressed. In some areas, fire ash is used to cover the seeds. If the soil is dry, watering is necessary to keep it moist. The recommended seed rate is 0.5–0.8 kg per acre. Germination typically occurs within 2 weeks after autumn sowing. To speed up germination, seeds can be soaked in warm water (50°C) until it cools down, then left to soak for 8 hours. They are then wrapped in wet cloth and kept at 25–30°C. Water is added daily until they sprout, which usually takes 4–5 days. Alternatively, soaking seeds in a 0.3–0.5% potassium permanganate solution for 24 hours can also improve germination rates. Afterward, rinse and dry the seeds before planting. 3. Transplanting Seedlings: Seedlings are usually transplanted in March. They are grown in sunny, wind-shielded areas with well-prepared beds. The seedbeds are 120 cm wide and 15–20 cm high. Shallow furrows are made at 15 cm intervals, and seeds are sown using the broadcasting method. Before planting, the seeds are treated and germinated. A mixture of ash and manure water is added to the furrows, and the soil is covered with 0.5–1 cm of fertile soil. Grass is placed on top to retain moisture and prevent erosion. About 10–15 days after sowing, thinning is required. When the seedlings reach 1.5 cm in height, weak ones are removed. At 3 cm, they are spaced 3–4 cm apart, and proper care is taken, including weeding, watering during dry periods, and fertilizing to support growth. By the time of the next growing season, the plants are ready for transplanting. This method is efficient, saves labor, and is ideal for large-scale farming, though it may not develop a strong main root. 4. Root Head Propagation: Root head propagation can be done in spring or autumn, with autumn being the preferred time. During harvest, healthy, disease-free plants are selected, and the roots are cut just below the top of the reed. Mixing them with fine ash before planting helps prevent rot and stimulates callus formation, making rooting easier. Sandy loam soil with good drainage is ideal. The field is prepared by digging 30–40 cm deep, leveling the soil, and creating mounds 1.5 meters wide and 20–25 cm high. Horizontal furrows are dug 10 cm deep and spaced 10 cm apart. Each furrow receives 2–3 kg of human manure water, followed by a layer of soil and composted organic fertilizer (about 3000 kg per mu). This ensures proper moisture, insulation, and nutrients for the emerging plants. By the second spring, each plant typically produces 2–3 shoots. candy， vegan candy Montreal Shantou Food Co., Ltd , https://www.montrealsnack.com
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