1. Land

The soil in which bonsai plants grow is generally artificially prepared. Although it is loose, fertile and rich in nutrients, the soil volume is small and the total nutrient capacity is small. It is necessary to supplement the nutrients needed for plant growth and development by turning over pots and changing soil.

2. Temperature

Because the flowerpot is exposed to the air, the temperature change of potted plants is obviously different from that of ground plants. According to the determination of Hebei Agricultural University, the diurnal variation of soil temperature of potted fruit trees is basically consistent with the diurnal variation trend of temperature. Compared with the soil temperature in orchard, the soil temperature of potted fruit trees becomes larger day and night, and the temperature stability is poor, which is very unfavorable for root growth. The roots are easily burned by high temperature in summer and damaged by low temperature in winter. Therefore, attention should be paid to pot soil for shade in summer and cold protection in winter.

Step 3: Moisture

Because potted plants are often placed in the open air, the evaporation of water in the basin is large, while the soil in the basin is limited and the water capacity is small, so the water loss can not be supplemented by the deep soil moisture. So potted plants are more prone to drought than ground plants. It was observed that the soil water content of potted Yali pear in 0-5cm decreased by 7% within 24 hours, while the soil in pear orchard decreased by only 65,438 0.53%, the former was 4.6 times that of the latter. Because the basin soil is easy to lose water, it must be replenished in time by watering.

lamplight

The crown of bonsai plants is very small, and the light in the crown is uniform and easy to move. Therefore, the lighting conditions of bonsai plants are generally better than those of ground plants. However, when displayed indoors, sometimes it can't meet the lighting requirements of some light-loving plants, which leads to poor growth and development of plants. For example, the bonsai of fruit trees in the north will lose their fruits and leaves for a long time in poor indoor light. At this time, bonsai should be regularly moved outdoors for light conservation, and the exchange interval between indoor and outdoor is about 7 days.

(B) the growth and development characteristics of bonsai plants

1. Root growth characteristics

The root system of bonsai plants generally consists of fibrous roots without obvious taproots, which is mainly due to the fact that the taproots are cut off when potted plants are put into the pot, and the extended growth of the root system is restricted by the wall of the pot, thus producing a large number of fine roots. The root growth and distribution of bonsai plants under the constraint of pots and pans have also changed greatly compared with the ground planting conditions. For example, in the early stage of root growth of potted fruit trees, most of them grow downward and outward along the basin edge, and the amount of roots at the basin bottom increases obviously, gradually forming root mats. This is due to the centrifugal growth habit of roots and the superior ventilation conditions of basin soil near the basin wall. During this period (about 1-3 years after planting), compared with the ground planting conditions, the root length was not significantly shortened, but the root system mostly circled around the basin bottom. With the growth of tree age (2-3 years later) and the increase of the number of roots, the roots are intertwined to form a dense root mass, which fills the whole basin. At this time, the limited potted soil can no longer accommodate the continuous growth of root volume, and the root mass begins to age, which directly affects the functions of root absorption, synthesis and transportation. At this time, it is necessary to change the culture soil and prune and update the root system by turning over the pot. Therefore, the cycle of root growth, senescence and regeneration of potted plants is obviously shorter than that of in-situ plants. Because the root distribution of bonsai plants is limited by pots and pans, it can't be as deep and wide as when planted in the ground, so its root system is sensitive to the changes of external environmental conditions and its stress resistance is reduced.

2. The growth of branches and leaves Because of the limitation of pots and pans, the root growth of bonsai plants is inhibited, which reduces the supply of nutrients and water to the aboveground parts, thus inhibiting the growth of branches and leaves, making the plants look short and compact, and the leaves become smaller.

When modeling bonsai plants, pruning and binding will inhibit the growth of bonsai plants Pruning will reduce the total leaf area and the production of photosynthetic products, thus reducing the total growth of the whole plant, while the bending of branches caused by binding will slow down the transpiration rate, increase the content of hexene in branches and inhibit the growth of new shoots.

3. Flowering characteristics

Because the growth of bonsai plants on the ground is inhibited, which is beneficial to nutrient accumulation and flower bud differentiation, the initial flowering period of bonsai plants is generally 1-3 years earlier than that of ground planting.

Second, the root management of bonsai plants

The root management of bonsai plants is to create good conditions for the growth and development of roots, which mainly includes soil, fertilizer and water.

(1) Pot soil preparation and disinfection

1. Pot soil preparation

Potted soil is the material basis for the growth and development of bonsai plants. It can supply water, nutrients and air needed by plants, and play a role in fixing plants. Most bonsai plants are limited by pots, and the soil is thin and small. At this time, higher requirements are put forward for the quality of potted soil, and good potted soil is the premise to ensure the normal growth and development of bonsai plants. Generally speaking, a good potted soil should have the following conditions: loose soil, rich humus, rich and comprehensive nutrients, good drainage and air permeability, strong water and fertility conservation, suitable plant pH and no pests and diseases.

Potted soil is often made of some materials, mainly garden soil, humus soil, compost soil, pond mud, peat, yellow sand and so on. Because of the different sources and habits of materials in different places, the formula of basin soil used is also different. The general formula of potted soil is: garden soil+humus soil+yellow sand+bone meal, the volume ratio is 6:8:6: 1, or peat+yellow sand+bone meal, the volume ratio is 12:8: 1. Generally, flowers and trees are compost soil+garden soil with a volume ratio of 1: 1, chrysanthemums are compost soil+garden soil+plant ash+fine sand with a volume ratio of 2:2: 1: 1, and azaleas can be added with a small amount of yellow sand.

2. Potted soil disinfection

Pot soil materials often contain germs and eggs harmful to plants, so pot soil must be disinfected before use. There are two main methods for disinfection of basin soil: steam disinfection and chemical disinfection.

(1) steam disinfection: introduce the steam in the boiler into a closed container filled with potted soil with steel pipes or hoses, and sterilize it with steam at 100-200℃ 1 hour. A small amount of pot soil can also be disinfected by pressure cooker 15-20 minutes.

(2) Formalin (40% formaldehyde) is commonly used for chemical disinfection. Every cubic meter of soil is evenly stirred with 400-500ml formalin solution, covered with plastic film, sealed for 2-4 hours, then spread out and ventilated for 3-4 days, and can be used after formalin volatilizes.

(2) basin loading and basin turning

1. gaoku

The process of planting plants in flowerpots for the first time is called potted plants. When filling the basin, first place broken basin bricks or screens at the drainage holes at the bottom of the basin to prevent the leakage of basin soil and facilitate drainage. Screen windows should be used for shallow pots, broken tiles can be used for deep pots, and multiple broken tiles should be used to empty the lower layer of pots for deeper pots. When planting a big tree in a shallow pot, tie the tree firmly to the bottom of the pot. Before blocking the drainage hole at the bottom of the basin, an iron bar can be placed at the bottom of the basin, so that the metal wire can pass through the hole at the bottom of the basin, and the iron bar can be tied to fix the metal wire, and then the other end of the metal wire can be tied to the roots to fix the trees.

When planting, a small amount of nutrient soil is added to the bottom of the basin, the root system of the plant is spread on the soil and fixed in a proper position, then the remaining nutrient soil is added, and the soil and the root are bonded with bamboo sticks while adding the soil. When adding soil to the mouth of the basin, you can leave some sprinklers for watering. If it is a shallow basin, there is no nozzle left, and sometimes it is necessary to pile up soil for planting. The depth of plant planting should also be based on the needs of modeling. Generally, the roots will slightly protrude from the ground.

Water immediately after planting, preferably with a watering can. Water it fully for the first time, then put it in a windless and semi-cool place and pay attention to spraying water every day. Generally, new roots can be born after half a month and transferred to normal management.

Turnover washbasin

The process of replanting potted plants in pots with updated soil is called turning pots.

(1) The purpose of turning over the pot

(1) renew the basin soil to promote plant growth. After a certain number of years, the roots of bonsai plants are densely covered with the whole flowerpot, forming an aging root mass. At the same time, the nutrients in the basin soil are exhausted and the soil is hardened. At this time, it is necessary to renew the pot soil by turning over the pot to promote the growth of roots, so as to ensure the nutrient supply of plants and avoid the weak growth and death of plants. In the process of bonsai seedlings growing year by year, when the original pot is too small to affect the ground growth, it is necessary to turn over the pot to replace the larger pot and add new soil to expand the nutrient area of the root system. In addition, when plant root diseases and insect pests occur, it is also necessary to turn over the pots to control the damage.

② Improving the ornamental value of bonsai When bonsai is used for display and exhibition, the original pottery pots must be replaced with high-grade pots such as purple sand pots and pottery pots to improve the ornamental value. In addition, according to the needs of modeling, sometimes it is necessary to change the deep basin into a shallow basin, or change the position or posture of plant planting, and then the basin needs to be turned over.

(2) years of river basin turnover

The pot turning period should be determined according to tree species, tree age, bonsai specifications and growth conditions.

① Tree species: bonsai of flowers and fruits, which consumes a lot of nutrients, and it is best to turn over the pots once a year. Pine and cypress grow slowly and need less fertilizer, so it can be turned over once every 3-4 years. Generally, broad-leaved trees can turn over pots once every two years.

② Tree age: Young trees grow fast, turning once every 65,438+0-2 years, mature trees every 2-3 years and old trees every 3-5 years.

③ Specifications: Small bonsai is small in size, once every 1-2 years, once every 2-3 years for medium bonsai, and once every 3-5 years for large bonsai.

④ Growth status: Generally speaking, when the root system has covered the whole basin, and there are roots protruding from the drainage hole or growing upward from the edge, it is necessary to turn over the basin.

(3) Turning time

Generally, it is advisable to turn over pots before germination in spring, but the climate in different regions is different, so we should adjust measures to local conditions and master them flexibly. Different plant species have different suitable pot-turning periods. For example, after flowering, plum blossoms should be combined with pruning and turned over at the same time, preferably in May or September. If turning the pot only changes the small pot into a big pot without breaking the ground, it can be done all year round.

(4) the pot-turning method

(1) generally don't turn the pot over and then water it, so that the soil in the pot is slightly dry. First, remove some soil around the basin, turn the basin upside down, pat the bottom of the pot with your hands, or tap the edge of the basin gently, so that plants can come out of the basin with roots and land. For grafted stumps, be careful when removing pots to avoid the scion from the rootstock.

② After soil removal and root cutting, the topsoil, surrounding soil and subsoil shall be removed with bamboo sticks, and the amount of soil removal is generally 1/3- 1/2 of the original basin soil. While covering the soil, we should trim the root system, cut off dead roots, rotten roots, diseased roots and over-dense roots, and cut off long roots.

③ When planting, you can choose a suitable new pot, or you can still use the original pot. The molded stump bonsai should be planted in the original pot, not in the big pot, so as to control its growth and maintain its original tree shape. Plants can be planted in their original positions or adjusted appropriately. If you make a bonsai, you should put more subsoil in the pot to expose the root of the pot. Other planting technical requirements are the same as potted plants.

(3) Water

Watering is one of the main management work of plant bonsai. Because the pot soil is easy to lose water and dry, it should be watered in time to replenish the water in the pot soil to ensure the normal growth and development of bonsai plants.

1. Water principle

The principle of "no watering, no watering, no watering" should be mastered in watering bonsai plants. "No watering" means that potted soil is watered only when it is dry. If the potted soil is watered too frequently and too wet for a long time, it will lead to hypoxia and root suffocation and death. The sign of dry basin soil is generally that the basin soil is white and hard, or the sound of knocking on the basin edge with a wooden stick is crisp.

"Water pouring through" means that water must be soaked through the whole basin soil every time, marked by water flowing out of the holes at the bottom of the basin. If the water can't be poured thoroughly, only half of the water or ground water will be poured, which will cause the root system in the lower part of the basin to die because of dryness, and will also cause salt accumulation in the basin soil, causing saline-alkali harm.

Step 2 water the foundation

The time and frequency of watering should depend on the bonsai plant species, plant growth and development stage, season and weather conditions.

(1) Plant species

Plants that like humidity, such as bamboo and azalea, should be watered more to make the soil moist, while pine trees and cycads should be watered less to make the soil dry.

(2) Plant growth and development stages and seasons

In early spring, plants are not fully germinated, the temperature is low, and the water demand is low. Water can be watered once every 1-2 days, around noon. In spring and summer, the temperature is high, the evaporation is large, and the plants are in the peak season, so the water demand is large. Therefore, it is necessary to water 1-2 times a day, preferably once in the morning and evening, and once every 1-2 days when the plants grow slowly in autumn.

(3) Weather conditions

When the weather is dry and there is little rain, you should water more. In the rainy season in the south, it is necessary to water less or not. In case of continuous rainfall, the accumulated water in the basin should be eliminated in time or the basin should be put down.

3. Watering technology

(1) water quality requirements

It is best to use unpolluted river, lake and pond sugar water for irrigation. Well water and tap water must be put into the water storage tank in advance, and dried for 1-2 days to raise their temperature, and the chlorine in tap water can be volatilized before use.

(2) Watering method

(1) The root watering method is to directly pour water into the root soil, which is the most common watering method. When watering, in addition to washing the roots with water, under normal circumstances, the water nozzle should not be too high from the basin surface to avoid washing away the soil and moss. The root pouring method should pay attention to not pouring, but pouring thoroughly.

(2) foliar spraying, that is, watering the whole plant with a fine-hole watering can. In order to make up for the lack of root water absorption, the plants that have just entered the pot or changed pots should be sprayed with clean water 1-2 times a day, which can improve the survival rate and speed up rejuvenation. Evergreen deciduous trees or conifers should be sprayed with more water to make them flourish. Deciduous trees should not spray more leaf water to prevent branches from growing white, destroying trees and inhibiting flower bud formation.

(3) Submerged miniature bonsai and shallow potted plant bonsai with soil protruding from the basin surface are commonly used in this method. First, put the bonsai into a large empty pot, and then add water to the lower edge of the pot mouth of the bonsai, so that the water can penetrate into the pot soil from the drainage hole at the bottom of the bonsai, and it will be saturated when the surface of the pot soil changes from dry to wet.

No matter which method, when watering, we should pay attention to avoid blooming flowers, prevent the water in the flowers from causing flowers to rot, and also pay attention to keeping the drainage holes at the bottom of the basin unobstructed to prevent the water at the bottom of the basin from causing rotten roots.

(4) Fertilization

1. Types of fertilizers

(1) organic fertilizer. It mainly includes human excrement, manure, poultry excrement, green manure, bone meal, plant ash, bean cake, sesame sauce residue, etc. And the waste organic matter such as fishy smell water and rice washing water in daily life. Organic fertilizer is the main fertilizer for bonsai plants because of its wide source, low cost and comprehensive nutrients. Organic fertilizer must be fermented and decomposed before application, otherwise it will release heat and burn plant roots after fertilization.

(2) Inorganic fertilizer. Mainly refers to synthetic fertilizers. Commonly used are urea, ammonium sulfate, potassium dihydrogen phosphate, calcium superphosphate, ferrous sulfate and so on. The application of chemical fertilizer is relatively clean and hygienic, and the bonsai placed indoors should be mainly topdressing with chemical fertilizer. Fertilizers contain specific nutrients. When plants are in urgent need of certain nutrients or lack of elements, the effect of applying corresponding fertilizers is better than that of applying organic fertilizers.

2. Fertilization method

(1) base fertilizer. The fertilizer applied to the soil of the basin when the basin is put or turned over is called base fertilizer. Fertilizers used as base fertilizers are generally decomposed solid organic fertilizers, such as compost soil, bone meal and decomposed cake fertilizer. When applied, they can be used as components of potted soil and mixed into potted soil. The effect of base fertilizer is slow, but it takes a long time and can supply plant nutrients for a long time.

(2) topdressing. Topdressing is to supplement the lack of nutrients in the basin soil during the plant growth period, which is called topdressing. Topdressing can be divided into soil topdressing and root topdressing.

① Topdressing of soil. Usually, the decomposed organic fertilizer solution is diluted with water and applied to a pot. The principle of topdressing organic fertilizer solution should be "thin fertilizer and diligent application", and the fertilizer solution is generally diluted 15-20 times. Chemical fertilizer should be used for topdressing indoor bonsai.

② Topdressing outside the roots. That is to say, foliar spraying of chemical fertilizer solution has the advantages of fast fertilizer efficiency and low fertilizer consumption. Spraying 0.2% potassium dihydrogen phosphate before flowering can promote flowering and improve fruit setting rate. When plants have element deficiency, they can also be treated by topdressing outside the roots. It is advisable to spray topdressing before 10 am and after 4 pm, and strictly control the fertilizer concentration to avoid fertilizer damage.

3. The relationship between fertilization and plant species and plant growth and development stages.

Generally, foliage plants mainly apply nitrogen fertilizer, and the amount of fertilizer applied is based on the principle of not stimulating growth. Flower and fruit bonsai needs more fertilizer, and it is appropriate to apply more phosphate fertilizer. Plants that like acidic soil should apply "alum fertilizer water" appropriately. "Alum fertilizer water" is used after adding about 1% ferrous sulfate to organic liquid fertilizer and fermenting and decomposing it.

Different stages of plant growth and development need different nutrients. Generally, in late spring and early summer, plants enter a vigorous growth period and should be fertilized more. After autumn, the growth rate slows down, so apply less chemical fertilizer to avoid its inflated growth. In winter, most plants enter dormancy period, so fertilization should be stopped. Phosphate fertilizer should be applied to flower and fruit bonsai during flower bud differentiation and before and after flowering.

Three, bonsai plants tree management

The purpose of plant and tree management is to maintain and improve the artistic modeling and landscape effect of bonsai plants, control pests and diseases, and ensure the healthy growth of bonsai plants.

(a) shape and modification

Once the bonsai plants are cultivated and shaped, they should try their best to maintain the existing artistic shape in the future maintenance work. Generally, there can be no major changes, only minor adjustments. In daily management, pruning measures such as bud wiping, drying and coring are mainly adopted to control the growth of branches so as not to destroy the existing artistic modeling. This is the problem of maintaining the shape of bonsai plants. In some cases, under the influence of disasters such as wind disasters, pests and diseases, bonsai plants may have big branches broken or withered. In this case, it is impossible to keep the shape, so it is time to cultivate new trees again. This is the problem of modification.

Bonsai plants are constantly growing and changing, and it is impossible to make the tree absolutely unchanged. So conformal can only be relative. The process of shape-preserving is to constantly adjust the changing branches, so that the tree does not change as a whole, but the changes in details are inevitable. This constant adjustment of the shape of branches is not mechanical, but the re-creation process of bonsai artistic modeling, which is precisely the continuation of bonsai artistic creation.

The maintenance and decoration measures of bonsai are still inseparable from pruning and binding technology. For details, please refer to the third section of Chapter III, which will not be repeated here.

(B) to promote flower bud differentiation

Flowers and trees bonsai and fruit tree bonsai must have flowers and fruits to have the best ornamental effect, and the premise of flowering and fruiting is the formation of flower buds. Therefore, in the maintenance and management of bonsai of flowers and trees, besides shape preservation or decoration, attention should be paid to promoting the formation of flower buds.

It is generally believed that the accumulation of carbohydrates and other nutrients in plants is a prerequisite for the formation of flower buds. Therefore, all measures conducive to increasing the accumulation of nutrients in plants can promote the differentiation of flower buds. These measures mainly include:

1. Strengthening the supply of fertilizer and water and promoting the robust growth of branches can increase the production of photosynthetic products.

2. Take measures such as removing the core, twisting the tip and taking branches to control the flourishing leaves and reduce the consumption of nutrients.

3. After flowering, the fruits without ornamental value should be removed to save nutrition.

4. By girdling, girdling and other measures, vigorous growth of trees and branches can be suppressed, and nutrient accumulation can be increased.

5. It is also an effective measure to increase the application of phosphorus and potassium fertilizer during flower bud differentiation.

(3) ensure fruit setting

Some varieties in bonsai of fruit trees have low fruit setting rate, so measures must be taken to ensure fruit setting rate. The common measure to protect fruit is artificial pollination. It should be noted that many fruit tree varieties must be cross-pollinated to bear fruit. Spraying gibberellin at flowering stage can also improve the fruit setting rate of some tree species.

(4) Pest control

Bonsai plants grow in limited pot soil, their growth is inhibited, and their ability to resist pests and diseases is generally lower than that of ground plants. Once pests and diseases occur, they are very harmful. Therefore, the policy of "prevention first" should be adopted to avoid the occurrence of bonsai plant diseases and insect pests. When diseases and insect pests occur, they should be cured in accordance with the principle of "early treatment, small treatment and treatment" to prevent their spread. Preventive measures for bonsai diseases and insect pests mainly include:

1. Use decomposed fertilizer to disinfect the soil.

2. Strengthen the daily management of bonsai. Scientifically fertilize, water and prune the site, keep the site clean and free of weeds, maintain proper temperature and humidity, and have good ventilation and light.

3. Spraying 1% bordeaux mixture 1-3 times on bonsai plants in spring can prevent various fungal and bacterial diseases.

4. Strengthen plant quarantine. Eliminate the source of infection. Newly introduced bonsai plants at home and abroad must be strictly inspected according to the quarantine objects stipulated by the state to prevent the quarantine objects from entering the local area. Newly excavated or purchased stumps should be carefully inspected for pests and diseases. If there are pests and diseases, preventive measures should be taken in time. When individual bonsai plants have diseases and pests, they should be isolated in time to prevent the spread.

Fourth, environmental management.

Light, temperature and air are environmental factors that directly affect the growth and development of bonsai plants. Environmental management is also one of the important contents of bonsai conservation management.

(A), lighting environment management

The influence of light on bonsai plants mainly has two aspects: one is the intensity of light, and the other is the length of illumination time.

1. Light intensity According to the requirements for light intensity, bonsai plants can be roughly divided into three categories:

(1) Sun plants are called photophobes. This kind of plant can grow normally in full light and is not tolerant of shading. For example, five needles pine, black pine, whole money pine, peach, plum, grape, apple, ginkgo, pomegranate, begonia flower, Caragana, tamarisk, Phyllanthus urinaria, true cypress, pyracantha, Lagerstroemia indica and rose are all positive plants. Generally, the photosynthetic efficiency of sun plants is the highest under full illumination, and its light compensation point is also high, with an average of 30%-50% of full illumination.

(2) Negative plants or shade-loving plants. Most of these plants grow on mountain backs, gullies, shady slopes of streams, under forests or forest margins, and can only grow normally in the shade. Like diffuse light, can't stand strong direct light. The light compensation point is low, and the average does not exceed 10% of the total illumination. Such as fern, asparagus, Hosta, Orchidaceae, azalea, camellia and so on.

(3) Shade-tolerant plants have extensive adaptability to light. Although they are suitable to grow in full light, they are plastic in morphology and ecology, and the minimum illumination required can reach110-115 in full light. Such as Chimonanthus praecox, Flos Lonicerae, Elaeagnus Elaeagnus, Wisteria, Lysimachia christinae, Kumquat, Ilex cornuta, Concha Crassostrea, Mahonia latifolia, etc., all have a certain degree of shade tolerance.

In the conservation work, bonsai of positive plants must be placed in sunny places to meet their demand for light, but most positive plants should also be properly shaded in summer and high temperature seasons to avoid high temperature damage. When the positive plant bonsai is used for indoor display, it should be turned to outdoor regularly to receive sufficient light. The placement of shade plant bonsai must have shading conditions, avoid direct glare, and it is advisable to see sparse light. The light management of shade-tolerant plant bonsai may not be as strict as the first two, but it should generally be placed in a place with sufficient light, because "shade tolerance" and "shade preference" are different.

In addition, as positive plants, different plants have different requirements for light, such as peaches prefer light to grapes. Similarly, the degree of photophobia among negative plants and the degree of shade tolerance among shade-tolerant plants are different. Therefore, in light management, it is necessary to master the light demand characteristics of specific plant species to meet their light needs.

2. Lighting time

Different plant species also have different requirements for lighting time. Some bonsai plants are short-day plants, such as chrysanthemum and bougainvillea. Only when the day light time is reduced to less than 10 hour can these plants differentiate into flower buds, and only when their demand for short sunshine is met can these plants bloom normally. According to this. We can artificially create short sunshine conditions to control the flowering period.

(2) Temperature environment management

In the long-term evolution process, plants have chosen their own suitable temperature adaptation range. Each plant has its optimum temperature, maximum temperature and minimum temperature, that is, the temperature is three basis points. At the optimum point, plants grow well, and when they exceed the highest and lowest points, plants grow poorly and even die. Plants can generally grow in a wide temperature range of 0-35℃, growing faster with the increase of temperature and slower with the decrease of temperature.

The initial temperature of different plant species is different. For example, some tropical species start to grow above the daily average temperature 18℃, subtropical species start to grow at 15- 16℃, and temperate plants start to grow at 10℃ or even lower.

Different plant species have different degrees of tolerance to low temperature. Generally speaking, plant species native to temperate and cold regions can tolerate lower temperatures, such as -35℃ for apples and -20℃ for crape myrtle. Chimonanthus praecox can withstand the low temperature of-10℃. Plants native to tropical and subtropical regions are generally not hardy. For example, bougainvillea leaves at 4℃, bougainvillea and asparagus must be at 10℃ to overwinter, and camellia can only tolerate low temperature of about 0℃.

Generally speaking, the root system of plants has lower cold tolerance than its aboveground parts. For example, the above-ground winter buds of European grapes can withstand the low temperature of-16~- 18℃, and when the temperature is lower than -5℃, their roots will freeze. Taking potted plants as an example, the temperature environment of roots changes greatly and is more susceptible to low temperature. Therefore, when low temperature comes, the root system of potted plants is the most vulnerable part.

High temperature can cause plants to stop growing and even get hurt. The growth of general plants is gradually inhibited at 35-40℃. When the temperature rises above 50℃, most plants will die.

The key point of temperature environment management of bonsai plants is to prevent the damage of low temperature and high temperature to plants. In cold winter, especially in the north, cold-proof measures should be taken to ensure the safe wintering of bonsai plants. In the north, tropical and subtropical plants that are not hardy should be put in greenhouses for wintering, and the temperature should be kept above the lowest temperature that plants can tolerate. For cold-tolerant plants, because their roots are easy to be frozen, wintering protection must also be taken. Generally, the following cold protection measures can be taken:

1. Overwintering in a low-temperature greenhouse

Bonsai should be kept in a greenhouse at 0-5℃. If the temperature is too high, it will hinder the natural dormancy of plants and affect their growth.

Covering winter

Choose a place that is sheltered from the wind and sunny with good drainage. Dig an east-west cold-proof ditch before winter. The width of the ditch should be two rows of potted trees side by side, and the depth is generally the same as the height of potted plants. In cold areas, it should be buried deeply, and half of the roots should be left below the permafrost. After putting the basin into the ditch, pour enough water into the basin and the ditch, then cover the basin with grass and bury it with soil. The remaining soil can be piled up on the north side of the cold-proof ditch, or a windbreak wall can be set up on the north side to improve the microclimate of the ditch surface. This method is suitable for overwintering maintenance of deciduous fruit tree bonsai in northern China. When the soil thaws in early spring, the plastic film on the basin should be removed in time, unearthed as soon as possible, and replenished in time.

In the south of North China, pots in ditches can be covered with leaves and straw. And you don't have to bury it with soil, but you should pay attention to check the soil moisture and replenish it.

Step 3 spend the winter in the cellar

This method is suitable for deciduous fruit tree bonsai in cold areas. The temperature in the cellar is relatively high and stable, which can ensure the wintering safety of bonsai.

In South China, because the four seasons are warm and there is no frost, bonsai can generally overwinter outdoors, but it should be prevented from being harmed by the northwest wind.

Summer is a season prone to high temperature hazards, so shading measures should be taken in summer to avoid high temperature hazards, even for trees that like light, attention should be paid to shading. Shading shed has many forms and structures, which can be built based on local materials according to the requirements of tree species, so as to block direct sunlight, facilitate ventilation and receive scattered light. The shed height should be about 2 meters, which is beneficial to operation and management.

(3) Air environment management

The air environment also directly affects the growth and development of bonsai plants. The ideal air environment should be clean and pollution-free, well ventilated, with high air humidity and no wind damage.

Attention should be paid to prevention in areas with strong wind hazards. (From Floriculture)

Section 2 Maintenance and Management of Landscape Bonsai

The purpose of landscape bonsai conservation management is to preserve the landscape in the basin for a long time. Therefore, it is necessary to maintain the healthy growth of plants in bonsai and try to keep their existing shapes, and at the same time, clean and maintain the rocks to prevent them from being damaged. The maintenance and management of plants in landscape bonsai is basically the same as that in tree bonsai, but it is more detailed. The maintenance and management of landscape bonsai mainly includes the following contents.

I. Environmental management

Landscape bonsai should generally be kept in a semi-cloudy, warm and humid environment. Because the roots of plants in landscape bonsai are extremely shallow, they are neither drought-resistant nor cold-resistant. The good growth of moss also needs a semi-cloudy, warm and humid environment. In summer, direct sunlight should be avoided when placing bonsai outdoors. In northern winter, landscape bonsai should be moved indoors earlier than ordinary potted flowers and trees to prevent cold.

Second, water.

Generally, hard rock landscape bonsai should always water the plants on the stone. For soft stone landscape bonsai, in addition to storing clear water in the basin, water should be poured into the plants on the stone. In order to prevent white salt spots from appearing on the peak of soft stone bonsai, water can flow slowly into the basin from the peak along the hillside when watering.

Third, change the water and clean it.

The water stored in the basin should be changed regularly to keep the basin water clear and transparent. Wash the basin by the water, dry it and wax it to prevent sediment from polluting the basin bottom.

Four. Fertilization and modeling of plants

There is little soil in the roots of plants in landscape bonsai, so it is not easy to change soil in hole planting. Therefore, it is very important to pay attention to regular fertilization. Plants in landscape bonsai should also be reshaped in time, controlled in size, and kept in beautiful shape.

V. Protection of Rock

When moving bonsai, handle it gently and don't touch the peaks and foothills. In winter in the north, even landscape bonsai without plants should be kept indoors to prevent rocks from freezing and cracking. When the rock is damaged due to weathering, collision and other reasons, it should be reshaped, and the original state of the rock should be kept as much as possible.

Section 3 Maintenance and Management of Flood and Drought Bonsai

First of all, water

The pots used for flood and drought bonsai are very shallow, so special attention should be paid to timely replenishment. In order to prevent the basin soil from being washed away when watering, it is advisable to water it with a fine-eye watering can. When the climate is dry, you can spray it on the basin surface, trees and stones with a sprayer to keep the moss growing well.

Second, fertilization.

There is little soil and limited nutrients in flood and drought bonsai, so we should pay attention to fertilization to make trees grow healthily. Fertilization is sprayed on the soil surface with diluted organic fertilizer water. Granular organic compound fertilizer can also be buried in basin soil.

Third, change the soil

Trees in flood and drought bonsai usually change once every 3-5 years, mostly in spring and autumn. When changing soil, first remove some stones and accessories (pay attention to the position), carefully pull out the trees with soil, remove the old soil with bamboo sticks 1/2, cut off the dead roots and some old roots, replace them with new soil, plant them in pots according to their original positions, put on accessories, and spread moss.

Four. Placement and protection

Usually put it in a ventilated and light-transmitting place. Avoid being exposed to the sun in summer. In winter, you should move to a place with plenty of light indoors, so you can't get cold. In the growing season of plants, be careful not to stay indoors for many days, so as not to affect the growth.

The pest control of flood and drought bonsai is the same as that of ordinary tree bonsai.