A Detailed Guide to the Latest Methods for Planting Osmanthus Seeds

How do you plant osmanthus seeds? Osmanthus seeds are drupes, elongated oval in shape, with ridges, and generally mature in April to May. When mature, the outer skin turns from green to purplish black, and they fall from the tree. The seeds can be picked from the tree or gathered from the ground, but you must pick them up as soon as they fall, otherwise the dry spring climate will cause the seeds to lose water easily and lose their sowing value. Now let us take a look at the planting methods for osmanthus seeds!

Pre-sowing Treatment of Osmanthus Seeds

1. Seed preparation: After osmanthus seeds are collected, they must be prepared immediately. The outer seed coat of mature fruit is relatively soft, so it can be washed immediately with water. Wash the fruit skin clean, remove the empty and small seeds floating on the water surface, pick out impurities, and then place them indoors in the shade to dry. Be careful not to dry them in the sun, because osmanthus seeds have no waxy layer on the seed coat, so they lose water very easily and become shriveled, thereby losing their physiological activity.

2. Seed storage: Osmanthus seeds have the characteristic of physiological after-ripening, and must undergo proper storage and germination acceleration before they can be sown and raised as seedlings. Osmanthus seed storage generally has two methods: sand storage and water storage.

① Sand storage means covering them layer by layer with wet sand. The site for sand storage of seeds is best in a cool, ventilated place, and they should be piled on soil or sandy soil, not on concrete ground.

② Water storage means putting the seeds in a bag that is breathable but not easily rotted, tying the bag opening tightly, and placing it in cold water, preferably running water. Check frequently to see whether the seeds have lost water or become moldy and deteriorated. The seed bag for water storage should not be exposed above the water surface. In summer, the seed bag should be kept away from the high-temperature water layer near the water surface, so as to prevent the seeds from germinating and rotting from heat.

3. Seed inspection and disinfection

① Inspection: Before sowing, seed inspection should be carried out, removing empty-shelled seeds and deteriorated seeds. Then use a small knife to randomly cut open several plump seeds and observe whether the seed kernel is fresh and whether it has viability. Generally, the seed kernel of good seeds is milky white.

② Disinfection: First wash the seeds clean with clear water, then place them in a 0.5% potassium permanganate or 1% bleaching powder solution and soak for 15 to 20 minutes, then filter out the residual disinfectant liquid and residue. After the seeds are rinsed with clear water, dry them and sow; or soak the seeds in a 0.5% formalin solution for 15 minutes, pour off the liquid, seal and fumigate the seeds for half an hour, then rinse with clear water, dry, and sow.

4. Germination acceleration treatment: In order to make the seeds germinate quickly and uniformly, the disinfected seeds can be placed in warm water at about 50°C and soaked for 4 hours, then taken out and put into a bamboo basket, covered with a wet cloth or straw, and placed under a temperature condition of 18 to 24°C for germination acceleration. When half of the seeds have cracked seed coats or slightly exposed radicles, they can be sown. During the germination acceleration process, the seeds should be turned frequently so that the temperature and humidity of the upper and lower layers remain consistent, so that germination is uniform.

Sowing Methods for Osmanthus Seeds

From early February to April of the following year, when the seeds crack open and show white, they can be sown and raised as seedlings. The drill sowing method is generally used, that is, making horizontal or vertical furrows on the seedbed, with a furrow width of 12 cm and a furrow depth of 3 cm; in the furrow, sow 1 pregerminated seed every 6 to 8 cm. When sowing, place the hilum side facing sideways, so as to avoid bending of the radicle and young stem, which would affect the growth of the seedlings. In the Guilin area, wide-row drilling is usually used, with a row spacing of 20 to 25 cm and a width of 10 to 12 cm, sowing 20 kg per mu, which can produce 25,000 to 30,000 seedlings.

After sowing, cover immediately with fine soil. The thickness of the covering soil should preferably not exceed 2 to 3 times the transverse diameter of the seed; after covering with soil, level the bed surface to avoid water accumulation; then cover with a thin layer of straw, to the extent that the soil is not visible, and stretch ropes to press it down to prevent the covering straw from being blown away by the wind; then use a fine-spout watering can to spray water fully until the soil is thoroughly wet. Covering with straw and spraying water can keep the soil moist, avoid soil crusting, and promote early seed germination and early emergence.

Post-sowing Management of Osmanthus Seeds

After the seeds germinate, management work should follow promptly in order to cultivate robust seedlings. For the growth and development of the seedlings, the following six points should be done well in specific operations:

1. Removing the covering and shading: After the seeds germinate and emerge from the soil, the covering should be properly removed on cloudy days or in the evening. Removing the covering too early fails to achieve the purpose of covering; removing it too late may break the young sprouts or form leggy seedlings. Removing the covering should be done in stages, and part of the covering can be left between the seedling rows to keep the seedbed moist, reduce water evaporation, and prevent weed growth. After the covering is removed, as the high-temperature summer season arrives, shade frames should be built in time, keeping the light transmittance of the shade frame at about 40%. The daily shading time is generally covering in the morning and removing in the evening; covering on sunny days and removing on cloudy and rainy days. By early to mid-September, the reed curtains used for shading can be collected and stored.

2. Loosening the soil and weeding: Loosening the soil should be carried out in time, with a depth of 2 to 3 cm; it should be shallow rather than deep, to prevent damaging the roots. Weeding can be combined with loosening the soil, striving to weed early, weed small, and weed thoroughly. In addition, weeds along ditches, paths, and field ridges should also be removed completely, so as to clean the nursery land and eliminate breeding places for diseases and pests.

3. Thinning and filling in seedlings: Osmanthus seedlings are relatively shade-tolerant and slow-growing, so thinning is generally unnecessary; appropriately moving dense seedlings to fill gaps is sufficient. When moving seedlings, do not damage the root system of the retained seedlings. After moving seedlings, irrigate once so that the seedling roots and soil are closely combined.

4. Irrigation, drainage, and fertilization: In drought seasons of summer and autumn, attention must be paid to drought resistance and seedling protection. Irrigation is best carried out in the morning or evening. Use a quick-irrigation, quick-drainage method; water thoroughly and evenly. In the rainy season, strengthen ditch clearing and drainage to avoid waterlogging of the seedlings. One month after the seedlings emerge, they enter the period of vigorous growth. Each month, apply once a thoroughly decomposed dilute stable manure liquid or nitrogen fertilizer. The concentration is 10 kg of stable manure liquid or 150 to 200 g of urea or 300 to 400 g of ammonium sulfate mixed with every 100 kg of water. As the seedlings grow, the fertilization concentration can be appropriately increased. After autumn begins, stop topdressing to prevent excessive vegetative growth of the seedlings and freezing damage. When topdressing, do not let the fertilizer liquid adhere to the seedlings, so as to avoid injuring them.

5. Pest and disease control: Nurseries with continuous cropping of osmanthus are prone to brown spot disease and damping-off disease, causing large numbers of leaves to turn yellow and fall off, or the root collar and root cortex of the seedlings to rot, leading to death of the whole plant. At the same time, aphid damage is also likely to occur during the seedling stage. Therefore, pest and disease control work cannot be ignored.

6. Timely transplanting: One-year-old sown osmanthus seedlings are 20 to 30 cm tall and are transplanted in early spring of the following year. Two-year-old seedlings are about 60 cm tall. When three-year-old seedlings are about 1 m tall, another transplanting is required. For use as courtyard shade trees or trunk-road trees, cultivation is generally required for 8 to 10 years, with a height of 2 to 3 m and a diameter of 8 to 10 cm, which is conducive to maintenance and management after planting.