How to water flowers reasonably? Practical irrigation tips shared
(1) The effect of water on flower growth and development
Water is vital to all living things. Flowers are no exception. Water makes up 40%-95% of the fresh weight of common grasses and herbaceous flowers. Like temperature and light, water is a basic living factor indispensable for the survival and reproduction of flowers. Moisture conditions have a great influence on the growth, development, reproduction and dormancy of flowers, and even on changes in temperature and humidity in the site environment, as well as the occurrence and damage of pests and diseases. The main roles of water in flower growth are:
(1) Water is the main raw material for photosynthesis in flower plants. About 0.6 kg of water is needed to synthesize 1 gram of organic matter.
(2) Water is a solvent. The nutrients needed for flower growth and reproduction must all be dissolved in water before they can be absorbed by the flower root system.
(3) Water is a medium. Respiratory oxidation and various complex enzymatic biochemical reactions in the flower body must all take place in an environment with water and with the participation of water.
(4) Water is the medium and driving force of transport. Flowers rely on water transpiration to maintain normal temperature and maintain the water balance in the plant body. About 98% of the water absorbed by plants is used for transpiration, and only 2% remains in the body and is used to build the plant itself. No wonder a medium-sized annual flower needs to consume about 50 kg of water during its short life cycle of 4-5 months.
Water is an important guarantee for maintaining the normal life activities of cell protoplasm. The continuous renewal and exchange of water can maintain normal osmotic pressure in the plant body and keep flowers in a turgid state. For example, the standing of flower stalks, the spreading of leaves, and the opening of flower buds are all inseparable from water.
Water content also directly affects the growth and development of flowers. For example, too much water can cause excessive vegetative growth, inhibit flower bud differentiation, and also lead to root rot and disease. Too little water will damage the water balance in the plant body and cause flowers to wilt. Flower seeds can germinate only in a moist environment. A water content below 13% is a necessary condition for the safe storage and stable dormancy of most seeds. Overwintering, summering and dormancy of flowers also require good coordination with suitable moisture conditions. Soil water content has three different suitable states for any cultivated flower. At the most suitable state for survival, the water content at this time can effectively maintain the dynamic balance of water income and expenditure in the plant body and promote vigorous growth. When it is higher than the maximum water content that flowers can tolerate, excessive soil water and lack of oxygen will cause root rot or death by suffocation. If it is lower than the minimum water content that flowers can tolerate, the roots cannot absorb enough water, so growth stagnates, flower buds drop, and finally the plant gradually loses water, dries up and dies.
The amount of soil water content has a great influence on air humidity, and therefore also indirectly affects flower growth. If air humidity is too high, it has adverse effects on flowers, often causing excessive growth of branches and leaves and becoming a cause of flower drop. Also, because the plant body grows weakly, its resistance to pests and diseases decreases. At maturity, excessive humidity hinders plant flowering and affects stability. However, among greenhouse plants, many varieties like relatively high air humidity. For example, many tropical foliage plants are instead affected in their growth if humidity is too low. While these plants like humidity, they also require suitable temperature. If temperature cannot match, humidity should also not be too high.
Water content not only affects the normal growth of flowers, but also affects flower bud differentiation and flower color. In flower cultivation, methods such as reducing water and cutting off water are often used to promote flower bud differentiation. For example, greenhouse-cultivated Dendrobium (an orchid family plant) should undergo short-term water cutoff starting in mid-October to promote flower bud differentiation; otherwise it often fails to bloom. For bulb flowers, water is often the main factor determining the timing of flower bud differentiation. For example, according to experiments on tulip flower bud differentiation, the lower the water content, the earlier the differentiation. Bulbs produced in sandy land differentiate earlier because of low water content. Bulbs dug early have high water content, so the differentiation period is delayed.
Flower color is relatively closely related to water, and only suitable humidity conditions can bring out the inherent color of each variety. Usually when water is lacking, flower color becomes more intense. For example, white and light pink varieties of rose often become cream yellow or deep pink when water is insufficient; the same situation also occurs in chrysanthemums. Experiments confirm that when water is insufficient, color becomes more intense because more pigment is formed.
(2) Water requirement patterns of flowers
Because of differences in the moisture environment of their places of origin, various flowers have different water requirements, and the environmental conditions suitable for their growth are also not the same. They have also formed different adaptive methods in morphology and physiological structure. For example, cactus plants native to the desert areas of the Americas, in order to adapt to the dry environment there with extremely sparse rainfall and to reduce water evaporation, have leaves that became strongly reduced and turned into needle-like forms over the long course of evolution, and they have a very thick cuticle and wax layer covering, which helps keep water in the body from evaporating. Even if no water is supplied for several years in a row, they can still survive tenaciously. In contrast, most evergreen flowers from warm and humid regions have large, thin leaves, tender tissues, no dense and thick wax layer or cuticle protection, and stomata that are often open, causing large amounts of transpiration, which is very unfavorable for storing water in stem and leaf organs. In order to maintain water balance in the plant body, they need a regular and sufficient supply of water.
According to the water requirement habits of flowers and their ability to adapt to different moisture environments, common flowers are divided into the following types:
1. Aquatic flowers. They must grow in water. Their vegetative organs have highly developed aerenchyma that can continuously transport oxygen. Such flowers include lotus, water lily, Acorus gramineus and so on.
2. Wetland flowers. They can grow in soil that is often saturated with water or in environments with high air humidity, and they have relatively strong waterlogging resistance. Such flowers include narcissus, butterbur, ferns, Monstera deliciosa, Cyperus alternifolius, Alocasia, Guangdong evergreen, Impatiens walleriana, Commelina communis and so on. Because their leaves are large and thin, tender and succulent, with a thin cuticle and inconspicuous wax layer, and their root systems are shallow with few branches, they often look poor or even die in dry and low-humidity environments. They are suitable for growing in environments with sufficient water supply and very high humidity. During maintenance, the watering principle of preferring wet over dry should be followed.
3. Mesophytic flowers. They are suitable for growing under conditions of moist soil and good drainage. Both overly dry and overly wet environments are unfavorable to their growth. Their drought tolerance lies between xerophytic and hygrophytic, with some variation depending on species and variety. For example, osmanthus, white magnolia and crabapple are relatively drought tolerant, while wintersweet, oleander and winter jasmine are relatively moisture tolerant, so water management cannot be completely the same. Usually a soil water content of 60% can be maintained. For flowers that like lower soil moisture and higher air humidity, during maintenance water should be continually sprayed into the air or the humidity of the surrounding ground should be increased.
4. Xerophytic flowers. Most of them originate in arid desert areas and have formed unique morphological structures adapted to dry climate ecological environments, such as small leaves or reduced leaves, sunken stomata, succulent stems, and well-developed root systems. Such flowers include cacti, Echeveria, Euphorbia milii and so on. In cultivation and management, the watering principle of preferring dry over wet should be followed. Too much watering and excessively high air humidity are instead likely to cause root rot and damage from anthracnose, blight and other diseases.
The water requirements of flowers for soil moisture differ at different growth and development stages. Generally speaking, after sowing, relatively high soil moisture is needed in order to moisten the seed coat, make the seed coat expand, and help the radicle and plumule germinate. After the seeds germinate and emerge from the soil, the root system is relatively shallow and the seedlings are very slender and weak, so the surface soil should be kept moderately moist. Afterward, in order to avoid excessive growth of seedlings and promote plant maturity, soil moisture should be reduced, which is the so-called "seedling hardening." Hardening seedlings at the seedling stage is one of the effective methods for cultivating strong seedlings. When growth reaches a certain point, relative drought (called "water withholding" or "water control" in flower cultivation) can also make branches stop growing faster and accumulate nutrients for flower bud differentiation. Flower bud differentiation is the turning point from vegetative growth to reproductive growth. At this time, properly controlling water for plum blossom, peach blossom, Prunus triloba, kumquat, crape myrtle, redbud and so on, and watering less or stopping watering several times, can inhibit or delay stem and leaf growth, advance and promote flower bud formation and development, thereby achieving the ornamental goal of abundant flowers and heavy fruit. However, during the flowering period of flowers, the supply of soil moisture should be maintained at an appropriate level. Too little water results in poor flowering and shortens the flowering period, while too much water can also cause flower and bud drop. In addition, air humidity also affects flowering. Too low humidity shortens the flowering period and prevents the display of various inherent flower colors. But too high humidity can also cause petal mildew and the spread of pests and diseases.
Overall, the water requirement characteristics of flowers are as follows: water demand increases during seed germination and seedling growth stages; sufficient water is necessary during the stem and leaf vegetative growth stage; water supply should be appropriately controlled during flower bud differentiation; water demand is greatest when entering the bud and flowering stages; and water demand is again lower during the later fruit and seed maturation stage. Therefore, watering should be carried out according to the water requirements of flowers at each developmental stage, so that flowers grow vigorously, with luxuriant branches and leaves, lush green beauty, and a splendid appearance.
(3) Reasonable watering of flowers
Most of the water needed for flower growth is absorbed from the soil. Maintaining appropriate soil water content is a necessary condition for the normal development of flowers and for obtaining higher ornamental quality. Because flower cultivation methods differ, there are certain differences in irrigation amount and irrigation time.
1. Reasonable watering of field-grown flowers. Watering field-grown flowers is relatively easy. In rainy areas, attention should be paid to drainage in production, especially timely drainage after rain. If there is a long drought without rain, appropriate irrigation is also needed to maintain soil moisture, prevent the soil surface from cracking, and avoid tearing the root system. Field planting should never use flood irrigation. Where conditions permit, parks and gardens may use sprinkler irrigation and drip irrigation.
In the arid and water-scarce north and in water-scarce seasons, in addition to taking drought-resistance measures, appropriate irrigation must be carried out in a timely manner according to rainfall conditions to meet the water needs of flowers and trees during growth and development.
The amount and frequency of irrigation for field-grown flowers and trees mainly vary according to flower species, growth and development stage, weather, and soil quality. Irrigation should be controlled according to soil dryness and wetness. In specific operations, attention should be paid to the following points:
(1) Irrigate according to the growth season of flowers. Looking at the whole year, summer has high temperatures and large evaporation, so more irrigation is needed. In winter, field-grown plants usually stop growing and temperatures are lower, so irrigation should be reduced, and if the soil is not dry, do not irrigate. Looking at a single day, irrigation is usually carried out in the morning, but in summer, because water evaporates quickly, another irrigation is needed around 4 p.m. In winter, morning temperatures are low, and irrigation at that time is instead unfavorable, so it is best to irrigate at 10-11 a.m.
(2) Irrigate according to plant species and growth period. Broadleaf and moisture-loving plants should be watered more; small-leaved, needle-leaved and cactus plants should be watered less. At the seedling stage, water less; when entering vigorous growth and flowering stages (for fruit-viewing types), water more; when seeds mature, water less; and during dormancy, water even more sparingly. In addition, the leaves of Gloxinia and African violet and the flower buds of African daisy are all prone to rot after being watered. These special situations all require attention.
(3) Judge irrigation amount and frequency according to soil quality. Sandy soil has large porosity, strong water storage capacity, and is prone to dryness rather than waterlogging, so it is suitable for more irrigation. Clay soil is "a mess when wet, a knife when dry." While paying attention to preventing waterlogging, also pay attention to preventing drought, carry out timely intertillage and loosening of the soil, appropriately reduce the number of irrigations, and increase the amount of water each time as appropriate. Humus soil rich in organic matter is loose in texture and has a large water-holding capacity. It is neither too prone to drying nor too prone to waterlogging. Under the same conditions, both irrigation amount and frequency can be correspondingly reduced.
2. Reasonable watering of potted flowers. Watering potted flowers has similarities with watering field-grown flowers. Both must consider water quality and water temperature, and must also choose appropriate watering timing and amount according to the moisture and temperature requirements of various plants, their growth and development stage, their current growth vigor and appearance, and weather changes, "watering by observing the sky and watering by observing the flowers." The root system of potted flowers is limited to a certain space, so watering is more complicated than for field-grown plants. Potted flowers should also pay special attention to "watering by observing the pot."
(1) Watering by observing the sky mainly means deciding whether watering is needed and how much water is needed according to changes in season and weather. In specific operations, attention should be paid to the following points:
① Observe the season: In spring, temperatures rise, flowers and trees wake from dormant sleep, leaf buds sprout rapidly, some flower buds begin to grow, and the water demand of potted flowers begins to increase. Especially in the north, where spring drought and wind are common, the first watering after potted flowers are moved outdoors must be thorough. Afterward, as spring temperatures gradually rise, the plant's vegetative body expands, and transpiration and evaporation strengthen, the number of waterings should gradually increase and the interval between two waterings should be shortened. Usually it can change from watering once every 2-3 days in early spring to watering once every 1-2 days. Spring-sown annual flowers and trees are at the sowing and emergence stage at this time, with small seedlings and relatively slow growth, so they consume little water. Watering too much at ordinary times will instead lower the soil temperature in the pot and affect seedling growth. In summer, the weather is clear and hot, sunlight is intense, and it is also the season when most flowers grow most luxuriantly. At this time, leaf transpiration and soil surface evaporation increase sharply. Only by further increasing watering frequency and amount can the water requirements of flowers be met. On clear days, water at least once a day. During the dog days, the weather is even hotter and drier, and continuous clear, hot and dry weather often occurs, causing intense evaporation from the pot surface and a sharp drop in soil moisture in the pot. This is precisely the season when potted flowers need the most water and consume the most water in the whole year. Drought damage is a serious threat to potted flowers during summer. A slight mistake can cause wilting or even death due to drought. Therefore, on clear days, water once in the morning and once in the evening. In special cases, when the pot soil turns white and dry, timely supplementary watering is also needed. However, potted flowers that are dormant or semi-dormant in summer, such as cyclamen, should have reduced watering frequency and amount. Try to maintain moderate dryness, but do not let them become too dry, because being too dry is also unfavorable for flowers and trees dormant through the summer. Autumn is the turning period from summer into winter. Sunlight weakens, temperatures gradually decline, and potted flowers and trees again enter a slow growth period. At this time, leaf transpiration and soil surface evaporation correspondingly decrease significantly compared with summer, so usually watering once every 2-3 days is enough. Winter is the season with the lowest temperatures of the year. Most potted flowers must be moved indoors to overwinter. The aboveground parts of deciduous flowers and trees wither and drop leaves and are in dormancy. At this time, plant transpiration is negligible, so usually if the pot soil is not too dry, there is no need to water. Water when dry and stop when wet, and being appropriately on the dry side is instead beneficial for most flowers and trees to overwinter. Flowers in greenhouses are usually watered once every 1-2 weeks. Watering at most once every 4-5 days can basically meet their needs. Never water too much or too frequently.
② Observe the weather: Different watering methods should be adopted for different weather, and watering should be carried out in a timely and appropriate amount according to weather change trends. In dry and windy weather, water more and water thoroughly. In cloudy weather with a forecast of rain, stop watering, water less, or delay watering. In continuous rainy weather, not only is watering unnecessary, but accumulated water in the pot should also be removed at any time, and after the rain stops, attention should also be paid to withholding water. In weather with high relative humidity, water less and let the pot soil be on the drier side, while when there has been little rain earlier, relative humidity is low, and no rain is forecast for the future, water more.
(2) Watering by observing the flowers. Watering by observing the flowers means choosing appropriate watering timing and amount according to the moisture preferences of various flowers, their growth and development stage, and their current growth vigor and appearance. In specific operations, attention should be paid to the following issues:
① Judge watering time and amount according to flower species and variety: moisture-loving flowers with high water demand should be watered more; drought-loving flowers with low water demand should be watered less. Generally, herbaceous flowers have tender stems and leaves and need more water; woody flowers have firm stems and need less water. Cacti and other succulent plants should prefer dryness over wetness; bulb and corm flowers should not remain wet or overly wet for long; fleshy-rooted flowers such as peony like dryness and dislike wetness, so they should not be watered much; aquatic flowers like water and fear drought. Broadleaf and many-leaved flowers with large crown diameters should be watered more, while narrow-leaved and small-leaved flowers with small crown diameters should be watered less.
② Judge time and amount of watering according to the growth and development stage of flowers: flowers in a vigorous growth stage need more water and should be watered more; flowers in a slow growth stage need less water and should be watered less. Most flowers need little water at the seedling stage, and during the seedling hardening stage watering should also be appropriately controlled. During the vigorous growth stage, the pot soil should be kept regularly moist. Some herbaceous flowers also need appropriate water control before the flowering stage, and normal watering should resume only when flower bud differentiation stops. When entering the flowering stage, the pot soil should alternate between dry and wet, and after flowering the pot soil should not be too wet. During the seed and fruit maturation stage, the pot soil should be slightly on the dry side. During dormancy, watering frequency and amount should be reduced, and it is enough to keep the soil from becoming excessively dry. Whether potted flowers need watering is often reflected in their external morphology. For example, if new leaves, young leaves, young buds and young flowers wilt, it indicates that the flowers have begun to lack water. The severity of wilting can roughly reflect how much water is needed. Conversely, excessive growth of the plant, thin and tender stems, thin and yellow leaves, and sparse flower buds indicate excessive watering. Sometimes after suffering from wet damage, flowers also show symptoms commonly seen in drought-affected flowers, such as yellow leaves, leaf drop and flower drop. It is necessary to distinguish and decide whether to water. If the plant indeed shows severe wilting symptoms such as drooping leaves and young branches due to drought, it is best not to water immediately. Instead, first move the potted flower to a cool place, water a little, and after the branches and leaves basically return to normal, water thoroughly, and then it can recover vitality. If it is because the pot has had too much water for a long time, promptly move the potted flower to a well-ventilated and shaded place, stop fertilizing, strictly control watering, pay attention to clearing the drainage holes, and carry out deep intertillage and soil loosening in a timely manner to promote water evaporation and improve aeration in the root zone. Spraying a small amount of water mist on the wilted branches and leaves also helps root healing and recovery and maintains water balance in the plant body. If the plant wilting is caused by overly concentrated fertilizer, immediately shade it and water repeatedly to lower the excessively high soil solution concentration, while also raising the bottom of the pot to promote the rapid overflow of excess water through the bottom hole. What needs special attention is that some potted flowers with relatively strong drought preference do not show abnormal external morphology when drought first begins. Once obvious wilting symptoms truly appear, it will inevitably affect the ornamental effect of the plant. Watering again at that time is clearly too late. Therefore, judging whether potted flowers need watering from external morphology is sometimes not completely reliable.
(3) Watering by observing the pot. Potted flowers require special attention to watering by observing the pot. In specific operations, attention should be paid to the following points:
① Observe the size of the flower pot: A small pot holds limited soil and stores less water, and it also has a relatively large surface area, so it loses more water and dries faster than a large pot. Therefore, small pots should be watered more frequently, and the amount each time should be less. However, the amount of water per watering should be slightly more for large pots than for small pots; otherwise, a "waist-cut" water condition easily occurs. If the pot is too small to meet the need, it should be promptly replaced with a larger pot.
② Observe the texture of the flower pot: Commonly used clay pots have a relatively rough texture, and there are countless tiny pores in the pot wall. These pores have strong water seepage and air permeability, and the water lost through these pores every day is also considerable. In contrast, purple clay ceramic pots, glazed porcelain pots and so on have very fine texture and few pores in the pot wall, and their water seepage and air permeability are too poor. Pots with rough texture need to be watered more often, and the amount each time needs to be larger, while when using ceramic pots to grow flowers, watering must absolutely not be too much or too frequent; otherwise, root rot and death are very likely. For old clay pots, because the pores in the pot wall are mostly blocked by mud, watering frequency and amount should also be reduced as appropriate.
③ Observe the soil quality in the pot: Soil with a relatively heavy sandy nature is coarser in texture, has large porosity, drains quickly, has low water-holding capacity, and has weak water retention, and is prone to dryness rather than waterlogging, so watering frequency should be appropriately increased. Heavy clay pot soil is "a mess when wet, a knife when dry." While paying attention to preventing waterlogging, also pay attention to preventing drought. Timely intertillage and soil loosening and breaking up surface compaction of the pot soil can appropriately reduce watering frequency, while the amount each time should be increased as appropriate. Humus soil rich in organic matter has lower evaporation from the pot surface, is loose in texture, and has a large water-holding capacity, so water supply and frequency should be appropriately reduced.
④ Observe the color and weight of the pot soil: When dry, soil color becomes lighter, weight becomes lighter, and hardness increases. Moist soil is the opposite. Therefore, if your pot soil is whitish in color, relatively light in weight, and hard to the touch, it means the pot soil is already dry and more water should be added in a timely manner. If the pot soil still appears dark gray or dark brown, is heavy in weight, and feels soft to the touch, it means the soil is moist and there is temporarily no need to water.
⑤ Listen to the sound of the pot. When you gently tap the flower pot with your finger, if the pot wall produces a crisp and bright sound, it indicates that the pot soil is on the dry side and should be watered. If the pot wall produces a low and dull sound, it indicates that the pot soil is on the wet side and there is temporarily no need to water.
⑥ Observe whether there are abnormal conditions that need to be addressed: For example, when newly potted flowers lack soil moisture, a separation between the pot and the soil often appears. At this time, if a large amount of water is poured directly, it will inevitably cause water to quickly escape along the separation cracks through the bottom hole. In this situation, it is best to first use growing medium to block the cracks around the pot wall, then slowly pour in a small amount of water, and after the pot soil is soaked, water according to the normal method.