Detailed Explanation of Cutting Propagation Methods for Japanese Yew in Courtyard

Japanese yew, also known as zi shan or chi bai song, is a precious medicinal and ornamental tree species. The taxol it contains is the most effective anticancer drug in the world today. It stays evergreen year-round, and its peculiar red fruits contrast beautifully with the green leaves, giving it an elegant, refined look with strong ornamental value. Japanese yew can also release various alkaloid gases that kill bacteria and purify the air, providing certain health benefits. It has broad prospects for development in landscaping, bonsai making, and creating green indoor spaces.

The author conducted cutting propagation experiments in a courtyard to cultivate seedlings for bonsai and afforestation. The cutting propagation situation is summarized as follows.

1 Characteristics of Cutting Propagation

Compared with seedling-grown plants, cutting propagation has the following characteristics.

1.1 Early flowering and fruiting

Because the cuttings are taken from large trees, they carry the genes of large trees. The seedlings cultivated have the same medicinal components as the large trees, and they flower and fruit early, giving them high value for medicinal use and as bonsai.

1.2 Fast to reach out-planting stage

Cuttings are 15cm long, inserted 5cm deep. After rooting, the seedlings can reach 10cm in height in the same year. From the 2nd to 4th year, the maximum annual growth of the plants can reach 15cm, and the maximum height at 4 years is 50cm, so they reach the out-planting stage quickly.

1.3 Diverse tree forms

Cutting-propagated seedlings have diverse tree forms that can meet different needs. Among the tree forms, the fan type accounts for the majority, while the clump type and natural open-center type account for the minority.

1.3.1 Fan type: The main branches and side branches spread out in 2 directions on 1 plane.

1.3.2 Clump type: There is no main branch; multiple branches emerge from the root.

1.3.3 Natural open-center type: The main branches and side branches spread out in all directions.

2 Cutting Methods

2.1 In nutrient boxes

Use 12x12cm plastic nutrient boxes, with a substrate of humus soil mixed with a small amount of fine river sand. Arrange 10 boxes per row to form a rectangular nutrient box bed.

2.2 In flower boxes

Use flower boxes with a diameter of 16-20cm, with a substrate of humus soil mixed with fine river sand. Arrange 6-8 pots per row to form a rectangular flower pot bed.

2.3 In open ground

Choose a relatively wind-sheltered, sunny location with good drainage and convenient management. Dig the soil 20cm deep, remove debris, rake it fine, then make a bed. The bed height is 15-20cm and the width is 1-1.2m. Spread more than 5cm of fine river sand on top, mix evenly with the soil at 1:1, and level the bed surface.

Water the substrate thoroughly. Disinfect the soil while watering by adding carbendazim (5-8g/sq m) or potassium permanganate. These tasks should be completed 6 days before cutting.

3 Selection and Treatment of Cuttings

Lignified branches 1-3 years old can all be used as cuttings, among which 1-2 year old branches have the best rooting rate. Perennial reddish-brown branches can also be used for cuttings, but the rooting rate is low. Both main branches and side branches can be used as cuttings.

Branches collected before spring cutting should be kept moist to prevent dehydration from wind and sunlight.

Cut the branches into 15cm-long cuttings. Shorter ones are also acceptable, but short cuttings affect the time to reach the out-planting stage. Remove the leaves 3-5cm from the insertion end, tie them into bundles of 50 cuttings each. When tying, make sure to align the insertion ends and bundle cuttings of equal length together. After tying, place them into the treatment solution promptly.

Soak the insertion ends in Suinong Chunlu solution, diluting each packet with 7.5kg of water. The water temperature should not be lower than 5°C. Stand the bundles upright for soaking, with the soaking depth not exceeding 3cm, and soak for 12-18 hours.

4 Cutting Method

Carry out cutting in late May to early June at the transition between spring and summer. Insert 3-5cm deep. Insert only 1 cutting per nutrient box or flower pot; in the ground, the plant spacing and row spacing are 5x10cm. Insert a knife tip into the soil to pry open a narrow slit, then place the cutting in and press firmly with your hand. Cuttings of the same tree age and equal length should be inserted separately in the same bed. Evenly pour the root-soaking solution onto the seedling bed (in nutrient boxes, in flower pots), then water thoroughly. Note that there should be no standing water on the seedling bed.

5 Heat Preservation, Moisture Retention and Shading

Place bamboo strip arches on the bed surface. The distance between the top of the arches and the bed surface is 50-60cm. Cover the arches with plastic film, and cover the film with a 70% shading-rate plastic shade net, weighing down the edges with bricks. For cuttings in flower pots, if the quantity is very small, insert branches into each pot as arches, put on white plastic convenience bags, and place them under tree shade.

6 Growth and Development of Cuttings

At 15-18 days, the insertion ends thicken and root nodules begin to appear. Some insertion ends rot, but root nodules can still grow above the rotted part. At around 28 days, root nodules generally form. At 30-45 days, roots form in large numbers; the roots are white and thick, commonly called water roots. When roots first form, there are only 1-2, and they gradually increase afterward. Roots grow on the root nodules. Some cuttings form roots in 2 places, with the other place at the soil surface. At 70-80 days, some roots reach 50mm in length, some have just rooted, and a few root only after about 100 days. Some cuttings grow root nodules but do not root. Of the cuttings that do not grow root nodules, some have leaves turn yellow and branches dry up at around 30 days; some dry up only after 10 months. If managed well, the rooting rate can reach over 90%.

7 Post-Cutting Management

Water timely and in appropriate amounts to keep the cutting substrate moist. The water flow should not be too strong when watering, to prevent washing out the cuttings. Excessive water easily causes cuttings to rot. If using tap water for irrigation, it must be stored for more than 4 days before use. When the midday temperature remains too high, cooling can be achieved by uncovering the film and spraying water or by spraying water outside the film.

After extensive rooting, ventilate to harden the seedlings. First uncover one end of the film for ventilation and hardening, for about 2 hours per day. After 3-4 days, uncover both ends of the film for ventilation and hardening, and extend the hardening time day by day. In late August, the plastic film can be removed. After rooting, watering must not be neglected. If the cutting substrate dries out, the seedling root system easily dries up and dies.

8 Overwintering Management

In early November, take heat-preservation and cold-protection measures. First water once, then build a low frame (slightly higher than the seedling height) and cover it with straw bag pieces. If straw bag pieces are placed directly on the seedling bed, the seedlings will freeze stiff and be easily broken.

9 Management After 1 Year

In the 2nd year, there is no need to cover with plastic film. Only use a plastic shade net with a 50% shading rate for shade and carry out routine management. In winter, no cold-protection measures are needed.

From the 3rd year onward, no shading is needed, and normal management is carried out under full light. After 3-4 years of management, saplings 30-50cm tall can be cultivated.