Propagation and Cultivation Techniques for Deutzia grandiflora and Methods for Pest and Disease Control

Deutzia grandiflora is a shrub with white petals that are oblong or obovate-oblong. It is a light-loving plant that tolerates slight shade, cold and drought. So how do you cultivate and propagate Deutzia grandiflora? Let's take a look below at the propagation and cultivation techniques for Deutzia grandiflora and methods for pest and disease control.

I. Propagation of Deutzia grandiflora

1. Propagation by seed

Harvest the seeds in autumn after they mature, dry them and remove the fruit husks, and remove debris to obtain clean seeds; after the seeds are sun-dried, store them in cold storage. Sow in the following spring; soak the seeds before sowing, with a sowing rate of 20-30 g per sq m. After sowing, cover with 1 cm of soil, and cover the bed surface with fine grass clippings or wood shavings, etc., to retain moisture and warmth and promote germination.

2. Propagation by cuttings

Softwood cuttings are generally used. In June-July, cut off slightly lignified young shoots and cut them into cuttings about 15 cm long, keeping 2-3 leaves on top, and insert them into a previously leveled seedbed, with a plant-to-row spacing of 10 cm x 20 cm. After cutting, immediately water thoroughly once, then cover with plastic film, and build a frame over the seedbed and cover it with a shade cloth. After cutting, water once a day to keep the seedbed moist. When the temperature is high at noon, the plastic film at both ends of the seedbed can be lifted at one corner to prevent the temperature inside the bed from getting too high.

3. Propagation by root division

Deutzia grandiflora can be propagated by digging up root suckers for transplanting. In order to obtain more and better suckers, increasing fertilizer and water management for the mother plant of Deutzia grandiflora that produces suckers can also achieve the expected results. The specific method is: along 50-100 cm from the mother plant of Deutzia grandiflora, dig a trench 30-40 cm deep, evenly apply 25 kg of decomposed farmyard organic fertilizer into the trench, and cover it with the original soil; the following year there will be many suckers for division and planting.

II. Cultivation of Deutzia grandiflora

1. Planting time

Transplanting can be done in spring or autumn, but in North China late autumn to early winter is better than spring and it readily survives; large seedlings can be transplanted with native soil. When planting, decomposed compost should be applied to each hole, and drainage should be paid attention to during the rainy season.

2. Planting method

The planting hole for Deutzia grandiflora is 60-80 cm in diameter and 45-50 cm deep. The bottom of the hole should be filled with a nitrogen-phosphorus-potassium compound fertilizer, then backfill with planting soil, firm the soil after covering, and water thoroughly once.

3. Water and fertilizer management

Deutzia grandiflora is relatively drought-tolerant and not tolerant of waterlogging, so it should not be watered too much. From spring bud break to the flowering period, it can be watered 2 times. In summer drought, it can be watered 2-3 times, and from autumn to before frost, it can be watered 1-2 times. Pay attention to drainage during the rainy season. In addition to applying 2-3 shovelfuls of decomposed compost per plant as a base fertilizer at planting, no further topdressing is needed afterward.

4. Shaping and pruning

After the flowers fade, the spent flowers should be pruned off; after leaf fall, cut off dead branches, overly dense branches and diseased branches. The small branches of Deutzia grandiflora have a relatively short lifespan, generally drying up in 1-2 years, so renewal pruning should be carried out every year in late autumn to early winter, that is, cutting off all the dried parts to encourage the lower dry branches to send out new shoots. When pruning, overly dense branches should also be cut off. After pruning, the plant will grow vigorously the next year and produce many flowers.

5. Pest and disease control

Deutzia grandiflora has relatively few pests and diseases, mainly aphid damage. When it occurs, spray one of the following on the leaves: 1.2% matrine-nicotine emulsifiable concentrate at 800-1000 times dilution, or 6% imidacloprid emulsifiable concentrate at 3000-4000 times dilution, or 5% acetamiprid emulsifiable concentrate at 5000-6000 times dilution.

The above are the cultivation and propagation techniques for Deutzia grandiflora. This beautiful and lovely flower is not only ornamental, but its fruit can also be used as medicine. It is a plant with great cultivation prospects.

Deutzia

Deutzia is a deciduous shrub of the genus Deutzia in the family Saxifragaceae. It loves light and tolerates slight shade. It likes a warm and humid climate, but is cold-tolerant. It is drought-tolerant and not strict about soil requirements, preferring soil rich in humus with a pH of 6-8. It is vigorous, has strong sprouting ability, and tolerates pruning. It is not strict about soil quality, but soil rich in organic matter and well-drained is preferable. The bark peels off in thin flakes. The small branches are hollow, reddish-brown, and have stellate hairs when young. The inflorescence is an upright panicle, 5 cm-12 cm long, with 5 petals, white or slightly flushed on the outside. In early summer the tree is covered with white flowers, clean and elegant, and its double-flowered variety is even more beautiful. It has long been cultivated in gardens at home and abroad. It is suitable for mass planting on lawns, roadsides, hillsides and forest edges, and can also be used as a flowering hedge and as planting material for rock gardens. The flowering branches can be used for vase display, and the roots, leaves and fruits can all be used medicinally.

Deutzia cultivation methods

Propagation by cuttings, sowing, layering or division is all possible.

Cuttings

It roots very easily; softwood cuttings taken in June and July root in half a month; hardwood cuttings can also be taken before bud break in spring, and the survival rate can reach 90% for both. Transplanting is best done during the leaf-fall period. After planting, dead branches should be pruned every winter or early spring. After the flowers fade, the spent inflorescences should be cut off promptly. For sowing, collect seeds from October to November, sun-dry and thresh them, then store them dry in sealed containers, and sow in the following spring.

Sowing

Broadcast sowing or drill sowing may be used, with a row spacing of 12-15 cm, and about 0.25 kg of seed per mu. Cover with soil just until the seeds are no longer visible, cover with grass after sowing, and uncover the grass and set up a shade frame after the seedlings emerge. The seedlings grow slowly; a 1-year-old seedling is about 20 cm tall and needs to be grown in the nursery for 3-4 years before it can be lifted and planted out. Deutzia can be managed extensively in gardens. Because the small branches have a relatively short lifespan, after several years the plant should be heavily pruned for renewal, which can promote vigorous growth and abundant flowering.

Pest and disease control of Deutzia:

Deutzia occasionally suffers from red spider mite and aphid damage; spray 1200-1500 times dilution of dichlorvos for control, or spray 1500 times dilution of 40% dimethoate.

Common varieties of Deutzia:

1) Double-flowered deutzia (cv. plena). The leaves have rounded blunt fine serrations. The flower buds are flushed red on the outside; the flowers are double, and after opening the petals are white, with the outer petals stained pale purplish-red on the outside.

2) Deutzia x magnifica, a hybrid, with a plant height of more than 2 m. The leaves are ovate-oblong or long-ovate. The flowers are double and pure white.

3) Deutzia parviflora Bunge: a shrub, 1-2 m tall. The bark is grayish-brown and splits off; the small branches are brown with scattered stellate hairs, and the old branches are gray and split into flakes. The buds are ovate-conical, with ridges, covered with brown scales and densely covered with stellate hairs. The leaves are opposite, with petioles 3-5 mm long; the leaf blades are ovate, narrowly ovate or obovate, 3.5-8 cm long and 2-5 cm wide, with a broad wedge-shaped or rounded base, an acuminate apex, and irregular small serrations along the margin, dark green on the surface with 5-6 radiating stellate hairs, the same color on the underside with scattered 8-12 stellate hairs, and simple hairs along the main vein. The inflorescence is corymbose, 2-5 cm in diameter; the pedicels and calyx are densely covered with stellate hairs; the calyx is bell-shaped with 5 calyx lobes, broadly ovate, shorter than the calyx tube; the petals are 5, white, rounded-obovate, 4-6 mm long, with stellate hairs; the stamens are 10, with short teeth on the upper part of the filaments; the ovary is inferior, with 3 styles, shorter than the stamens, persistent. The capsule is oblate, 2-3 mm long and 3-4 mm wide, mostly splitting into 3 valves, covered with stellate hairs on the outside. The seeds are numerous and small. The flowering period is June, and the fruiting period is August-September. It grows at the edges of broad-leaved forests or in thickets. It is distributed in Northeast and North China, and also in Russia and Korea. It is planted as a garden tree for ornamental purposes.

Image of Deutzia 4) Deutzia grandiflora: a deciduous shrub, 2 m tall. The leaves are ovate, 2.5-5 cm long, with an acute or short-acuminate apex, a rounded base, and small teeth along the margin. The flowers are white, 2.5-3 cm in diameter, in clusters of 1-3 in cymes. The flowering period is April, and the fruit ripening period is June. It grows wild in hillside thickets and is distributed in Liaoning, Inner Mongolia,

Hebei

, Shaanxi, Shandong, Hubei and other provinces.

5) Deutzia crenata 'Nikko': also known as small deutzia, native to Japan, now widely cultivated in various parts of East China. Its cultivar 'Snowball' (D. gracilis 'Nikko') was successfully bred in Japan in 1976. At that time it was named Deutzia Nakaiana 'Nikko', renamed Deutzia crenata var. Nakaiana 'Nikko' in 1980, and later taxonomists such as G. Meyer formally named it Deutzia gracilis 'Nikko'. This cultivar is famous for its low, full plant shape and abundant flowering. It is an excellent material for landscaping and beautification and one of the best horticultural varieties of deutzia. 'Snowball' is a small deciduous shrub, 30-60 cm tall, with a crown width of 60-150 cm; the branches are numerous and soft, and the plant shape is hemispherical. The simple leaves are opposite, lanceolate, 3-6 cm long, bright green, turning red in autumn. In the Shanghai area it blooms from April to May; the panicle is 10-15 cm long, and the full flowering period lasts 10-15 days; the small flowers are white and star-shaped, about 1.5 cm in diameter, and extremely numerous. At flowering time, the white flowers densely cover the entire hemispherical crown, hence the name Snowball.

6) Deutzia discolor Hemsl, also known as white-flowered deutzia. A shrub, 1-3 m tall; the small branches sparsely bear stellate hairs. The leaves are opposite, with short petioles; the leaf blades are ovate-oblong or lanceolate, 2.5-9.5 cm long and 1-3 cm wide, with a broad wedge-shaped or wedge-shaped base, an acuminate or acute apex, and small serrations along the margin; the upper surface sparsely bears stellate hairs (with 4-5 radiating lines), and the underside is white and densely covered with appressed stellate hairs (with 7-12 radiating lines). The inflorescence is corymbose; the calyx tube is densely covered with stellate hairs, 2.5-3 mm long, with 5 lanceolate lobes 3-5 mm long; the petals are 5, white, narrowly obovate, 0.9-1.2 cm long; the stamens are 10, and all filaments have 2 long teeth on the upper part; the ovary is inferior, with 3-4 styles. The capsule is nearly spherical, 5-6 mm in diameter. It is distributed in eastern Sichuan, Hubei, southern Shaanxi, southwestern Henan and Yunnan. It grows at the edges of mountain forests at an altitude of 1300-1900 m.

7) Deutzia amurensis (Saxifragaceae): a deciduous shrub, 1-1.3 m tall. The old branches are dark gray, and the small branches are brown with sparse stellate hairs. The leaves are opposite; the petioles are 4-8 mm long; the leaf blades are elliptical, 3-10 cm long and 2.5-6 cm wide, with an acuminate apex, a rounded or broad wedge-shaped base, and fine serrations along the margin; the upper surface is green with scattered stellate hairs, and the underside is lighter in color, with stellate hairs mostly having 5-7 radiating lines and no long central radiating line, and no simple hairs on the veins. The inflorescence is corymbose, borne at the ends of the branches, with many flowers; the pedicels and calyx are covered with stellate hairs; the calyx tube is about 2 mm long and has 5 broadly ovate lobes; the petals are 5, white, pointed-ovate; the stamens are 10, and the filaments have no teeth or have indistinct blunt teeth; the ovary is inferior, with 3 styles. The fruit is a capsule. The flowering period is July-August, and the fruiting period is August-September.

December Flower Propagation and Management Guide

Weather characteristics of December: This month, most parts of our country enter winter, and the weather turns colder. Snowfall increases from north to south in our country, and temperatures in the Jianghuai and Jiangnan regions successively drop below zero, with frequent heavy frost. This month, flower and tree care should focus on three aspects: first, doing a good job of heat preservation and freeze protection for cold-sensitive flowers and trees brought into greenhouses, plastic tunnels and homes; second, doing a good job of pruning, cleaning, and digging and fertilizing open-ground flowers and trees; third, doing the preparatory work of composting organic fertilizer and mixing potting soil.

I. Flower propagation

1. Sowing

Flower species that can be sown in greenhouses in December include: gloxinia, asparagus fern, clivia, tuberous begonia, cyclamen, winter coral, African daisy, etc.; flower and tree species that can be sown outdoors immediately after collection or stratified in sand for germination include: rose (such as 'Elizabeth'), nandina, Ardisia crenata, holly species, pyracantha, palm, privet, camphor tree, small-leaved privet, soapberry, photinia, Photinia davidsoniae, etc.

2. Cuttings

Woody ornamental flower and tree species that can be propagated by open-ground cuttings in December include: plum blossom (mainly cultivars such as 'Gongfen' and 'Lüe'); rose (mainly easy-to-root cultivars such as 'Elizabeth', floribunda rose and miniature rose); red-leaf plum, wintersweet (cutting with a heel), spiraea, boxwood species, etc. Among them, yellow subsoil is preferable for plum blossom and red-leaf plum cuttings, a mixed medium of rice-hull ash and fine sand at 2:1 is preferable for rose cuttings, and ordinary sandy loam can be used for other species, covered with plastic film to retain warmth and moisture.

In greenhouses, African violet can be propagated by leaf cuttings; combined with pruning, cuttings can be taken of hibiscus, geranium, epiphyllum, night-blooming cereus, jade plant, echeveria, portulacaria, kalanchoe, longevity flower, gold-leaved shrimp plant, shrimp plant, wax begonia, bamboo begonia, Rieger begonia, chloranthus, jasmine, clerodendrum, lantana, Schefflera, daphne, pothos, cordyline, etc. Using cold-frame seedbeds, cuttings can also be taken of gardenia, golden-heart (golden-edge) boxwood, mahonia, hypericum, forsythia, winter jasmine, podocarpus, false cypress, serissa, pyracantha, silver bud willow, Tripartita, etc. In addition, branches of trumpet creeper, lilac, grape, etc. can be cut and stored in sand for cuttings in the following spring.

3. Grafting

Excellent plum blossom cultivars, such as 'Guhong' and 'Zhusha', can be grafted in December using seedlings of apricot, fruiting plum and peach sown that year; after digging up the rootstock, use cleft grafting or cut grafting, then plant them in a seedbed at a certain plant-to-row spacing, burying soil up to above the graft union, even covering most of the scion; take care that water does not seep into the union, cover with plastic film to retain warmth and moisture, and remove the plastic film in the following spring after the scion buds sprout. Use dug-up wild rose plants to bud-graft excellent rose cultivars; or use strong branch sections (10-12 cm long) of the 'Elizabeth' rose cultivar, cut-graft or cleft-graft excellent rose cultivar scions onto the upper end, then insert the grafted 'Elizabeth' sections into a loose seedbed. The grafted parts can be buried together in sandy soil; take care that water does not seep into the graft union, cover with plastic film to retain warmth and moisture, remove the plastic film in the following spring after the scion sprouts, and only after it has completely survived may a blade be used to cut the binding tape at the union. In addition, red maple can be side-grafted indoors with bagging to retain moisture.

4. Layering

Flower and tree species that can be propagated by layering in December include: podocarpus, plum blossom, camellia, osmanthus, Michelia, Chaenomeles speciosa, purple magnolia, snowball, weigela, gardenia, winter jasmine, forsythia, hydrangea, Thunberg spirea, Viburnum macrocephalum, Spiraea thunbergii, pomegranate, etc.

5. Division

Herbaceous flower species that can be propagated by division in December include: zephyr lily, dwarf lilyturf, Reineckea carnea, hosta, purple hosta, red woodsorrel, Aspidistra, Cymbidium ensifolium, Cymbidium goeringii, Cymbidium faberi, sword fern, blackberry lily, iris, large-leaf lilyturf, Ophiopogon, Rohdea japonica, kalanchoe, Aglaonema. When cutting off the offsets from the base of a large variegated bromeliad, the small plants must already have grown on the mother plant for three to four months; otherwise the colored bands of the separated offsets easily disappear, which should be given special attention.

Woody ornamental plant species that can be propagated by division in December include: nandina, hypericum, mahonia, Chaenomeles speciosa, Rhapis, red-flowered spiraea, Caragana, forsythia, winter jasmine, jasmine, chloranthus, purple magnolia, gardenia, sisal, bamboo palm, Pleioblastus fortunei, etc.

II. Collecting seeds

The herbaceous flower seeds that can be collected in December are generally those of herbaceous flower species moved into greenhouses or cold frames, such as salvia species, globe amaranth species, marigold, French marigold, cyclamen, clivia, etc. Clivia seeds are best sown immediately after collection.

The main woody ornamental plants whose seeds can be collected in December include: rose, wisteria, privet, small-leaved privet, pyracantha, Ardisia crenata, holly species, camphor tree, photinia species. After treatment, these seeds basically all need to be stratified in sand for germination; only after the seeds crack and show white in the following year can they be sown in the ground. Under dry storage they easily lose viability, leading to failure in sowing and seedling raising the following year.

III. Transplanting and planting out

Herbaceous flower species that can be planted out in flower beds and flower borders in December include: dianthus species, ornamental kale, large-flowered pansy, snapdragon, calendula, daisy, etc. Some herbaceous flowers can also be potted and placed in plastic tunnels, such as daisy, calendula, snapdragon, ornamental kale, dianthus, pansy, etc., and can be used for street displays in the following spring.

In December, most deciduous greening trees and flowering shrubs can be transplanted and planted out, such as hibiscus, pomegranate, redbud, crabapple species, wintersweet, plum blossom, white magnolia, purple magnolia, soapberry, goldenrain tree, silk tree, horse chestnut, red-leaf plum, cherry blossom, papaya, Magnolia soulangeana, crape myrtle, wisteria, trumpet creeper, linden, tulip tree, red maple, ornamental peach, Sophora japonica, weeping pagoda tree, etc. For evergreen trees and flowering shrubs, transplanting should be more cautious. Evergreen tree species that can be transplanted in winter include: privet, osmanthus, palm, southern magnolia, camphor tree, azalea, holly, etc. When transplanting, first heavily reduce the main leader and large branches, and remove most of the leaves; at the same time, a large soil ball must be retained, the trunk bound with straw rope and wrapped with plastic film, and the cut ends of the trunk and large branches sealed with wax or wrapped in film to reduce water transpiration; after transplanting, water must also be sprayed frequently on the leaves and trunk to ensure normal survival.

Tree stumps and flowering plants that can be potted in December include: plum blossom, wintersweet stumps, camellia, sasanqua, Chaenomeles speciosa, Malus halliana. Placed in plastic tunnels for flower forcing, they can be expected to bloom during the Spring Festival.

In December, potted hyacinth, tulip, red-cupped narcissus, etc. should continue to be kept in tunnels for flower forcing, which can bring them into bloom around the Spring Festival.

1. Cold protection

In simple plastic tunnels where the temperature does not fall below 0°C, the following ornamental plants can be placed without suffering freeze damage, such as Asparagus densiflorus, asparagus fern, Aspidistra, Fatsia japonica, Aucuba japonica 'Variegata', Chinese fan palm, sword fern, Rhapis, nandina, Michelia, Ardisia crenata, pyracantha, camellia, Cymbidium goeringii, Cymbidium faberi, bamboo palm, Pleioblastus fortunei, cycad, etc.

For ornamental plant species requiring a wintering temperature not lower than 5°C, such as Norfolk Island pine, Schefflera, rubber tree, jasmine, Michelia alba, chloranthus, small coconut palm, calla lily, Philodendron, Monstera, Cymbidium ensifolium, Cymbidium sinense, Belgian azalea, bougainvillea, cyclamen, primrose, lantana, kumquat, bitter orange, lemon, areca palm, geranium, hibiscus, Buddha belly bamboo, etc., they can overwinter in double-layer plastic tunnels. For species requiring a wintering temperature not lower than 10°C, such as croton, Caladium, Peperomia, Maranta, lucky bamboo, fishtail palm, Brazilian iron, money tree, Fittonia, bromeliads, pink Dieffenbachia, poinsettia, large-flowered cymbidium, clerodendrum, gold-leaved shrimp plant, Aglaia, Phalaenopsis, Cattleya, Dendrobium, South American cycad, red (green) gem, Oncidium, Cymbidium hookerianum, etc., in double-layer tunnels with good sealing performance, appropriate heating must also be provided; during especially cold periods, from 4 p.m. to 9 a.m. the next day, straw curtains should be added on top of the tunnel and removed after the temperature turns warmer.

For the more cold-tolerant potted and bonsai plant species, such as wintersweet, plum blossom, crabapple species, rhododendron, pomegranate, Chinese elm, Japanese apricot, oak, crape myrtle, wisteria, boxwood species, podocarpus, trident maple, Chinese cypress, Chinese juniper, red cypress, Geum japonicum, holly, Fraxinus chinensis, etc., when the temperature is not lower than -10°C, they generally will not suffer freeze damage; in especially cold weather, plastic film or soft grass can be added for cold protection.

Whether placed in plastic tunnels, greenhouses, or indoors, bonsai, potted flowers, and foliage and fruit ornamental plants must, in addition to maintaining the corresponding indoor temperature, also be given ventilation; doors and windows can be opened around noon, when the temperature is highest in the day, for ventilation and air exchange, to prevent leaf drop, flower drop and fruit drop. When ventilating, care must also be taken not to let cold wind blow directly on the plants, so as to avoid adverse reactions.

2. Watering

For most potted flowers and bonsai placed in greenhouses, plastic tunnels and indoors, keeping the potting soil moist is sufficient; if the temperature is on the low side and too much water is given, it very easily causes root rot. When the temperature rises, the amount of watering can be increased and appropriate leaf spraying can be given.

For those potted flower species that bloom around the Spring Festival, such as camellia, sasanqua, Belgian azalea, plum blossom, wintersweet, cineraria, primrose, longevity flower, hyacinth, European narcissus, etc., and fruit ornamental species such as bitter orange, lemon, bergamot, four-season tangerine, kumquat, winter coral, Ardisia crenata, nandina, etc., not only must the potting soil be kept moist, but leaf spraying must also be given to promote the swelling of flower buds and to increase the vividness of the flowers and fruits.

For most foliage plants placed indoors, the potting soil must be kept moist and leaf spraying must also be given, always keeping the leaf surface clean; for less cold-tolerant foliage plant species, such as pink Dieffenbachia, Syngonium, Maranta, croton, Aglaonema, etc., when the room temperature is already close to the lowest temperature limit they can tolerate, special attention should be paid to controlling the amount of watering to ensure they can overwinter safely.

The watering time in December is best set in the 3-4 hours around noon, and the water temperature should be kept basically consistent with the air temperature and soil temperature, to avoid adverse reactions in potted flowers caused by water temperature being too low.

For newly transplanted flowers and trees outdoors, inspections should be made frequently and supplementary watering given in time; for transplanted evergreen trees, appropriate leaf spraying can be given around noon to prevent the leaves from drying, shrinking and falling off.

3. Fertilizing

For most potted flowers and trees, foliage plants and bonsai placed in ordinary plastic tunnels, fertilizing should be stopped; otherwise it very easily causes root rot and death of the plants.

For most greening trees and flowering plants grown in the ground, such as crabapple species, southern magnolia, white magnolia, purple magnolia, Manglietia, Michelia species, red maple, gardenia, horse chestnut, camphor tree, osmanthus, wintersweet, plum blossom, cherry blossom, red-leaf plum, soapberry, silk tree, goldenrain tree, palm, peony, tree peony, forsythia, hypericum, grape, rose, spiraea, tulip tree, mock orange, deutzia, pomegranate, crape myrtle, wisteria, pyracantha, nandina, lilac, trumpet creeper, Banksia rose, hypericum, weeping willow, Japanese cedar, deodar cedar, cypress species, Sophora japonica 'Pendula', flowering almond, dwarf flowering cherry, white silk plum, photinia, redbud, hibiscus, etc., in December, while digging and turning the garden soil, fertilizer can be buried and applied around the outer perimeter of the plant root system, such as cake fertilizer, pig and cattle manure, pond mud, septic tank residue, etc., to lay a good material foundation for next year's growth and flowering.

For potted flower species placed indoors at 10°C to 15°C, such as camellia, sasanqua, azalea, plum blossom, wintersweet, gold-leaved shrimp plant, shrimp plant, bromeliads, daphne, cineraria, primrose, cyclamen, Chaenomeles speciosa, hyacinth, clivia, tulip, freesia, etc., topdressing with 1.2% monopotassium phosphate solution can continue, to promote flower bud formation and flowering of the plants.

4. Pruning

Prune hedges, green walls and ball-shaped topiary that were not pruned in November; hedge and green wall types such as privet, small-leaved privet, Ligustrum sinense, large-leaved boxwood, Sabina chinensis, four-season osmanthus, Photinia davidsoniae, etc.; ball types such as holly, bayberry, photinia, boxwood species, Pittosporum, forsythia, pyracantha, dragon juniper, Sabina chinensis, etc. While completing pruning, fertilizer can be applied.

For ground-planted flowers and trees not yet pruned in November, such as rose, crape myrtle, palm, red-leaf plum, photinia, plane tree, plum blossom, wintersweet, etc., carry out shaping and pruning; after pruning is finished, fertilizer can be buried and applied around the root system.

For bonsai plant species that are mainly pruned, such as Chinese elm, Japanese apricot, holly, Fujian tea, trident maple, oak, Fraxinus chinensis, pyracantha, serissa, podocarpus, Chinese cypress, Chinese juniper, crabapple, papaya, etc., continue pruning in December to lay a good framework for next year's growth; for plants that have not been repotted for many years, repotting can be combined with pruning.

5. Pest and disease control

For flowers and trees whose leaves are prone to pests and diseases, such as grape, crabapple species, rose, China rose, camellia, crape myrtle, etc., collect the dead branches and fallen leaves under the plants and burn them, which can reduce the occurrence of diseases next year. At the same time, spray lime sulfur mixture for sterilization and disinfection.

For powdery mildew on potted cineraria and gray mold on primrose, the former should be controlled promptly with triadimefon or thiophanate-methyl, and the latter with thiophanate-methyl.

For flower and tree species in greenhouses and plastic tunnels that are prone to scale insects, such as bitter orange, bergamot, cycad, camellia, Aspidistra, etc., first wipe them once with a cloth, then control them with pesticides such as methidathion.

For flower and tree species on which aphids often appear on potted plants when ventilation is poor, such as Michelia alba, Aglaia, bitter orange, China rose, Fujian tea, etc., tobacco water can be used for control.

On the trunks and large branches of open-ground flowers and trees such as Pittosporum, osmanthus, plane tree, camellia, small-leaved privet, pyracantha, oleander, crabapple, white magnolia, redbud, gardenia, deodar cedar, photinia, crape myrtle, wintersweet, etc., various scale insects often appear, such as Ceroplastes ceriferus, Ceroplastes japonicus, red wax scale, armored scale, arrowhead scale, mealybug, felt scale, etc.; at this time, use higher concentrations of pesticides such as methidathion, quinalphos and buprofezin for spraying and killing, and pesticide damage is rarely caused.

6. Composting fertilizer

For the need of raising seedlings and mixing potting soil next year, the idle winter time can be used to pour rapeseed cake, soybean cake, tea seed cake, etc. into water vats or water tanks, add water, and seal them for soaking, retting and fermentation.

Stack dry dead grass, fallen leaves, shrubs, branches, etc. in layers with garden soil, set fire and burn them to form burned soil, which is an excellent covering soil for sowing and raising seedlings next year.

Mix stable manure, pond mud, chicken droppings and pigeon manure, etc. with garden soil for composting, seal and ferment, and it can be used for topdressing seedlings and mixing potting soil in the coming year.

7. Mixing potting soil

Using the idle winter time, find a piece of open ground or a spot under the shade of trees, and pile up as much potting soil as possible to prepare for repotting and potting herbaceous flowers in the coming spring. Generally, use 4 parts garden soil, 2 parts leaf mold (or 2 parts alpine humus soil), 1 part fine sand, 1 part each of composted sawdust, tobacco powder or rice-hull ash, plus about 5% composted cake fertilizer and 2% to 3% compound fertilizer. The garden soil and leaf mold should be sieved to remove stones, tree roots and other debris, and after being fully mixed, cover with plastic film; it can also be piled indoors, and after 3 to 4 months it can be used for repotting or potting herbaceous flowers.

8. Digging and freezing the soil

For garden plots to be used next year for sowing, cuttings and planting out seedlings, plowing can be carried out in December; for garden plots for sowing and planting out seedlings, cake fertilizer, stable manure, pond mud, etc. can be applied before turning the soil; do not make beds for the time being. After overwintering and freezing, furrows can be drawn and beds made in the following early spring, which can greatly reduce the cost of seedling management and also reduce the occurrence of pests and diseases.

Bonsai care knowledge

Ornamental plant species suitable for bonsai shaping in December include: podocarpus, false cypress, Chinese juniper, Chinese cypress, Sabina chinensis 'Pyramidalis', oriental arborvitae, creeping juniper, Shimpaku juniper, black pine, five-needle pine, red pine, Geum japonicum, holly, holly, Euonymus, ginkgo, serissa, Caragana, Chinese elm, Japanese apricot, trident maple, wintersweet, tamarisk, Chaenomeles speciosa, Malus halliana, Chaenomeles cathayensis, boxwood, pearl boxwood, wisteria, crape myrtle, banyan, Fujian tea, Fraxinus chinensis, oak, etc.

For bonsai plants that have been fixed and shaped with palm fiber (rope) or metal wire, if the fixation has already lasted one year, or if obvious constriction marks are found on the trunk or branches, the original binding material should be untied and metal wire or palm rope should be used again for hanging, tying and pulling.

For ground-planted shaped plum stumps, podocarpus, crabapple, ginkgo, Chinese juniper, crape myrtle, etc., after carrying out some necessary pruning and shaping, select suitable pots and plant them well, and strengthen management, so that they can be used for display in public places or rooms in the coming year.

In winter, for some shallow-pot landscape bonsai and tree-stump bonsai, careful management is a must: first, prevent the potting soil from freezing and damaging the plant root system; second, prevent freezing from disintegrating the artificially cemented rocks; third, prevent the plants planted on the rockery from freezing to death or drying to death. They can be placed in a place that does not freeze, and watered and sprayed regularly, so that they can overwinter safely.