Detailed Explanation of Dogwood Seedling Propagation Methods and Techniques

Dogwood (Cornus officinalis) is a famous medicinal tree species in our country. Its fruit peel contains various amino acids, trace elements and vitamins, and has the functions of warming and tonifying the liver and kidneys, consolidating essence and stopping sweating. In addition, dogwood has bright yellow flowers in early spring, verdant green leaves in early summer, abundant red fruits in autumn, and flourishing branches in winter, making it an excellent urban and rural landscaping tree species.

Dogwood is a deciduous small tree, with a tree height of 3 m to 5 m, a flowering period from late February to early April, blooming before leafing out, and fruits maturing from September to October, generally red when mature, with a few varieties being greenish-white. Dogwood grows best in deep, fertile, loose, organic-rich sandy loam soil with a pH value between 5.0 and 6.5. Dogwood is relatively shade-tolerant but also prefers sufficient light. It can be planted on shady slopes and semi-shady slopes, and in high-altitude areas, sunny slopes can be selected for planting.

Seed propagation

Select excellent seed-bearing mother trees that grow vigorously and are free of pests and diseases, and begin collecting when the seeds are fully mature around September. From the collected fruits, select fruits that are large, brightly colored, and have plump seeds, and sun-dry them for 3 days to 4 days. After they become soft, peel off the flesh and dry them for use as seeds.

Dogwood seeds have a deep dormancy characteristic. The seed stone is hard and contains a transparent mucilaginous resin that is impermeable to water and air, affecting seed germination. If sown directly, seedlings often do not emerge until the second or even third year. Therefore, seed pregermination must be carried out before sowing. Treatment methods include chemical treatment, stratification pregermination, human feces and urine composting, and nursery surface burning.

Select flat terrain, fertile soil, and well-drained sandy loam as the nursery site. In winter, apply sufficient base fertilizer and plow deeply. Farmyard manure and plant ash are best for base fertilizer. Before spring seedling raising, shallow plowing and raking level, then prepare the land into beds. For nursery land prone to underground pests such as mole crickets and white grubs, soil disinfection should be carried out when preparing the land into beds.

Sowing is divided into autumn sowing and spring sowing, with spring sowing mostly used in production. Spring sowing is usually carried out from February to March after the soil thaws, and autumn sowing is mostly carried out from September to November before the soil freezes. Use the drill sowing method, with a row spacing of 20 cm to 30 cm and a furrow depth of 4 cm to 5 cm. After watering in the furrow and sowing, cover with soil 2 cm to 3 cm, and cover with wet grass on top.

Seedlings can emerge about 25 days after sowing. When 70% of the seedlings have emerged, remove the covering grass on the seedbed in 2 to 3 batches. During the seedling growth period, loosen the soil, weed, and control pests and diseases in a timely manner. When the seedlings are more than 10 cm tall, thin and finalize the seedlings. When they reach 20 cm, apply an appropriate amount of fertilizer. After the seedlings enter the rapid growth period in July, strengthen fertilizer and water management. Entering September, to accelerate lignification, stop applying nitrogen fertilizer and increase the application of phosphorus and potassium fertilizers. When the current-year seedlings reach 60 cm to 100 cm in height, they can be released from the nursery.

Vegetative propagation

When dogwood is afforested with seedlings grown from seed, only 6-year-old seedlings can bloom and bear fruit, whereas afforestation with vegetatively propagated seedlings can maintain the excellent traits of the mother plant, and generally they can bloom and bear fruit in 4 years. Common vegetative propagation methods include cuttings, grafting, and layering.

Cuttage propagation: Generally choose April to May. From excellent-type mother trees, select vigorous, pest-free one- to two-year-old branches, cut them into 15 cm to 20 cm long cuttings, cut the upper incision flat and the lower incision slanted, retain about 4 leaves on the cutting, and cut off all the remaining leaves and petioles. Use a mixture of humus and fine sand in equal proportions as the cutting bed. Open furrows on the cutting bed at a row spacing of 20 cm, and insert cuttings in the furrows at a plant spacing of 8 cm to 10 cm, covering with soil as you insert. After inserting, water thoroughly once and cover with agricultural film. Remove the agricultural film in mid-June, set up a shade frame with 10% light transmittance, and after about 90 days to 100 days they can root and survive.

Grafting propagation: Dogwood is generally grafted using seed-grown seedlings, and tree species of other genera in the same family as dogwood, such as Cornus wilsoniana, Cornus controversa, and Cornus kousa, can be used as rootstocks. The seed-grown seedlings used as rootstocks are best when one to two years old with a ground diameter of 0.6 cm to 1 cm. Select excellent-type middle-aged mother trees with vigorous tree vigor and no pests or diseases, collect fully developed one-year-old branches from the middle-upper part or periphery of the crown, cut them into 10 cm to 15 cm lengths, and seal the upper and lower incisions of the scions with paraffin. After sealing with wax, store the scions in a low-temperature place for later grafting. The suitable grafting period is from April to September.

Layering propagation: Every year in October in autumn, select excellent-type mother trees that grow vigorously and are about 10 years old. Bend branches sprouting around the root collar or branches close to the ground to the ground, and notch them to the xylem at the place where they are to take root in the soil. Then bury them in a 15 cm hole, cover with soil and press firmly, expose the branch tips above ground, fix them on wooden stakes, and strengthen management. When new roots are produced, cut them from the mother plant and plant them out.