What to do when bougainvillea leaves turn yellow? Find the cause; water and fertilizer management is key
For bougainvillea, friends who have seen it should be deeply impressed. Its bracts are large, its flower colors are rich, and its flowering period is long, giving it extremely strong ornamental value, and it is kept in many flower lovers' homes. However, during the care of bougainvillea, improper care can cause the leaves to turn yellow, so what should be done when bougainvillea leaves turn yellow? Below are several causes of yellowing bougainvillea leaves compiled by the editor. Let's take a look together.
I. What to do when bougainvillea leaves turn yellow: find the cause
The beauty of bougainvillea inspires affection. Its green leaves and fiery red flowers set each other off beautifully and are very pleasing to the eye. However, once improper care causes bougainvillea leaves to turn yellow, it will seriously affect the ornamental value. What should be done then? Actually it is very simple: find the cause and solve it. Below are 6 causes of yellowing bougainvillea leaves, along with solutions. Let's continue reading.
II. Six causes of yellowing bougainvillea leaves
1. Soil does not drain
There are many causes of yellowing bougainvillea leaves, but the first thing to consider is the soil. In bougainvillea cultivation methods, it was once introduced that although bougainvillea does not have high soil requirements, it fears waterlogging and is not tolerant of waterlogging, so loose, well-drained soil must be chosen. Therefore, once the soil is very compacted and does not drain, over time the phenomenon of yellowing leaves will appear.
Solution: If the yellowing of bougainvillea leaves is caused by improper soil selection, then you should change the pot and soil, and choose a loose, well-drained growing medium: humus soil, garden soil, and sand mixed in a 4:4:2 ratio.
2. Overwatering
As mentioned earlier, bougainvillea fears waterlogging, so once we water too much and cause water to accumulate in the pot, yellowing bougainvillea leaves will appear.
Solution: When there is too much watering, stop watering immediately and loosen the soil more to let the water evaporate; in normal watering, pay attention: in spring and autumn water once a day, in summer once each in the morning and evening, and in winter the plant is in a dormant state, so water less and just keep the potting soil moist.
3. Overfertilizing
After watering, let's look at fertilizing. It is also one of the causes of yellowing bougainvillea leaves. During the growth of bougainvillea, fertilizing is essential, but when it grows slowly, fertilization should be stopped. If it is still fertilized at this time, it will cause fertilizer burn, leading to root rot and yellowing leaves.
Solution: When bougainvillea grows slowly or is dormant, fertilization should be stopped to avoid fertilizer burn. If too much fertilizer has been applied, it is best to change the pot and soil immediately so that the bougainvillea becomes dry and fresh again, and after a period of care it will recover.
4. Insufficient light
Flower lovers who have grown bougainvillea all know that bougainvillea cannot lack light. Once the light duration is too short, its branches will become thin and weak, the leaves will also turn yellow, and in severe cases it may even die.
Solution: Increase light and give bougainvillea sufficient light duration. If placed indoors, it is best to choose a place with abundant sunlight. In winter it should be placed in front of a south-facing window, and the light duration must not be less than 8 hours, otherwise a large number of leaves may fall.
5. Disease: leaf spot / brown spot
Besides the above points, diseases must also be considered as causes of yellowing bougainvillea leaves. Once bougainvillea suffers from leaf spot or brown spot, yellow or brown diseased spots will appear in the early stage, the spots will gradually expand, and the leaves will gradually fade and fall off.
Solution: Spray relevant agents. As for the specific method, it is introduced in detail in bougainvillea pest and disease control, so it will not be discussed further here. But to avoid unnecessary trouble, in normal care you should strengthen ventilation and maintain leaf humidity to avoid damage from pests and diseases.
6. Sudden environmental change
If the above points can be ruled out, then there is one more cause of yellowing bougainvillea leaves, namely sudden environmental change. This situation is generally found in flower lovers who bought bougainvillea online. It may be because the growing environment changed greatly all at once and it did not adapt. After being kept for a period of time, symptoms of yellowing and drying leaves will appear.
Solution: At this time you should communicate with the seller to understand the bougainvillea's previous growing environment. At home we should try to keep conditions unchanged as much as possible, then change them gradually until it adapts. After a period of time, the flower lovers' bougainvillea will recover its health.
Overall, bougainvillea is very easy to grow, but growing it well is obviously not easy. Once there is the slightest negligence, its leaves will turn yellow, thus affecting the ornamental value, so everyone must not be careless for a moment. Regarding the causes of yellowing bougainvillea leaves, the editor will introduce them here. Finally, may everyone's bougainvillea bloom beautiful flowers~
What to do when clivia and gardenia do not bloom
Floral Bonsai Network introduction: Today the editor of Floral Bonsai Network brings you an article on what to do when clivia and gardenia do not bloom. Let's take a look.
Many people like to grow flowers, but I believe many people will have all kinds of problems after buying them home. Among them, the most common and most widespread problem is none other than: why do the flowers I grow not bloom?
In fact, there are many reasons why flowers do not bloom. Apart from the plant itself being weak in growth (or not having reached the conditions for blooming), other possible reasons affecting plants not blooming or blooming little include: insufficient light, poor ventilation, unsuitable temperature, unsuitable soil pH, improper pruning, insufficient nutrients, too much nitrogen fertilizer, pests and diseases. Today I will share treatment methods for several common flowering plants that do not bloom:
I. Clivia does not bloom
1. Too much light: If clivia is exposed to the sun for too long in summer, it will cause the leaves to grow excessively (that is, abnormal, unhealthy rapid growth), leading to the consumption of a large amount of nutrients in the plant, thereby affecting clivia's bud formation and preparation for blooming in winter. Clivia is suitable for places with a little scattered light, and growing it by a windowsill is very suitable.
2. Temperature too low: If the temperature in the place where clivia is grown is too low, if it is below 10°C, then clivia's growth will be inhibited, and below 5°C it basically stops growing, let alone making clivia send up a flower stalk and bloom; even the plant will appear thin, small, and yellow. Maintaining an appropriate temperature for clivia in winter is very critical.
3. Insufficient nutrition: What clivia fears most is compacted soil without permeability. If you have not changed the pot since you bought the clivia, that means it is difficult for the clivia roots to absorb water and nutrients, which will directly cause it not to bloom and only grow leaves. Clivia should be repotted and the soil changed once a year after flowering.
4. Insufficient fertility: If fertilizer is not applied in time, it will certainly affect clivia's growth condition. If nutrients are not even enough, how can it bloom? Giving clivia an appropriate amount of decomposed cake fertilizer as base fertilizer is very critical. Next, do not apply fertilizer frequently in spring and autumn; only in this way can soil fertility be maintained, making blooming easier, and the plant and root system will also grow stronger. In late autumn, you can spray clivia with an appropriate amount of monopotassium phosphate, which is to promote flower bud formation.
II. Gardenia does not bloom
1. Insufficient light: Gardenia likes a warm, bright, sunny, and well-ventilated environment. Move the gardenia to a place with good light and let it get some sun appropriately.
2. Potting soil too alkaline: Gardenia likes slightly acidic humus soil. A pH of about 4.8~6 is most suitable. If the soil is alkaline, the leaves will turn yellow. When watering normally, you can add some ferrous sulfate to improve the soil quality, and you can also often apply 10% alum fertilizer water as a top dressing.
3. Insufficient fertility: Gardenia likes fertilizer. During the growing season, apply decomposed cake fertilizer as a top dressing; before the flowering season, apply phosphorus and potassium fertilizer; during the flowering period, do not fertilize. It is recommended to change the soil once every 1~2 years to maintain soil fertility.
III. Aglaia does not bloom
1. Soil too alkaline: Aglaia likes slightly acidic soil. If cultivated with alkaline soil, or often watered with alkaline water, it will not only affect flowering but can easily lead to death. You can water with prepared alum fertilizer water once every 10 days.
2. Insufficient nutrition: During the growing season, appropriately supplement some cake fertilizer, alum fertilizer water, etc.; before the flowering season, reduce nitrogen fertilizer and supplement phosphorus and potassium fertilizer; during the flowering period, do not fertilize; after flowering, supplement phosphorus fertilizer.
3. Insufficient light: Aglaia likes sunlight. If it is too shaded, it will also affect flowering. It is necessary to move the Aglaia to a place with good light and let it get some sun appropriately.
IV. Bougainvillea does not bloom
1. Insufficient light: Bougainvillea is a light-loving plant. If there is insufficient light or it is too shaded, new branches will grow thin and weak, leaves will be thin, and flowering will be sparse and small. Bougainvillea must be placed in a location with sufficient light and good ventilation, and given 8 to 12 hours of light each day.
2. Improper watering: Do not water before the bougainvillea flowering period; control water appropriately. If watered too much, it will affect flower bud differentiation and make blooming difficult. You need to wait until the leaves wilt before watering.
3. Improper fertilizing: Bougainvillea likes fertilizer and water, and fertilizing should be generous, because bougainvillea blooms abundantly, has a long flowering period, and consumes much nutrients. In addition, there is not much potting soil, so nutrients are limited, and nutrients need to be replenished in time. If nutrients are insufficient and water and fertilizer conditions cannot keep up, flowering will be delayed, flower quantity will be small, and the flowering period will also be short. According to the size of the pot, generally once a month; during the vigorous growth period of bougainvillea, apply liquid fertilizer once every half month; when the environmental temperature is higher, more can be applied. Applying more phosphorus and potassium fertilizer is beneficial to flower bud differentiation and ensures robust flower buds.
4. Branches too dense: Bougainvillea has vigorous vitality and will become as dense as a forest in a few months, but the soil and nutrients in a pot are very limited, and the growth space is also limited. If overly dense branches are not pruned in time, it will cause excess nutrient loss, affect flower bud differentiation, and make blooming difficult. It is necessary to prune off weak branches, dead branches, and some useless branches of bougainvillea.
Introduction to the causes, symptoms, and control methods of cold damage in flowers and trees
Cold damage in flowers and trees is a physiological disease. It generally refers to damage caused by low temperature acting directly on the plant, including chilling injury and freezing injury, but not including indirect winter drought, frost heaving, and other winter damage. It generally occurs in late autumn and early winter when a cold wave suddenly moves south, or because of the sudden arrival of the "first frost," which can easily cause plants to suffer chilling injury or freezing injury; in spring, when potted flowers are moved out of the house or when the covering film is removed from facility-cultivated flowers and trees, a sudden encounter with the late-arriving "late frost" or "late spring cold" may also very likely cause the plants to suffer chilling injury or freezing injury again. The causes of cold damage differ, and the harm they bring also differs. The differences between cold damage and general infectious diseases are: first, it is not contagious and no pathogen appears in the damaged parts; second, the same kind of flower and tree placed in the same environment often shows disease overnight at the same time, and tender shoots and new leaves are the most serious; third, it occurs under low temperature or particularly cold weather conditions, and the harm is related to the species of flower and tree, the length of duration of low temperature, the speed of temperature recovery, and the lower limit of low temperature.1. Causes of chilling injury: Some ornamental plants native to tropical or subtropical regions suffer severe damage to or death of plant tissue structure due to the influence of low temperatures above freezing (0°C~5°C or somewhat higher) for several days or even just a few hours. This kind of cold damage that has not reached the degree of freezing inside tissues is called "chilling injury." It is damage formed because normal metabolism inside cells is disturbed and disrupted, tending toward disorder and producing toxic substances. Different physiological activities and metabolic processes of plants each have their own maximum, minimum, and optimum temperatures. When the environmental temperature changes, their physiological activities and metabolic processes will all be affected differently; if a certain range is exceeded, the coordinated relationships among them will be destroyed, producing large amounts of substances that would not be produced and accumulated under normal conditions. Further research found that under chilling injury conditions, the rate of protein hydrolysis increases by 4~9 times compared with normal conditions; nucleic acid metabolism is also severely disturbed; in addition, temperature decrease also affects the oxidative activity of sensitive mitochondrial membranes in plant cells.
From this it can be seen: first, the ornamental plant species that suffer chilling injury are usually plants native to tropical or subtropical regions; second, the temperature condition for chilling injury is damage from low temperatures above freezing; third, the time that causes chilling injury may be long or short, usually several days or even just a few hours. Generally, sudden changes in temperature in late autumn and early winter or early spring are most likely to cause chilling injury in flowering and foliage ornamental plants native to tropical or subtropical regions. It usually manifests as overly tender new shoots and young leaves "turning purple," "turning brown," "turning yellow," "wilting," "necrosis," etc., such as frost-struck scarlet sage, bamboo-leaf foliage plants, kalanchoe, bougainvillea, purple bamboo leaves, and so on, all belonging to this category.
2. Causes of freezing injury: Freezing injury refers to damage caused by ice formation inside the tissues of ornamental plants in an environment below 0°C or when encountering sustained ultra-low temperatures for a long time.
There are two situations in which ice crystals appear inside plant tissues: one is freezing inside cells, and the other is freezing between cells. The former refers to when plant tissues freeze very quickly, ice crystals form in vacuoles and protoplasm, destroying the structure of the protoplasm and causing protein denaturation. Some membranes within the protoplasm are also torn, usually leading to killing of the tissue, so the result of this kind of "freezing injury" is very severe and irreversible. For example, in early winter when a cold wave from the north suddenly moved south, causing a large temperature drop in a short time, in the winter of 2004 this caused large numbers of foliage plants in southern China to die from freezing injury; in early December 2005, in the Hefei area, the temperature suddenly dropped from 12°C~15°C to -3°C~-5°C, causing severe freezing damage to the leaves and young stems of large numbers of field-planted magnolia family flowers and trees such as Guangnan manglietia, Yunshan white magnolia, red-flowered manglietia, and Ruyuan manglietia. The latter refers to ice crystals gradually forming inside plant tissues as the environmental temperature gradually decreases. Because the solute concentration in the intercellular spaces is generally lower than that of the protoplasm and vacuolar fluid, when the cooling rate is not too fast, the water in the intercellular spaces reaches freezing point and freezes before the interior of the cells. The formation of ice crystals also causes water in the protoplast to move outward, thereby causing cell sap concentration, protoplasm dehydration, protein precipitation, cell membrane denaturation, and cell wall rupture; when ice crystals form in the intercellular spaces, whether the cell tissue is killed depends on the cold resistance of the cells and the speed and number of times of freezing and thawing; one of the mechanisms of freezing injury is protoplasm dehydration, and its consequences are the same as dehydration under drought conditions, namely that mechanical stress produced by deformation of the cell wall causes irreversible damage to the protoplasm structure; after cell sap concentration, increased concentrations of salt ions and organic acids may also poison the protoplasm. The severity of freezing injury is related to the speed of freezing. The faster the freezing, the more severe the damage, because when freezing is fast, the possibility of intracellular freezing is greater; if freezing is limited only to the intercellular spaces, then the faster the freezing, the faster the cells lose water and shrink, and the greater the destructive effect of the resulting mechanical stress. The severe consequences of freezing injury are also related to the thawing speed of frozen tissue. Generally, in the case of intracellular freezing, tissue necrosis is inevitable and unrelated to the thawing speed of freezing; in the case of intercellular freezing, the faster the thawing, the greater the damage, because the cell wall rapidly absorbs water produced by melting ice and expands, but the protoplasm attached to the cell wall absorbs water more slowly and is thus torn and damaged. For example, after severe freezing, red bellflower and bougainvillea die because the bark is torn as the temperature rises rapidly.
Ornamental plants suffering cold damage show the following specific symptoms:
1. Xylem blackening: Among the various tissues of mature branches of woody flowers, the cambium is the most cold-resistant, followed by the phloem, while the xylem and pith are the least cold-resistant. Therefore, slight freezing injury shows only pith discoloration, moderate freezing injury shows xylem discoloration, and only severe freezing injury freezes and damages the phloem. If the cambium in the stem or branches becomes discolored, it will lose the ability to recover and may cause the whole plant to die.
2. Bark cracking and necrosis: Some flower and tree species native to tropical and southern subtropical regions whose bark contains a relatively high water content, such as Chinese hibiscus, red bellflower, fagraea, cinnamon, money tree, crown of thorns, and small-leaved banyan. When the environmental temperature drops to around -3°C, not only will the leaves and branches be frozen to death, but even the outer bark of the stem, especially the root crown area, will crack and become necrotic due to water in the tissues forming ice crystals and cold expansion and heat contraction, and even the whole plant may die.
3. Changes in the color of tender shoots and new leaves: first, "turning yellow." In cold seasons, because the temperature is too low, the leaves of some flowers that require higher overwintering temperatures will also turn yellow or even fall off due to cold damage, such as anthurium, spider plant types, trailing green pothos, and watermelon peperomia; second, "whitening." For example, spider plants, amaryllis, and variegated inch plant placed or planted outdoors, when encountering lower temperatures, the new shoots and tender leaves will lose their original luster and show abnormal changes of "whitening and loss of green"; third, "scorching." The new shoots and tender leaves of some ornamental plants suffer damage such as frost, and the new leaves appear "scorched," such as spider plant, clivia, and Japanese aralia; fourth, "turning purple." Some ornamental plants show "purple-brown" leaf tips or leaf margins under low temperature conditions, such as money tree, cymbidium, and camellia (new leaves).
4. New shoots and tender leaves as if scalded by boiling water: Some ornamental plants with high water content in leaves, new shoots, or stems, including some succulents such as pothos, fagraea, Chinese hibiscus, Rieger begonia, Callisia, clivia, taro, aloe, kalanchoe, broadleaf lady palm, Canary Island date palm (seedlings), Washington fan palm, money tree, and giant taro. When the environmental temperature suddenly drops from 5°C~8°C to below -3°C~-5°C and lasts for a long time, their newly sprouted tender branches and leaves look as if scalded by boiling water or cooked, all dying in a short time, and the bark cracks and peels off.
5. New shoots and tender leaves brown, withered, and necrotic: The new shoots and tender leaves of some ornamental plants that are not fully developed, such as small-leaved banyan, mahonia, Japanese aralia, oleander, money tree, and cycad, look as if burned by fire and are very unsightly.
6. Plant body necrotic and hollow: Generally, succulents often become shriveled and hollow throughout the plant after freezing injury. Such as cactus balls, cacti, Euphorbia, and three-angled cactus. To protect ornamental plants from cold damage, the following methods can be used for prevention and control:
1. Prevention of cold damage in ornamental plants
(1) Choose relatively cold-resistant flower species
Flower lovers should choose foliage, flowering, or fruiting flower and tree species according to the lowest temperature in normal years in your area or the highest room temperature that can be maintained at home in winter (generally 5°C~6°C); in the Yangtze River basin, under conditions without heating equipment at home, you can choose camellia, sasanqua, jasmine, white orchid, clivia, Belgian azalea, plum blossom, wintersweet, finger citron, bitter orange, anthurium, sago cycad, etc.; you cannot choose croton, maranta, nerve plant, desert rose, Oxalis, Polyscias, Phalaenopsis, Dieffenbachia 'Marianne', arrowhead plant, money tree, etc.
(2) Carry out cold resistance training in stages
Generally, potted Japanese white pine, black pine, Japanese red pine, Huangshan pine, papaya, Chinese elm, trident maple, plum blossom, camellia, ginkgo, dragon juniper, Chinese arborvitae, Chinese juniper, etc. can be considered for overwintering in the ground. It is best to wait until the current year's growth has ended and then carry out cold resistance training in several stages. The first stage is 0°C~6°C, requiring several days to several weeks of sufficient light. For evergreens, this can make starch in the leaves convert into sugar, and large vacuoles divide into several small vacuoles. Some fat tree species can convert starch into fat; the second stage is -3°C~-5°C, in which the fine structures and enzymes within the protoplasm reorganize so that the cells can endure dehydration caused by freezing; the third stage is between -10°C~-15°C, enabling the protoplasm to acquire stronger freezing resistance, thereby passing through the cold winter. Some cold-intolerant succulent plants, such as if placed on a balcony or maintained outdoors for a long time and having a process of gradual adaptation, such as rat-tail cactus, Haworthia, jade plant, and jade plant, can increase from resisting low temperatures of 0°C to a low temperature level of resisting -5°C~-7°C.
(3) Strengthen cold-resistant cultivation management
After the Mid-Autumn Festival, control the water and fertilizer supply of potted ornamental plants. Appropriately increase phosphorus and potassium fertilizer to promote lignification of branches and full tissue development, enhancing their cold resistance. For example, you can pour or spray a 0.3% monopotassium phosphate solution. Pruning in winter or manually removing some leaves (such as white orchid) to reduce transpiration area can produce good results in preventing low-temperature damage. Strengthen pest and disease control to promote robust plant growth without autumn shoots or tender shoots.
(4) Protect the tree body from freezing
For field-planted tall camellia, osmanthus, banana shrub, southern magnolia, Canary Island date palm, sago cycad, etc., the main trunk can be bound with straw rope or film, the trunk can be whitewashed, or the crown can be sprayed white (7%~10% lime milk); the crown can also be covered and bound with plastic film, or wax preparations or liquid plastic can be sprayed, all of which can have a certain anti-freezing effect.
(5) Artificial heating to drive away cold
For potted plants placed in a greenhouse, in particularly cold weather an electric heater or coal stove can be used inside the greenhouse for heating, especially at 5~6 o'clock in the morning, the coldest time of the day, when heating must be emphasized; outside the greenhouse, add straw curtains or felt blankets for insulation. Generally at home, double-layer plastic bags can be put over the plants; for indoor potted flowers, if conditions permit, turn on the air conditioner from about 6 a.m. to about 10 p.m. to avoid chilling injury to anthurium, maranta, clivia, Phalaenopsis, Oncidium, cymbidium, Cymbidium hybridum, etc. For field-planted camellia, osmanthus, banana shrub, and other flowers and trees, water can be sprayed on the crown at dawn when frost is about to occur, or frost-prevention smoke agents can be lit before morning frost to effectively prevent "radiation frost."
(6) Delay sprouting to prevent late frost
Use growth regulators or other methods to prolong plant dormancy and delay sprouting, which can avoid frost caused by early spring cold wave attacks. For example, before budding or in late autumn, spraying field-planted plants with B9, ethephon, maleic hydrazide, potassium naphthaleneacetate (250mg/kg~500mg/kg) or maleic hydrazide (0.1%~0.2%) solution all have good effects. If potted flowers encounter "late frost" after being moved out of the house, they can be covered with large double-layer plastic film and uncovered after the daytime temperature rises.
2. Rescue and treatment of cold damage in ornamental plants
(1) Reasonable pruning
For plants that have suffered cold damage, reasonable pruning measures should be taken, and heavy pruning should not be carried out, otherwise harmful side effects will occur. So how can the pruning amount be properly controlled? It is necessary both to cut the damaged organs back to healthy parts to promote branch renewal and growth, and to ensure relative balance between aboveground and underground organs. Generally, if pruning immediately after damage, 1cm~2cm of the damaged branch can be retained to prevent the healthy branch part from shrinking downward again; if pruning after spring begins, it can be cut back to healthy parts to facilitate wound healing; practice has proved that properly pruned damaged plants recover faster than heavily pruned or unpruned plants.
For general evergreen potted woody flowers and foliage plants, all dead parts should be cut off in time and the plants moved to a relatively warm environment.
(2) Protect and repair wounds
For large plants with freezing damage only to a local part of the trunk base (northwest direction), the necrotic part can be cut out, wound healing agent applied, and then wrapped and protected with film to create a relatively warm small environment for them; for some damaged bonsai plants, they can be remedied by bridge grafting or approach grafting to replace roots.
(3) Strengthen pest and disease control
After ornamental plants suffer low-temperature damage, because their tree vigor is relatively weak, they are highly susceptible to pest and disease invasion. Chemical agents can be applied in combination with freezing damage control. Among them, fungicide plus moisture-retaining adhesive has a relatively good effect, followed by fungicide plus high-fat film. Both are better than simple fungicide or whitewash. Because the main agent fungicide can only play a role in surface disinfection and sterilization, while the auxiliary agents moisture-retaining adhesive and high-fat film both retain moisture and increase temperature, all of which are beneficial to the formation of callus tissue in cracked bark and thus promote healing of freezing injury.
(4) Fertilize cautiously
For plants that have suffered freezing damage, after overwintering, high-concentration chemical fertilizer should not be applied immediately. Instead, wait until the temperature rises and the root system recovers its absorption function, then spray or pour low-concentration liquid fertilizer. For example, alternately spraying or pouring 0.3% monopotassium phosphate and 0.3% urea solution has very good effects.