How to Propagate Forsythia? A Detailed Guide to the Latest Propagation Methods
Forsythia is also known as Huanghua Tiao, Lian Ke, Qing Qiao, Luo Qiao, Huang Qi Dan, and others. It is a deciduous shrub of the genus Forsythia in the family Oleaceae. Its fruit can be used as medicine. It can be propagated by seeds, cuttings, layering, division, and other methods. In production, seed propagation and cutting propagation are the main methods. Below, let us take a look at the propagation methods of forsythia together!
Division Propagation
After “Frost's Descent” or before spring bud break, dig out the young shoots growing beside trees more than 3 years old together with soil and transplant them, or dig out the entire tree for division and transplanting. Generally, one plant can be divided into 3—5 plants for replanting. The key to using this method is to ensure that each small divided plant has a few fibrous roots, so the survival rate is high and results are quick.
Layering Propagation
Layering propagation involves burying the drooping branches of the plant into the soil in spring, then cutting them from the mother plant and planting them in the following spring.
Cutting Propagation
1. Cutting time: Cuttings can be taken after leaf fall in autumn or before bud break in spring, but spring is better. In the south, cuttings are mostly taken in the open field in early spring, while in the north, cuttings are mostly taken in summer.
2. Cutting treatment: Select robust young branches 1-2 years old, cut them into 20—30 cm long cuttings. The upper cut should be 0.8 cm from the first node. Each cutting must have 2-3 nodes. Then cut the lower end near the node into a flat surface. To improve the cutting survival rate, divide the cuttings into bundles of 30—50 and soak the base of the cuttings (1-2 cm) in 500 ppm ABT rooting powder or 500—1000 ppm indolebutyric acid solution for 10 seconds. Remove and dry them before planting.
3. Cutting method: Before taking cuttings, rake the seedbed fine and level it, make a high bed 1.5 m wide, and insert the cuttings diagonally into the bed at a row spacing of 20×10 cm, with a depth of 18-20 cm in the soil. Leave the topmost node of the branch exposed above the ground, then cover with soil and press firmly. In dry weather, water frequently to keep the soil moist, but not too wet, otherwise the part of the cutting in the soil will turn black and rot. With normal management, the cutting seedling rate can reach as high as 90%. With strengthened field management, the seedlings can reach more than 50 cm in height after autumn, and can be planted in holes in the following spring.
Seed Propagation
1. Seed collection: Select superior mother plants. Choose superior individual plants that grow robustly, have short and thick branches, dense and plump flowers and fruits, no pests or diseases, and pure variety as mother trees. Observe the flowering and fruiting periods carefully and grasp the suitable seed collection time. Collect promptly to avoid seeds falling off by themselves after maturity. Generally, mature fruits are collected from mid-to-late September to early October. Collect fully developed forsythia fruits that are plump, large, and heavy, then spread them thinly in a ventilated and shaded place, and thresh them after drying in the shade. After careful selection and removal of impurities, choose neat, plump seeds free of pests and diseases and store them for seed.
2. Seed storage: Storing forsythia seeds under different conditions greatly affects their germination rate, such as storage in a desiccator being high.
3. Sowing time: Forsythia seeds germinate easily. It should be said that the seeds are suitable for germinating at relatively high temperatures. Based on seed storage and germination conditions, combined with practical experience, the cultivation time can be arranged in spring or winter. Spring sowing is in early-to-mid April, and winter sowing is carried out before the soil freezes.
4. Seed treatment: The seed coat of forsythia seeds is relatively hard. Without pretreatment, direct sowing in the nursery field requires more than 1 month before germination and emergence. Therefore, germination promotion treatment can be carried out before sowing. Newly introduced areas can use this method. The specific method is to select mature and plump seeds, soak them in warm water at about 30°C for about 4 hours, remove them, mix them with 3 times their volume of wet sand, place them in a wooden box or small vat, cover the top with plastic film, and place them in a sheltered, sunny place. Turn them twice a day and keep them moist regularly. After more than 10 days, the seeds sprout and can be sown.
5. Sowing method: After sowing, seedlings emerge in 8—9 days, about 20 days earlier than seeds without pretreatment. If the land is dry, water the bed first, and sow when the water has seeped down and the surface soil is slightly loose. Spring sowing is around “Qingming”, and winter sowing is before the soil freezes (seeds do not need treatment and can emerge the next year). When sowing, on the leveled bed surface, open furrows 1 cm deep at a row spacing of 20-25 cm, mix the seeds with fine sand, evenly scatter them into the furrows, cover with soil, rake level, and press lightly.
6. Post-sowing management: Seedlings can emerge in 10-15 days. The seeding rate is about 2-3 kg per mu. The soil covering should not be too thick, generally about 1 cm, and then cover with grass to keep moist. After the seeds emerge, remove the grass immediately. When the seedlings are 10 cm tall, thin them to a plant spacing of 10 cm. In early April of the following year, when the seedlings are about 30 cm tall, they can be transplanted to the field.
7. Direct field sowing: Open holes at a row spacing of 2 m and a plant spacing of 1.5 m, apply compost and plant ash, mix with soil, and begin sowing from late March to early April. It can also be sown before the soil freezes in late autumn. Sow more than 10 seeds per hole, cover with soil after sowing, and press lightly. Note that sowing should be done when the soil moisture is good.