Abundant and moderate watering

The problem of improper watering is one of the most common misfortunes faced by flower growers, especially beginners. The bad thing is that different plants have different sensitivity to excessive or insufficient watering. The harm caused to the plant from systematic waterlogging is primarily associated with a violation of the oxygen regime in the root system. Oxygen access to plant roots is hindered, causing hypoxia, or completely stopped, causing anoxia. 

As we remember from the course of botany, plant roots absorb the oxygen necessary to breathe the plant directly from the soil. And this is possible only if the soil is sufficiently loose, structured, consisting of lumps, the space between which is filled with oxygen. According to scientists, for the growth and development of various plants, a certain minimum of oxygen in the soil is required - above 10%, and the lower permissible limit is 5%.

Root respiration is accompanied by oxygen uptake and SO2 release. The main material for plant respiration is glucose. The glucose molecule is split into two triose molecules, which are subsequently oxidized to pyruvic acid, and then completely oxidized to SO2 and N2O in the cycle of tricarboxylic acids - this is aerobic respiration.

If the plant is watered too often, when the earth does not have time to dry out, then the space between the grains of land is filled with water. Anaerobic processes develop in the soil: pyruvic acid is converted into alcohol and lactic acid (fermentation). Carbon dioxide, methane, organic acids and other compounds accumulate, most of which act poisonously on the root system of plants, these are the so-called marsh toxins. In root cells, electron transport and oxidative phosphorylation (a step in cellular respiration leading to energy in the form of ATP) cease. Tricarboxylic acid cycle reactions do not occur (Krebs cycle) - after all, this is an aerobic process, and its result is free hydrogen, which is involved in tissue respiration and ATP synthesis. ATP production decreases, and with such a lack of energy, metabolic processes slow down. There is a deterioration in the assimilation of ions from the soil, a gradual death of the roots, and in the aboveground parts of plants there is a lack of nutrients, primarily chlorosis, growth is delayed.

More precisely, many plants are able to tolerate a short-term bay, because in nature there are often torrential rains, rivers overflow, flooding the banks. But there is one very important point - these waters are renewing (riverine groundwater is constantly in motion) and they are saturated with oxygen! Stagnant waters are dangerous - there is almost no oxygen in them. Please note: single species of plants can grow on swamps, only those who are able to tolerate root anaerobiosis: fluffy birch, some species of willow, alder buckthorn.

Plant water demand

Among the indoor plants that are collected on our windowsills from different parts of the world, different families, genera and species are committed, their attitude to soil moisture and soil structure is different. Plants capable of synthesizing ATP due to anaerobic metabolism of units during waterlogging (prolonged drying of the substrate), and even the fittest ones usually withstand no more than 3-5 days of strong moisturization. But the trouble is that in addition to the root system of plants, useful soil microorganisms need oxygen, which is sorely lacking in waterlogged soil. Under anaerobic conditions, they die, but pathogenic microflora begins to multiply intensively - pathogens of many plant diseases, root and stem rot appear, the plant dies not from anoxia and poisonous gases in the soil, but from bacterial and fungal rots.

In some cases, when flower growers understand that they have unnecessarily watered the plant, and it is depressed due to the error of watering, they manage to correct the situation - loosen the soil or transplant flowers, but the process has already started and moist brown spots of necrotic tissues appear on the plants. In such cases, the usual measures to resuscitate flooded plants are not enough, treatment with fungicides capable of killing pathogenic microflora is required.

But back to the ratio of various plants to the aquatic environment and survival in conditions of high humidity. To do this, we turn to the well-known classification of plants into ecological groups in relation to various environmental factors. In addition to the habitat, different groups of plants have or do not have aerenchyma - air-bearing tissue, which has very large intercellular spaces filled with air. Moreover, intercellulars and air cavities in the roots, stems and petioles of leaves communicate with each other, and not only serve as a reservoir for oxygen, but also help tissues that find themselves in conditions of lack of oxygen not to suffer from hypoxia.

• Hydatophytes are aquatic plants that are completely immersed in water and absorb nutrients from the entire surface (aquarium plants). These plants die in a matter of minutes if they are taken out of the water - they have no stomata, no cuticles, they are not adapted for life outside the water. But they have very well developed aerenchyma.
• Hydrophytes - plants partially submerged in water, live along the banks of reservoirs, in swamps (arrowhead, lotus). But this group of plants has better conductive and mechanical tissues than hydatophytes. Aerenchyma is also well expressed. The epidermis has stomata, and the intensity of transpiration (evaporation by a plant of water) is very high.
• Hygrophytes are plants from places with high air humidity. Among them, two categories are distinguished: shadow and light. Shadow hygrophytes are plants of the lower tiers of raw forests (circe). Light hygrophytes grow in open places, but also on constantly moist soils and in moist air - the most famous representatives are rice, sundew, thyroid, neptunia garden.
• Hygrophytes are moisture-loving plants, they have low drought resistance. They have fairly large thin leaves, and a few stomata on both sides of the leaf and they are always open. The transpiration process is poorly regulated. Drying for such plants is destructive. The plants feature dense but underbranched roots with very limited sucking roots. Aerenchyma in some hygrophytes is quite developed, in others it develops vigorously in conditions of increased soil moisture.

• Mesophytes are plants that grow in habitats with sufficient, but non-redundant moisture, they are able to tolerate minor soil drying and dry air for a short time. The stomata on the leaves are located on the underside, and they have a good mechanism for regulating stomatal transpiration. These plants are the most convenient for flower growers, quite plastic, they adapt most easily to soil and air humidity. A well-developed root system with a dense network of sucking roots is typical for them. In normal condition, mesophyte plants do not have aerenchyma. But when it gets into conditions of high humidity, in conditions of hypoxia, the formation of ethylene sharply increases in the roots of mesophytes, which triggers such a phenomenon as apoptosis of cells.

• Xerophytes are plants that grow in places with insufficient moisture (deserts, steppes, sand dunes and hard-leaved evergreen forests), for us they are cacti and succulents. They have devices that allow you to extract water when it is not enough, limit the evaporation of water or store it during a drought. These plants lack aerenchyma and are unable to develop it. In conditions of waterlogging, these plants die very quickly.

Among common houseplants, the vast majority are mesophytes. The division according to this classification is somewhat conditional. Many plants behave not as one hundred percent mesophytes, but as mesohygrophytes (tend to regulate their water metabolism as hygrophytes) or as mesoxerophytes (more tend to drought-resistant forms) - such plasticity allows plants to survive in a variety of unfavorable conditions.

Among houseplants, hygrophytes and mesohygrophytes are from tropical forests. Hygrophytes, and there are not many of them are tropical grasses, for example, selaginella, soleirolia, plaunas (some are grown as ornamental), phyttonias, balsamines, and some species of begonias. Those that grow on the forest floor and during prolonged rains are "knee-deep" in the water. Mesohygrophytes: tradescantia (and other commercial), ferns, philodendrons, some types of palm trees. But not all plants living in the lower tier of the rain forest are hygrophytes or mesohygrophytes, quite a lot of epiphytes grow there (bromeliads and orchids), their roots never end up in puddles of water, because they cling to tree trunks or grow on forks of fallen branches, they catch water or funnels of leaves (bromeliad), or protruding broadly to the sides fleshy roots covered with root hairs (orchids).

It must be said that the demand for substrate moisture is highly variable within a single family. Take, for example, orchids - a vast variety of species, including most mesophytes, but there are also hygrophytes, for example, Losnyak Lezel, in Russia it is found in the forest and forest-steppe zones of the European part and in Western Siberia. It lives on sphagnum swamps, peat rafting, marshy meadows, swampy shores of lakes, it grows among reeds like marsh grass. Or, for example, the ficus family. Their attitude to water is also different: ficus benjamin and rubber-bearing pronounced mesophytes, do not tolerate waterlogging, tolerate drying well. But ficus pumila - hygrophyte, dies as soon as the soil dries completely and grows perfectly with regular heavy watering.

Outwardly, it is possible to distinguish moisture-loving plants that do not tolerate drying out only in general terms: the main difference is thin, not leathery leaves, for example, like hibiscus, fittonia. When the substrate dries up, their leaves quickly lose their turgor and droop deplorably. But it cannot be said that they are resistant to overflow, let's say they need a more moisture-intensive substrate. But, as I mentioned at the beginning of the article, they are not able to put up with too wet soil, since their roots will inevitably be in a state of hypoxia. I.e. we can only talk about the increased need for water, but not about immunity to the bays.

What is abundant watering

We move on to what is considered abundant watering, moderate and what will be considered an overflow. As you understand, the correct amount of water for irrigation cannot be measured with tablespoons or liters, just as the frequency of irrigation cannot be measured in days. The only indicator that dictates the pace and volume of watering is the state of the substrate.

And it, in turn, develops and depends on many factors, here are the main ones:

• loose and structured substrate,
• degree of filling with its roots,
• soil humidity,
• presence of drainage holes on the bottom of the pot,
• ambient air temperature and humidity.

The looser and lighter the substrate, the faster it dries. For example, sheet earth or peat, twice (about!) Dries up faster than clay or garden (with a large dose of sand, clay and humus). The soil in the pot dries significantly faster if almost the entire space is filled with roots, and significantly longer if the pot is large, a lot of free land. Drainage holes at the bottom of the pot also play a role - excess water flows into them. But if the soil is heavy, clay, then no drainage holes will accelerate its drying! The higher the room temperature and the lower the humidity, the faster the soil dries in the pots.

The two dracens (left and center) look exactly the same, as if the same plant, but no, just the picture of the bay is too typical. And on the right yucca, not to distinguish from dracen - from the words of the hostess: "the crown is soft, the ground is moist, but there was no bay!" Unfortunately, it only seems that there were no bays, in fact, systematic abundant watering leads to such a state.

Thus, it turns out that two identical plants planted, say, with Masha and Vanya in pots of the same diameter need a different irrigation regime, because, for example, Masha bought peat soil, and Vanya accumulated it in her garden. Masha has a room temperature of + 22 degrees and humidity of 50%, and Vanya has + 26 at a humidity of 20%. And you can only check if it's time to water by touching the ground. Not slightly picking the upper 2 cm with your finger, but plunging your finger into the ground. And depending on how wet the ground inside the pot is, water or wait.

Abundant watering is considered such when the soil for the next watering manages to dry out in the upper third of the pot. It is to dry completely - dry at the top, slightly wet closer to the middle of the pot. Not damp, not wet, but not dry either. Of course, it is difficult to explain these feelings, otherwise everything would be clear to everyone, and it is unlikely that so many bays happened.

Moderate watering - when the ground has time to dry about half the pot or in the upper 2/3 of the pot. Of course, the length of the finger may not be enough to touch the soil so deeply, and it is not necessary. If the pot is deep, large, then I do this: in the morning I check (touch) the ground at the top of the pot. If it's still wet, I don't water, I wait until the evening. If it's dry in the evening, I water it in the morning, if not already, I check it again in the morning. I.e. I water not when it dries in the upper part of the pot, but after waiting another 6-8 hours.

Limited watering is when watering is carried out only after complete drying of the earth in a pot, and then not immediately, but after 2-3 days. I.e. for a while the plant must stand with dry roots. At the top of the pot, the ground may already be dry to dust, but at the bottom of the pot it is somewhat wetter. If the plant stands without watering longer, then the whole earth in the pot dries up into dust. The pot seems almost weightless. Why do I say "to dust," because such a dry ground is only to touch - it crumbles like dust, and dust particles fly into the air. If the whole soil in the pot dries up in such a state, then only xerophytes (cacti and succulents) can withstand this. In other plants, the roots dry up and die off.

When keeping plants in rooms, the most common recommendation for watering: abundant in spring in summer, moderate in winter. This applies only to mesophytes, the most common colors in the house: ficuses, crotons, ivory, diffenbachia, aglaonem, palm trees, cissuses, nephrolepises, schefflers, hoyas, etc. I.e. during the growing season (growth), the next watering after the top layer of the earth dries, about 1/3 of the height of the pot. In winter, watering is more moderate for two reasons: in winter, often the temperature is several degrees lower than in summer, and in winter, with a lack of light, plants do not grow, or grow very slowly, i.e. energy consumption is much less.

Danger of waterlogging

Oddly enough, the watering regime is more stable in winter than at any other time. This is due to the fact that in the heating season the temperature in the apartment usually fluctuates no more than 2-3 degrees. Of course, if you have old wooden frames that need to be plugged, glued or a private house where heating can be reduced or added, then the temperature drops are quite significant. But most people now have plastic windows, reliable front doors with insulation, and the temperature in the apartment varies little depending on the weather. I specially measured the temperature in the apartment from November to February several times a week, I have it stable 26-27 degrees, and only when there was a strong wind through the windows, the wind found its way into the ceilings, and the temperature dropped to 24 degrees. Alas, the humidity is no more than 20%.

But in those periods when the heating is turned off, the microclimate in the apartment changes radically - it depends on the weather much more. Firstly, air humidity increases - up to 50% on average, and on rainy days in autumn and summer up to 70%. Secondly, the difference between night and day temperatures increases. During the day it can be 26, and at night 22. We ventilate in the warm season much more often.

The most dangerous time for flowers in terms of watering is at the end of summer and autumn, before the heating season, i.e. the time when the difference in daily temperatures is greatest. Here, drying the ground in a pot directly depends on the weather. And the weather is unpredictable. One week is the heat, we water abundantly, and here the rains charge. It seems to be warm, but with a humidity of 70-80%, the ground in pots dries for a very long time. At this time, the only way not to pour is to check the ground before watering with a finger, and not counting the days by eye.

Also dangerous are the opening and closing (so to speak) of the growing season. Simply put, the beginning of growth is a stormy start of young growth and a sharp slowdown in growth with a reduction in daylight hours in the fall. In the first case, the plants vigorously increase the leaf mass - the evaporating surface increases. Some growers, for joy, try to drink more plants, sometimes overdo it. In autumn, plant growth also suddenly slows down, plus it gets colder, it would be necessary to water less, but by inertia we can continue to water in the same mode.

Thus, I would like to advise florists to think, remember and note such dangerous moments for themselves. You know your house better, whether it is warm or cold, blowing through windows or not, loose ground in pots or not, whether there is a lot of drainage at the bottom of the pot or not at all, etc. moments. Notice the changes in the weather - everything related to cooling and rains should alert.

Another dangerous moment in watering is associated with drying. A very common situation is when the plant turns out to be very dry and they try to immediately drink it abundantly. And this is wrong. After severe drying of the earth, part of the roots dries up and dies. I.e. the suction surface of the roots decreases, sometimes very strongly, and here we are with abundant irrigation, which has nothing to suck in - as a result, the remaining roots rot. This is the same as trying to feed a starving patient at once a lot and abundantly, and he has indigestion.

Reanimation of flooded plants

Watering houseplants