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The main conditions of orchids

Even the most unassuming cultures cannot live where conditions of existence contradict their biological characteristics.

What to say about orchids, most of which are so demanding that they can refuse to flower even with decent care. For the maintenance of orchids at home you need to create appropriate conditions, that is, to provide the necessary temperature, light and humidity conditions.

Almost all orchids, with the exception of a small number of variegated species, are grown in culture for the sake of beautiful flowers. Making some orchids bloom regularly is not an easy task even for an experienced grower.

Perhaps this is the main reason for studying how to contain orchids at home - in constant search, experimentation and discovery of the new.

Light orchid content

It has long been known that light is the determining factor in the normal functioning of a plant. It is he who starts the processes of photosynthesis and induces the roots to absorb moisture, the vessels - to direct and redistribute substances in the tissues, the meristem - to divide and form new cells.

Illumination is used to assess the lighting conditions, it is measured in lux (lux) with special devices - lux meters. During the day and depending on the conditions, natural light varies greatly.

For example, on a summer, sunny day in an open area, the illumination is 100000 lux, at the same time in the room near the south window it is already equal to 50000 lux, and on the north window it is only 4000 lux. In the summer, in cloudy weather, when the sky is covered with clouds, the illumination in an open area decreases to 1000 lux.

Retreating from the window into the room, natural light falls very quickly. So, if the total illumination outside the window is taken as 100%, it will be 0,5% at a distance of 50 m, 1% at a distance of 25 m, 1,5% at a distance of 10, and about 2% at a distance of 5m.

The illumination is strongly influenced by a dirtier orientation of the window in the cardinal directions. Plants located on the north window receive approximately 1 / 10 part of the total illumination level of the south window.

Illumination on the windowsill in winter:

  • South window: Sunny - 6000-20000 lux Cloudy - 2000-4000 lux
  • East window: Sunny 2500-4000 lux Cloudy-1000-2500 lux
  • West window: Sunny - 2000-4000 lux Cloudy - 1000-2000 lux
  • North window: Sunny - 1000-2000 lux Cloudy - 300-500 lux

Getting acquainted with the recommendations of how to maintain orchids, try to distinguish between the optimal and the minimum degree of illumination. Usually, recommendations give an optimum degree of illumination and characterize it as “low”, “medium” and “high”.

“Low” illumination lies within 5000 — 15000 lux, “medium” - 15000 — 30000 lux, and “high” - 30000 lux and above. Such illumination is typical for species in their natural growing areas and at optimum temperature stimulates maximum productivity - a good growth of shoots and roots, regular flowering. For example, for phalaenopsis, the optimal illumination is equal to 25000 lux at a temperature of daytime 23 ° С, at night 18 ° С.

But when keeping an orchid at home, one should focus not on the optimal, but on the minimum illumination that is kept in our apartments during 6 and more autumn-winter months during the year.

At the same temperature, the minimum illumination for phalaenopsis is 7500 — 11000 lux. The table shows the minimum illumination that orchids need in these temperature conditions.

Table "Minimum illumination and temperature for some genera of orchids":

RaceMin illumination (lx)Min temperature (° С)


To give2000-750018-20


















































In temperate latitudes during the winter months, the illumination is so low (less than 100 lx in cloudy weather) that on the window sills without artificial illumination the process of photosynthesis in tropical plants almost completely stops.

In winter, the consumption of plastic substances in the process of respiration (which occurs continuously, day and night) takes place against the background of the low efficiency of photosynthetic reactions, which leads to depletion of the plant.

One-sided room lighting, part of which is delayed and reflected by window panes, a sharp drop in illumination when moving away from the window into the interior of the apartment, dependence on the orientation of the windows on the cardinal points — all this makes lighting necessary for almost all orchids grown in rooms.

Most tropical orchids, which are located at some distance from the equator, require small seasonal changes in the length of the light period. During the “artificial” summer, the length of the day for the successful maintenance of orchids should be no less than 14 hours during the maintenance of the house, in the winter - 12 hours, and from April the length of the day should gradually increase again to 14 hours.

The exceptions are equatorial species, which grow in natural areas throughout the year, with 12-hour cycles alternating day and night.

From what hemisphere is the birthplace of orchids, depend on the rhythms of their spine formation, and many residents of the southern hemisphere are forced to give a vegetative growth in the long winter months of temperate latitudes.

They develop "winter" leaves, usually narrower and longer, not adapted to the reflection of the bright spring sun, as a result of orchids located on the southern window, in March — April sunburns may appear on the leaves.

Types of orchid photosynthesis

Photosynthesis is the process of formation of organic substances from carbon dioxide (CO2) and water (H2O) in the light with the help of chlorophyll pigment, which is located in the chloroplasts of plant cells.

In chloroplasts, carbon dioxide and water, with complex interaction with chlorophyll, form oxygen (О2) and glucose (С6Н12Х6), which, then, is converted into starch, fiber, fats and vitamins, is the building material for new cells and organs of the plant.

Orchid, absorbing light energy, turns it into the energy of chemical bonds and accumulates in the form of organic compounds.

When breathing, the reverse process occurs - the decomposition of complex organic compounds into simpler, accumulated organic matter is consumed with the release of the energy necessary for plants to carry out growth processes and many other vital functions. Breathing is carried out both day and night.

Carbon dioxide, which enters the plant during photosynthesis and leaves it during respiration, uses the same “gates” for the passage - the stomata, which are located on the leaves, stalks, peduncles and flowers.

Through the same stomata, plants release oxygen released during photosynthesis, and they also absorb and evaporate excess water. The work of stomata that regulate the supply, conversion and release of carbon dioxide is directly related to the type of orchid photosynthesis.

Currently, orchids have identified several types of photosynthesis: С3, С4, CAM (Crassulacea Acid Metabolism) and С3 — CAM (self-interrupted photosynthesis).

  • In C3 photosynthesis, carbon dioxide enters the plant through open stomata, both during the day and at night.
  • In C4 photosynthesis, the stomata partially cover during the day.

Such photosynthesis is an adaptation of plants for experiencing drought, high temperatures, salinization substrate and lack of carbon dioxide. The special feature of С3-photosynthesis is that the absorption of carbon dioxide occurs in one place of the sheet, and its processing - in another.

So far this type of metabolism has been found in a small number of orchids, but its wider distribution, as well as combining with CAM-photosynthesis (С4 — CAM-photosynthesis) is quite possible.

During the CAM-photosynthesis of the plant, in order to avoid excessive water loss, all stomata is closed during the day, and the absorption and conversion of carbon dioxide into malic acid or malate occurs only at night. Exactly the same type of carbon storage is used by desert plants - cacti and succulents.

CAM photosynthesis has been found in many genera from the subfamily Epidendroideae: Angraecum, Coelogyne, Su rubidium, Oncidium and Yar.

Self-switching С3 — CAM-photosynthesis, apparently, is quite widespread among epiphytic and lithophytic orchids from regions with a clear alternation of dry and wet seasons.

Under favorable climatic conditions (optimum temperature, sufficient illumination), these stomas are open in the daytime, carbon dioxide penetrates the plant during the day, and they function like ordinary plants with С3 photosynthesis.

But as soon as the conditions change dramatically (lack of water, lack of light, strong decrease in night temperatures, excess salt in irrigation water, etc.), the orchid switches to night consumption of carbon dioxide, but CAM-type.

CAM orchids close the stomata during the day to minimize water loss. They breathe and absorb carbon dioxide and water only in the dark, at low temperature and high humidity.

The carbon dioxide absorbed at night is converted into malic acid through a complex of complex chemical reactions. In the light, malic acid moves from the sites of synthesis to the organs of the orchid and is used by the plant as a carbon donor.

Almost all orchids with thick, fleshy leaves are prone to the self-switching C3 - CAM-photosynthesis, in particular this concerns monopodially growing orchidsincluding Phalaenopsis (Phalaenopsis).

Under conditions of high air humidity and good light, plants consume carbon dioxide, resorting to С3 photosynthesis, leaving the stomata open during the day, rapidly increasing biomass and easily blooming.

But once the conditions of orchid maintenance get worse, and you, almost imperceptibly, become the owner of a completely different CAM plant, in which the leaves thin out, shrink and grow more slowly.

Light compensation point of orchids

When the intensity of photosynthesis (the amount of carbon dioxide consumed) and respiration (the amount of carbon dioxide emitted) are equalized, a so-called light compensation point occurs in plants. In the state of the compensation point, the plant enters a phase of forced rest: using as much carbon dioxide as it consumes, it can neither increase biomass nor bloom.

In shade-tolerant orchids, the light compensation point is 1% of total illumination (250 — 300 lux), in light-loving ones — 3 — 5% (800 — 2000 lux). The formation of new cells begins after increasing this level of illumination, and with a lack of light, the plant, on the contrary, is depleted.

In addition to light, light compensation point is highly dependent on temperature. The higher the temperature, the plants breathe more actively, which causes additional energy costs and upsets the balance between production and consumption of carbohydrates during photosynthesis and respiration.

The plant begins to give more than it produces, and compensates for the lack of carbon by taking it from old leaves, shoots and roots. The previously accumulated nutrients are spent only on maintaining their own vital activity, but there is no longer any energy left to develop.

Therefore, it should always be remembered that the high temperature at night to orchids is just as harmful as low light during the day, since it also prevents carbon dioxide from fixing.

An orchid growing at constantly elevated temperatures and low light levels ceases to form peduncles, thus trying to save a portion of the energy expended for breathing. Then, if the situation has not changed, the temperature remains high and breathing still prevails over photosynthesis, shoots and leaves begin to shrink.

As a result, small pseudobulbs and leaves will not be able to ensure the accumulation of sufficient nutrients for the growth of the next year, the shoots will become smaller and smaller every year. Such a negative developmental dynamics can result in the death of the plant.

The maximum productivity of photosynthetic reactions in plant cells of С3 orchids is observed in the temperature range 20 — 35 ° C, at higher temperatures, the intensity of photosynthesis decreases, and at temperatures above 42 ° C, in the organism of an orchid irreversible processes occur, leading to burn or even death.

At daytime temperatures from 13 ° C and below, the intensity of photosynthesis also decreases.

In the floriculture, using Phalaenopsis as an example, they compared the carbon dioxide absorption efficiency at night — at 24 ° С and at 16 — 18 ° С. It turned out that the effectiveness of the second option in 10 times more.

This means that lowering night temperatures is one of the main conditions for increasing green biomass and the formation of peduncles. If it is hot in the room at night (above 24 ° C), the process of formation of new tissues slows down and the plant again takes carbon from its old organs - leaves, stems, peduncles and roots.

When it gets too hot (above 32 ° C) and is dry (humidity drops below 70%), carbon dioxide from the air stops flowing through the stomata, instead, the reverse process takes place - moisture that protects the plant from overheating.

Having given all possible water, the stomata close for a long time, and the photosynthesis of the plant switches from С3 to CAM in order to prevent leaves from fading from excessive evaporation. With a long-term CAM regime, irreversible processes may begin in the leaves of orchids, in which their cells begin to die off gradually.

In winter, the care of the orchid when you keep at home should be given special attention. The grower should make a lot of effort to break this vicious circle - low illumination on the windowsill requires a decrease in temperature, at low temperature the intensity of photosynthesis drops, and a short day reduces the period of the plant’s effective photosynthetic activity.

How to keep an orchid at home: the right light

Additional lighting is used not only to illuminate plants with lamps with a "useful" spectrum, but also to extend the daylight on our window sills. If the plant is located at a distance of more than 1 m from the window, it is necessary to speak no longer of supplementary illumination, but of light-culture. In the depths of the room, the lamps act as the main source of light and are responsible for the full development cycle of orchids.

It is known that only short blue and long red light waves take part in the process of photosynthesis, while waves of green light remain unclaimed. This is due to the characteristics of the pigments, which do not absorb light corresponding to their color.

In other words, chlorophyll looks green because it reflects the green part of the spectrum. At the same time, it absorbs red light (with a wavelength of 640 - 700 nm) and blue light (with a wavelength of 410 - 450 nm). With artificial illumination, blue-spectrum lamps stimulate vegetative growth of plants, and with red they bloom.

For proper illumination of orchids use bicolor lamps with red and blue light sources. The combined EED lamps T8 and T5, in which the ratio of red and blue sources is equal to 8: 1 or 5: 1, have proven themselves well.

However, the light only from the blue and only from the red lamps to the plant is not enough, since a substantial part of the spectral composition of the light in such a backlight is still missing.

Therefore, a combination of red-blue and ordinary white fluorescent lamps with a warm glow (models LB (white light), LD (daylight), LDC (daylight with improved color rendition) with 36 W or a bit more) can be a better solution for an orchid photoculture.

Popular today phytolamps (sodium, mercury-luminescent, metal-halogen) stimulate the growth and blooming of orchids, but they have an unpleasant glow for the eyes, high cost and short service life - only 1 a year.

Try not to use incandescent bulbs and conventional energy-saving lamps, since they have a significant part of the spectrum in the zone of yellow or yellow-green light waves that are not involved in photosynthesis.

For additional lighting it is enough to turn on the 2 lamps once a day - in the morning and in the evening on 1 — 2 hours. For the photoculture, it is necessary to adhere to the usual length of daylight in tropical regions, the duration of the light period can be shortened somewhat in order to save electricity.

The scheme of switching the backlight on and off during a photoculture during a year may look like it is shown in the table. Never forget to turn off the lamps in the dark in order to let the plants breathe normally at night.

When caring for orchids while keeping the house cut watering and lower the temperature in the dark on the windowsill without artificial lighting. The optimal difference between day and night temperatures for Phalaenopsis 2-4 degrees.

Table “Duration of the day for a tropical orchid crop”:

MonthLamp on timeLamp off timeDay length



11 hour. 30 min



12 hour. 00 min



12 hour. 30 min



13 hour. 00 min



14 hour. 00 min



14 hour. 00 min



14 hour. 00 min



13 hour. 00 min



12 hour. 30 min



12 hour. 00 min



11 hour. 30 min



11 hour. 00 min

Temperature mode content of orchids

The intensity of photosynthesis in orchids is associated with metabolism. Moreover, the division of orchids into “warm”, “moderate” and “cold” depends on the optimum of their photosynthetic activity.

The optimal fixation of carbon dioxide for most epiphytic and lithophytic tropical orchids with self-switching С3 — CAM photosynthesis occurs at temperatures 15 — 24 ° С. Under the condition of high humidity, their stomata are open both day and night, and the leaves work as С3-photosynthesis.

But to absorb carbon dioxide at high night temperatures (more than 25 ° С) leaves with С3 photosynthesis are practically incapable. However, when the night temperature rises, the air becomes drier, to prevent excessive evaporation of moisture, the stomata close and after some time (within a few days) the plant switches to CAM-photosynthesis.

After the humidity and temperature are optimized, the orchid will adjust again and in a few weeks will return to С3 — photosynthesis.

For thermophilic orchids with self-switching С3 — CAM photosynthesis, for example, for Phalaenopsis (Phalaenopsis), Cattley (Cattleya)island species from genera Dendrobium (Dendrobium) it is desirable to maintain an even temperature at the level of 16 — 24 ° С during the year with a slight difference in day and night temperatures of 2 — 4 ° С.

Table "Temperature regimes for orchid cultivation":




(° C)

Day (° C)

Night (° C)

Day (° C)

Night (° C)
Geply day + warm night ("warm")






1'ther day + cool night ("moderately warm")






Cool day + cold night (“moderately cold”)






Hungry day + cold night ("cold")






At the other extreme, there are alpine species, for which diffuse illumination and cool conditions with temperatures of 8 — 16 ° С are required during the year. However, the main group consists of orchids growing in a monsoon climate, for which temperature regimes must necessarily include both daily and seasonal variations in 6 — 8 ° С.

To a lesser extent, this concerns equatorial species with С3-photosynthesis, in natural habitats growing under the canopy of rainforest, to a greater extent - CAM-epiphytes from lowland forests.

The higher the temperature of the orchid content, the more intense the respiratory process. Night temperature decreases the respiratory activity and more plastic substances enter the growing organs of the orchid. Thus, the reduction of nighttime temperatures in comparison with daytime temperatures provides the plant with more intensive growth.

However, the difference between day and night temperatures at 10 ° C causes excessive evaporation of moisture through the stomata of С3 orchids. As a result, for example, in flowering Cymbidia (Cymbidium), on the underside of the leaves and on the peduncles droplets of a viscous liquid may protrude.

To normalize the metabolism of such orchids, it is necessary to adjust the temperature regimes so that the difference between day and night temperatures does not exceed the critical threshold in 10 ° C and does not cause excessive evaporation of moisture.

Orchid care at home during the resting period

During the year, many epiphytic orchids have clearly pronounced rhythms of spine formation, during which periods of active growth alternate with periods of rest. The fact that the orchid is at rest is indicated by signs such as cessation of growth or even death of the roots, dropping of leaves, wrinkling of pseudobulb.

There are biological and forced periods of rest. Biological dormancy comes no matter what the surrounding conditions; it is caused by annual climatic changes in the homeland of the plants to which they adapted during a long evolution.

External manifestations of biological dormancy can be the complete death of leaves and roots, such as Pleione (Pleione)However, at this time, inside the vegetative-generative buds, there are processes hidden from our eyes - the formation of buds of leaves, roots, and even flowers.

Forced rest is observed in orchids, adapting to the unfavorable conditions of our apartments. Most orchids in the northern hemisphere, grown without artificial illumination, are forced to rest in winter, when the light level and the duration of the light period are reduced to a minimum.

Orchids can also go into a state of forced rest when the temperature rises and at the same time decreases the humidity. But much more often, rest is stimulated by a lack of light in combination with low humidity.

Experienced orchid growers know that when there is a lack of light so that the plant does not disturb the balance of accumulation and consumption of nutrients, the temperature must be artificially lowered. At the same time, at a low temperature the substrate dries out more slowly.

Therefore, while caring for orchids when kept at home, in winter, reduce watering: the water received at this time should only compensate for the moisture that the plant spends on evaporation through the stomata.

Relative humidity for orchids

In crop production, four ranges of relative humidity are distinguished.

Table "Indicators of relative humidity":

Very high




80% and more




Most rainforest orchids prefer high relative air humidity, which affects the stoma opening mode. The greater the humidity, the wider the stomata open, and the more carbon dioxide they absorb from the air.

In the С3-photosynthesis mode, the stomata of orchids work most effectively at high relative humidity (70 — 100%). However, during periods of rest, humidity can drop to 50 — 60% without harm to plants.

Even Phalaenopsis (Phalaenopsis)Orchid, which does not have special “reservoirs” for storing liquid, is relatively unpretentious to moisture: it grows well with relative humidity 70-75%.

One of the signs of insufficient air humidity in some orchids is the formation of a young leaf harvested in an accordion, with small folds forming across the leaf blade.

In dry air folded leaves appear in Tselogine (Coelogyne), Cumbria (Cambria), Odontoglossums (Odontoglossum) and many other genera of orchids with thin leaf blades.

Other signs also indicate insufficient air humidity. Have Cattley (Cattleya)For example, shoots become ribbed, Venus slippers thinner and brighten the leaves, Phalaenopsis (Phalaenopsis) the growing tips of the roots die off, and the lower leaves gradually fall off, this continues until the entire 2 — 3 leaf remains on the shoot.

You can create a high level of humidity for orchid care when kept at home using a variety of tricks.

For example, in a particularly hot period, you can wipe plants several times a day with a damp cloth, cover them with wet gauze, spray the leaves and walls of the room greenhouse with water from a spray bottle, and hold pallets of water on window sills.

However, these measures are not effective enough. Sooner or later, moisture control may weaken, and then actively growing shoots of plants will suffer greatly.

It is better to maintain the necessary humidity with the help of special fogging nozzles and household air humidifiers, which can saturate it with moisture using warm or cold steam, as well as using ultrasound.

The most modern models created for use in residential premises are called climate complexes, they combine the functions of humidification and air purification.

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