How to propagate Spiraea japonica? Detailed introduction to propagation methods
Spiraea japonica (detailed introduction) has pink flowers and a certain ornamental value, and artificially cultivating Spiraea japonica is not very difficult. Because Spiraea japonica is widely used in gardens, market demand for it is also growing. Generally, sowing, division and cuttings can be used for propagation.
Spiraea japonica
I. Propagation by sowing
After the seeds mature in autumn, pick them, dry them in the sun, thresh them and store them. The following spring, take the seeds out and sow them in pots. Because the seeds are very small, sowing propagation requires careful attention. Before sowing, first soak the potting soil thoroughly with water, then evenly scatter the seeds, cover with a layer of sifted fine soil, and afterward pay attention to moisture retention; seedlings emerge in about 1 month. The row spacing of sown seedlings is 50-60 cm, preferably in a north-south row direction, with 2-3 cm of covering soil. In addition, because sown seedlings are prone to damping-off, spray Bordeaux mixture before the disease occurs for control.
II. Propagation by division
Generally, in February-March, combine with transplanting, separate the suckers from the mother plant, prune appropriately and then plant separately. You can also fertilize the soil before division to encourage the mother plant to produce more suckers, then dig them up and plant separately the following year.
III. Propagation by cuttings
In theory, both softwood and hardwood of Spiraea japonica can be used for cuttings, but softwood cuttings are clearly better than hardwood cuttings, so in most cases softwood cuttings are selected.
Spiraea japonica L. f. Spiraea japonica illustrated guide: how to grow Spiraea japonica / how to propagate Spiraea japonica
Spiraea japonica profileSpiraea japonica L. f.
Aliases: Mahuangshao, Huoshaojian, Japanese spiraea
Classification: shrub flower
Family and genus: Plantae, Angiosperms, Dicotyledons, Rosales, Rosaceae, Spiraea
Full bloom period: summer
Spiraea japonica, also known as Mahuangshao, Huoshaojian and Japanese spiraea, is an upright shrub in Rosaceae, Spiraea, up to 1.5 m tall; branches spreading, slender, cylindrical, winter buds ovate, leaves ovate to ovate-elliptic, dark green above, lighter or glaucous beneath, usually with short pubescence along the veins; compound corymb, flowers dense, densely pubescent; bracts lanceolate to linear-lanceolate, calyx tube campanulate, sepals triangular, petals ovate to rounded, pink; disk annular, follicles half-open, styles terminal. Sometimes it blooms twice. Spiraea japonica is native to China, has strong ecological adaptability, is cold-tolerant, drought-tolerant, barren-tolerant...
How to grow Spiraea japonica and precautions Introduction to Spiraea japonica
Spiraea japonica, also known as Mahuangshao, Huoshaojian and Japanese spiraea, is an upright shrub in Rosaceae, Spiraea, up to 1.5 m tall; branches spreading, slender, cylindrical, winter buds ovate, leaves ovate to ovate-elliptic, dark green above, lighter or glaucous beneath, usually with short pubescence along the veins; compound corymb, flowers dense, densely pubescent; bracts lanceolate to linear-lanceolate, calyx tube campanulate, sepals triangular, petals ovate to rounded, pink; disk annular, follicles half-open, styles terminal. Sometimes it blooms twice.
Spiraea japonica is native to China and has strong ecological adaptability, tolerating cold, drought and barren conditions and resisting pests and diseases. It is widely used in various green spaces and can be used as a groundcover flowering plant, flowering hedge and flower border. With abundant flowers and dense leaves, it has ornamental value and can be used as a landscaping plant.
Spiraea japonica blooms from June to July and fruits from August to September.
Morphological characteristics of Spiraea japonica
Spiraea japonica is an upright shrub, up to 1.5 m tall; branches slender, spreading, branchlets nearly cylindrical, glabrous or short pubescent when young; winter buds ovate, apex acute, with several scales.
Leaves ovate to ovate-elliptic, 2-8 cm long, 1-3 cm wide, apex acute to shortly acuminate, base cuneate, margin incised doubly serrate or simply serrate, dark green above, glabrous or slightly short pubescent along the veins, lighter or glaucous beneath, usually short pubescent along the veins; petiole 1-3 mm long, short pubescent.
Compound corymb borne at the apex of upright new shoots of the current year, flowers dense, densely short pubescent; pedicels 4-6 mm long; bracts lanceolate to linear-lanceolate, slightly pubescent beneath; flowers 4-7 mm in diameter; calyx sparsely short pubescent outside, calyx tube campanulate, short pubescent inside; sepals triangular, apex acute, short pubescent inside near the apex; petals ovate to rounded, apex usually rounded-obtuse, 2.5-3.5 mm long, 2-3 mm wide, pink; stamens 25-30, much longer than the petals; disk annular, with about 10 irregular lobes.
Follicles half-open, glabrous or sparsely pubescent along the ventral suture, styles terminal, slightly spreading obliquely, sepals often erect.
Spiraea japonica flowers from June to July and fruits from August to September.
Ecological habits of Spiraea japonica
Spiraea japonica likes light, and with ample sunlight it produces a large number of flowers; it tolerates partial shade; it is strongly cold-tolerant and can withstand low temperatures of -10 °C; it likes a temperate climate with four distinct seasons and grows poorly in subtropical and tropical areas without obvious alternation of the four seasons; it tolerates poor soil but not wetness, and grows luxuriantly in moist, fertile soil rich in organic matter. It needs more water during the growing season, but does not tolerate waterlogging, and also has a certain drought tolerance.
Cultivation techniques for Spiraea japonica: land preparation and bed making
Deeply turn and loosen the soil. Generally, dig the nursery land 15-20 cm deep, level it carefully, compact it, and remove debris. When making beds, disinfect the soil. Make beds along a north-south direction; generally choose flat beds, bed length 40 m (about 20 m is also acceptable), bed height 10-20 cm, bed height 0.1 plus .15 m, bed width 1-2 m, path width 50 cm, to facilitate weeding. Water and rake the bed surface level and compact it. Set up reed curtain shade on the cutting bed. If conditions permit, add a layer of base fertilizer (farmyard manure) at the bottom of the bed, and at the same time mix in 1:5000 carbendazim for disinfection. Finally, evenly spread a layer of fine sand on the bed surface, mix fertile loam and river sand at 1:1 as the upper layer of soil for the nursery bed, then water the seedlings thoroughly.
Cutting shoots and cuttings
Collect current-year softwood. From mid-to-late June to early-to-mid July, use cuttings directly from clustered hardwood shoots growing from the rhizome and softwood cuttings growing from hardwood shoots. Cutting length is 10-12 cm, all without terminal buds, cuttings with 4-5 buds, shoot thickness 0.2 cm or more, retain 2-3 nodes of leaves at the upper end, cut to 8 cm long, keep the upper 2 leaves, and remove the lower 2-3 nodes of leaves and the upper flower spikes; the lower part inserted into the soil should have plump buds. Soak the base in rooting powder solution for 3-5 minutes, and insert into the nursery bed before the dog days (the best time is mid-June), with a cutting depth of 3 cm. Soak the base of the cuttings in IBA solution at a concentration of 50-150 mg/L for 24 hours, then insert the cuttings 4-5 cm deep into the bed surface. Cutting spacing is 5-6 cm, density 280-400 plants per square meter. After inserting, spray thoroughly with water so that the cuttings and substrate are closely combined.
Shading and plastic film covering
For open-field cuttings, build a shade shed; 75% shading is sufficient. If taking cuttings under forest, the trees in the forest can be used for shade. After the seedlings are inserted into the nursery bed, cover with plastic film and build it into an arch shape, with an arch height of 60 cm.
Outplanting and transplanting
Transplant in the following spring. Generally, in February-March, combine with transplanting; generally, in February-March, combine with transplanting, separate the suckers from the mother plant, prune appropriately and then plant separately. You can also fertilize the soil before division to encourage the mother plant to produce more suckers. When transplanting, first dig a hole, water, transplant with water, and cover with soil and tread firm. If propagating by cuttings in a greenhouse, cuttings can be taken at any time until autumn, and they can also be outplanted while cuttings are being taken; the following year they can be dug up and planted separately. This method is easy to manage, quick to profit from, convenient and simple, and suitable for promotion.
Planting management
To improve the survival rate of planting, keep a small section of roots when lifting seedlings. If planting seedlings with a ground diameter above 1.5 m in summer, plant with a soil ball, ball diameter 20-30 cm, and prune some branches after transplanting. By thinning branches and heading back, reduce water evaporation from the tree body and promote survival. After the seedlings are inserted, the film should be covered tightly, watered once a day, and sprayed with a fine-nozzle watering can; on cloudy days, water thoroughly once every 2 days. About 15 days after cutting, rooting basically begins. At this time, spray Tuzet once every 7 days, and spraying continuously 2 times is sufficient. If there is continuous rain, pay attention to ventilation, open the film at both ends of the nursery bed for ventilation, and cover it promptly at night.
In addition, prevent waterlogging in the bed; too high humidity is not conducive to rooting. During seedling management. Remove weeds promptly. After the seedlings root, they can overwinter on the cutting bed, covered with straw curtains. Note that the humidity in the shed bed should be kept at 80%-90%, and the temperature below 28 °C. When it exceeds 28 °C, open the plastic film for ventilation and cooling. Rooting begins 30 days after cutting, and at 45-50 days remove the shade net, spray an appropriate amount of water, and keep the soil alternately dry and moist as suitable.
To promote seedling growth, apply diammonium phosphate once to the bed surface, 8-10 L per square meter, and water promptly. Every 10 days, spray 0.3%-0.5% potassium dihydrogen phosphate solution 2-3 times to promote early lignification of the seedlings. For cuttings before and after flowering, the survival rate of hardwood cuttings can reach 70%, and the survival rate of softwood cuttings is generally above 90%. To improve its utilization value, cutting propagation after flowering should be advocated. After rooting, gradually remove the plastic film and shade net, carry out hardening, and transplant in the following spring.
Propagation methods of Spiraea japonica
Spiraea japonica is commonly propagated by division, cuttings or sowing. After flowering, pruning should be carried out to remove the spent flowers.
Sowing
After the seeds mature in autumn, pick them, dry them in the sun, thresh them and store them. The following spring, take the seeds out and sow them in pots. Because the seeds are very small, sowing propagation requires careful attention. Before sowing, first soak the potting soil thoroughly with water, then evenly scatter the seeds, cover with a layer of sifted fine soil, and afterward pay attention to moisture retention; seedlings emerge in about 1 month. The row spacing of sown seedlings is 50-60 cm, preferably in a north-south row direction, with 2-3 cm of covering soil. In addition, because sown seedlings are prone to damping-off, spray Bordeaux mixture before the disease occurs for control.
Division
Generally, in February-March, combine with transplanting, separate the suckers from the mother plant, prune appropriately and then plant separately. You can also fertilize the soil before division to encourage the mother plant to produce more suckers, then dig them up and plant separately the following year.
Cuttings
Both softwood and hardwood can be used for cuttings, and softwood is clearly better than hardwood.
Cutting experiment material: select disease-free, pest-free, robust current-year softwood from 3-year-old Japanese spiraea mother plants at Xianglong Nursery in Bonihe Town, Jiutai City, as cuttings.
Method
1. Experimental method for the effect of different substrates on cutting survival rate
Cut the collected branches into 6 cm lengths, leave 2-3 leaves at the upper part, make the top cut flat and even, and cut the lower cut into a slanted shape. Insert them separately into 4 different substrates: river sand, furnace ash slag, farmland soil, and river sand + sawdust (river sand:sawdust = 3:1), with 30 cuttings as one group, 3 replicates. After 30 days, investigate the rooting rate (number of rooted cuttings / total number of cuttings) and root number (total number of roots of rooted cuttings in each control group).
2. Experimental method for the effect of different concentrations of rooting powder on cutting survival rate
The rooting powder used in this experiment is Luye rooting powder produced by Anhui Wuwei Humic Factory. First dissolve it with a small amount of alcohol (19 rooting powder + 5 g alcohol), then dilute with water into rooting solutions with concentrations of 0, 500, 1500, 2000, 2500, and 3000 mg/kg. Use 30 cuttings as 1 group, 3 replicates, with river sand + sawdust as the cutting substrate. Soak the base of the cuttings in the above concentration rooting solutions for 2 hours before cutting. After 30 days, investigate the rooting rate (number of rooted cuttings / total number of cuttings) and root number (total number of roots of rooted cuttings in each control group).
Management after cutting
After the seedlings are inserted, cover with a plastic film-supported shed, water thoroughly once a day with a fine-nozzle watering can, and pay attention to timely ventilation during afternoon high temperatures and on cloudy and rainy days. Spray carbendazim once a week to prevent disease occurrence, and remove weeds promptly.
Using softwood cuttings for propagation can quickly obtain seedlings. Different substrates and different concentrations of rooting powder all have obvious effects on the branch cuttings of Japanese spiraea. Among different substrates, river sand + sawdust (3:1) as the cutting substrate gave the best rooting, with a rooting rate reaching 94.1%, and an average of 12.6 roots per cutting. Among treatments with different rooting powder concentrations, the concentration of 2000 mg/kg had the best effect, with the rooting rate and number of roots of cuttings being 96.5% and 14.1 roots respectively.
Variety classification of Spiraea japonica: main varieties
This species is highly variable. The following 6 varieties are also produced in China.
Spiraea japonica L. f. var. acuminata Franc
Leaves long ovate to lanceolate, apex acuminate, base cuneate, 3.5-8 cm long, margin sharply doubly serrate, short pubescent along the veins beneath. Compound corymb 10-14 cm in diameter, sometimes up to 18 cm, flowers pink.
Produced in Henan, Shaanxi, Gansu, Hubei, Hunan, Jiangxi, Zhejiang, Anhui, Guizhou, Sichuan, Yunnan, Guangxi. Grows on open hillsides, in sparse or dense mixed woods, in valleys or beside streams, at an altitude of 950-4000 m.
Spiraea japonica L. f. var. acuta Yu
Leaves smaller, elliptic or ovate, apex acute, base broadly cuneate to rounded, 2.5-4.5 cm long, margin sparsely doubly serrate, short pubescent beneath. Compound corymb smaller, 2.5-4 cm in diameter, flowers pink.
Produced in western Yunnan. Grows in mixed woods or on grassy slopes, at an altitude of 2500-2700 m.
Spiraea japonica L. f. var. fortunei (Planchon) Rehd.
This variety is taller, leaves oblong-lanceolate, apex shortly acuminate, base cuneate, margin sharply doubly serrate, 5-10 cm long, wrinkled above, glabrous on both sides, glaucous beneath. Compound corymb 4-8 cm in diameter, flowers pink, disk not developed.
Produced in Shaanxi, Hubei, Shandong, Jiangsu, Zhejiang, Jiangxi, Anhui, Guizhou, Sichuan, Yunnan. Grows on hillsides, in fields or under mixed woods, at an altitude of 700-3000 m.
Spiraea japonica L. f. var. glabra (Regel) Koidz.
Leaves ovate, ovate-oblong or long elliptic, apex acute or shortly acuminate, base cuneate to rounded, 3.5-9 cm long, margin sharply doubly serrate, glabrous on both sides. Compound corymb glabrous, up to 12 cm in diameter, flowers pink.
Produced in Anhui, Zhejiang, Sichuan, Yunnan. Grows in gravelly places or under forest and at forest edges, at an altitude of 1600-1900 m.
Spiraea japonica L. f. var. incisa Yu
Leaves ovate-oblong to oblong-lanceolate, apex shortly acuminate, base broadly cuneate to rounded, margin pinnately parted, with coarse sharp doubly serrate teeth, 6-9 cm long, short pubescent beneath. Compound corymb 5-7 cm in diameter, flowers pink.
Produced in Sichuan, Yunnan. Grows in alpine grassland shrub thickets, at an altitude of 3200-4000 m. The type specimen was collected from Weixi, Yunnan.
Spiraea japonica L. f. var. ovalifolia Franch.
Leaves smaller, broadly ovate or elliptic, apex rounded-obtuse or slightly acute, 2-4 cm long, margin rounded-obtuse doubly serrate, glabrous on both sides, glaucous beneath. Compound corymb 7-12 cm in diameter, flowers white.
Produced in Sichuan, Yunnan. Grows at forest edges on hillsides, on rocky slopes or in mountain gullies, at an altitude of 2500-3800 m. The type specimen was collected from Baoxing, Sichuan.
Spiraea japonica L. f. cv. Shibori.
White, pink and deep rose flowers bloom simultaneously on the same plant. The flowering period is long, lasting from early summer until frost. The flower color of cutting seedlings varies depending on the part of the plant from which the cuttings are taken.
Distribution area of Spiraea japonica
Spiraea japonica is native to Japan and the Korean Peninsula, and has been introduced and cultivated in East China.
Northern warm temperate deciduous broad-leaved forest region (main cities: Shenyang, Huludao, Dalian, Dandong, Anshan, Liaoyang, Jinzhou, Yingkou, Panjin, Beijing, Tianjin, Taiyuan, Linfen, Changzhi, Shijiazhuang, Qinhuangdao, Baoding, Tangshan, Handan, Xingtai, Chengde, Jinan, Dezhou, Yan'an, Baoji, Tianshui);
Southern warm zone deciduous broad-leaved forest region (main cities: Qingdao, Yantai, Rizhao, Weihai, Jining, Tai'an, Zibo, Weifang, Zaozhuang, Linyi, Laiwu, Dongying, Xintai, Tengzhou, Zhengzhou, Luoyang, Kaifeng, Xinxiang, Jiaozuo, Anyang, Xi'an, Xianyang, Xuzhou, Lianyungang, Yancheng, Huaibei, Bengbu, Hancheng, Tongchuan);
Northern subtropical deciduous and evergreen broad-leaved mixed forest region (main cities: Nanjing, Yangzhou, Zhenjiang, Nantong, Changzhou, Wuxi, Suzhou, Hefei, Wuhu, Anqing, Huainan, Xiangyang, Shiyan);
Middle subtropical evergreen and deciduous broad-leaved forest region (main cities: Wuhan, Shashi, Huangshi, Yichang, Nanchang, Jingdezhen, Jiujiang, Ji'an, Jinggangshan, Ganzhou, Shanghai, Changsha, Zhuzhou, Yueyang, Huaihua, Jishou, Changde, Xiangtan, Hengyang, Shaoyang, Guilin, Wenzhou, Jinhua, Ningbo, Chongqing, Chengdu, Dujiangyan, Mianyang, Neijiang, Leshan, Zigong, Panzhihua, Guiyang, Zunyi, Liupanshui, Anshun, Kunming, Dali).
Uses and purposes of Spiraea japonica: cut flowers, potted plants
Spiraea japonica has delicate and gorgeous flower color, abundant flowers, elegant leaves and unusual leaf shape, and is a good material for cut flower and potted plant production. Because of its strong resistance, very few pests and diseases, and relatively simple propagation technology, it is easy to achieve large-scale production, such as bouquets and flower baskets, and its flowering period is in spring and summer, so it can catch up with large festivals such as "June 1" Children's Day, and has considerable business opportunities. In the Hong Kong, China flower market, Spiraea plants have already been sold as cut flowers. It can be seen that developing woody cut flowers has great potential and broad prospects.
Colorful-leaf plants
In modern urban landscaping construction, colorful-leaf plants are receiving increasing attention. However, there are still relatively few types of colorful garden plants, and the color tones are also relatively monotonous. Spiraea 'Gold Princess' has purplish-red flowers, and both new leaves and branches and leaves at flowering are golden yellow. In addition, the leaves of Spiraea 'Honghua' turn dark red in autumn as the temperature drops. If planted in groups or rows in gardens, they can enrich the colors in the garden.
By using the dense and brilliant inflorescences and colorful leaf colors of Spiraea japonica, it can be combined with rocks, water bodies, fountains and sculptures, applying aesthetic principles such as unity and variation, rhythm and cadence, and contrast and harmony, to play a role in embellishment or setting off, forming garden landscapes of different styles.
Garden uses of Spiraea japonica
Spiraea japonica can be used for flower beds and flower borders, or planted on lawns and at corners of garden paths and other places to create beautiful summer scenes, and can also be used as foundation planting. Spiraea japonica has gorgeous flower color and is very eye-catching, and its flowering period coincides with late spring and early summer when few flowers bloom, so it should be vigorously promoted and applied. It can be arranged in patches on lawns, at path edges, in flower beds and flower paths, or planted in groups at a corner of a courtyard. It can also be used as a green hedge, and when in full bloom it looks like a brocade belt. For courtyard viewing, flower hedges, group planting and flower borders, it can be arranged on lawns and at corners of paths, or planted on both sides of gateways.
Foundation planting or groundcover material
In garden plant landscaping, Spiraea japonica has strong ecological adaptability and can be planted in groups on hillsides, roadsides, watersides, beside rocks and at lawn corners, and can also be planted around buildings as foundation planting to play a role in embellishment or beautification. For example, plant a single specimen or use it as an accent in an open lawn, or prune it into spherical or hemispherical shapes and use it as an accent in a small lawn, paired with brightly colored perennial flowers; the colorful hues can increase the charm of the lawn.
In landscaping in North China, there are many shade-tolerant tree species such as Amur honeysuckle and Sorbaria kirilowii. Spiraea japonica has strong shade tolerance and can also grow normally under forest. It is a shade-tolerant flowering shrub with relatively high ornamental value. In gardens it can be planted in groups, in rows, or used as groundcover material, etc., enriching the colors in the garden. It can be planted at forest edges, on the shady side of buildings, or mixed with other flowering trees and shrubs, such as Spiraea longigemmis, Spiraea goldflame and Spiraea trilobata.
Flower hedges and urban street greening
In urban landscaping, there are relatively few hedge plant materials. Spiraea japonica is a small shrub with fine leaves and abundant flowers, strong branching ability, robust growth and tolerance to pruning, making it an ideal hedge material. It can not only play a isolating role, but also has a long flowering period and brilliant flower color, and can form beautiful flower belts. Spiraea japonica can be paired with evergreen tree species; for example, 2-3 plants of Spiraea thunbergii pruned into geometric shapes can be dotted at equal distances between Chinese junipers, or it can be combined with other flowering shrubs to form a bright-colored pedestrian separation belt.
Flower beds and flower borders
Because the plant is short, it can be used directly in flower beds, achieving one-time planting and long-term benefit while reducing garden construction costs. In an open square, at the edge of a lawn adjacent to a road or on both sides of a road, it can be combined with other plants to form various patterns, and can also be planted on the outer edge of a pattern as an outline. In addition, it can also be used as a flower border to form beautiful flower belts. At the edge of a broad green lawn and trees, plant several clumps of Spiraea plants; when they bloom, they are a mass of flowers and quite attractive.
Flower language of Spiraea japonica
Flower language of Spiraea japonica: effort.
Spiraea japonica pictures
Cultivation techniques of Spiraea japonica Propagation methods of Spiraea japonica
Spiraea japonica has a long flowering period and gorgeous flower color, and its dense and brilliant inflorescences give an excellent ornamental effect. So how is Spiraea japonica cultivated? What are its propagation methods? Let's learn about them together next.
I. Cultivation methods of Spiraea japonica
1. Land preparation and bed making: deeply turn and loosen the soil. Generally, dig the nursery land 15-20era, level it carefully, compact it, and remove debris. When making beds, disinfect the soil. Set up reed curtain shade on the cutting bed. If conditions permit, add a layer of base fertilizer (farmyard manure) at the bottom of the bed, and at the same time mix in 1:5000 carbendazim for disinfection. Mix fertile loam and river sand at 1:1 as the upper layer of soil for the nursery bed, then water the seedlings thoroughly.
2. Cutting shoots and cuttings: collect current-year softwood. From mid-to-late June to early-to-mid July, use cuttings directly from clustered hardwood shoots growing from the rhizome and softwood cuttings growing from hardwood shoots. Cutting length is 10-12 cm, all without terminal buds, cuttings with 4-5 buds, shoot thickness 0.2em or more, retain 2-3 nodes of leaves at the upper end, cut to 8era long, keep the upper 2 leaves, and remove the lower 2-3 nodes of leaves and the upper flower spikes; the lower part inserted into the soil should have plump buds. After inserting, spray thoroughly with water so that the cuttings and substrate are closely combined.
3. Shading and plastic film covering: for open-field cuttings, build a shade shed; 75% shading is sufficient. If taking cuttings under forest, the trees in the forest can be used for shade. After the seedlings are inserted into the nursery bed, cover with plastic film and build it into an arch shape, with an arch height of 60em.
4. Transplanting: transplant in the following spring. Generally, in February-March, combine with transplanting; generally, in February-March, combine with transplanting, separate the suckers from the mother plant, prune appropriately and then plant separately. You can also fertilize the soil before division to encourage the mother plant to produce more suckers. When transplanting, first dig a hole, water, transplant with water, and cover with soil and tread firm. If propagating by cuttings in a greenhouse, cuttings can be taken at any time until autumn, and they can also be outplanted while cuttings are being taken; the following year they can be dug up and planted separately.
5. Maintenance management: to improve the survival rate of planting, keep a small section of roots when lifting seedlings, and by thinning branches and heading back, reduce water evaporation from the tree body and promote survival. After the seedlings are inserted, the film should be covered tightly, watered once a day, and sprayed with a fine-nozzle watering can; on cloudy days, water thoroughly once every 2 days. About 15 days after cutting, rooting basically begins. At this time, spray Tuzet once every 7 days, and spraying continuously 2 times is sufficient. Note that the humidity in the shed bed should be kept at 80%-90%, and the temperature below 28 °C. When it exceeds 28 °C, open the plastic film for ventilation and cooling.
II. Propagation methods of Spiraea japonica
Propagation by division, cuttings or sowing. After flowering, pruning should be carried out to remove the spent flowers.
1. Propagation by division: for division, generally in February-March, combine with transplanting, separate the suckers from the mother plant, prune appropriately and then plant separately. You can also fertilize the soil before division to encourage the mother plant to produce more suckers, then dig them up and plant separately the following year.
2. Propagation by cuttings: for cuttings, both softwood and hardwood can be used, and softwood is clearly better than hardwood.
3. Propagation by sowing: for sowing, after the seeds mature in autumn, pick them, dry them in the sun, thresh them and store them. The following spring, take the seeds out and sow them in pots. Because the seeds are very small, sowing propagation requires careful attention. Before sowing, first soak the potting soil thoroughly with water, then evenly scatter the seeds, cover with a layer of sifted fine soil, and afterward pay attention to moisture retention; seedlings emerge in about 1 month. Because sown seedlings are prone to damping-off, spray Bordeaux mixture before the disease occurs for control.
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