Is an orchid a light-loving or shade-loving plant: how much sun does a flower need at home and what are the consequences of its lack? Selo.Guru

Orchid photosynthesis

The ground part of the orchid (leaves, stem, pseudobulbs, etc.) catch sunlight.

With the help of chlorophyll, they convert it into the energy necessary for plant development, which contributes to the creation of glucose and other organic compounds.

This process is called photosynthesis .

Photosynthesis can only occur under sufficient light conditions.

Insufficient lighting leads to the formation of a smaller amount of glucose, which is insufficient for the normal growth and development of the orchid.

In turn, excessive lighting disrupts the process of glucose formation, leading to leaf burns.

For plants, the intensity and duration of the light falling on them is important.

As the amount of light hitting the leaf increases, the rate of photosynthesis also increases proportionally.

At some point, the plant stops responding to additional lighting, as if becoming saturated.

Each type of orchid has adapted to certain lighting conditions during evolution.

Errors and their consequences

As mentioned above, orchids should avoid direct sunlight . The consequences of prolonged exposure to direct sun are thermal burns of leaves. In particularly severe cases, a characteristic dark spot may form on the leaves. This sheet must be deleted.

IMPORTANT : Another sign of too much sun is the pigmentation of the leaves, which ranges from pink to purple, often cherry. It's not as bad as burns. This pigment tan does not pose a problem for the plant. But still, it is better to avoid pigmentation.

With a lack of light, the flowers begin to hurt . A sure sign of this are narrow, pale, elongated upper leaves, also inclined towards the light source. Another sign is that the plant has stopped growing. This means it's time to turn on additional lighting.

Types of photosynthesis in orchids

Currently, several types of photosynthesis have been identified in orchids:

C3 photosynthesis;
C4 photosynthesis;
CAM (Crassulacea Acid Metabolism);
C3-SAM (self-switching photosynthesis).

C3 photosynthesis

During C3 photosynthesis, carbon dioxide enters the plant through open stomata, both during the day and at night.

The peculiarity of C3 photosynthesis is that the absorption of carbon dioxide occurs in one place of the leaf, and its processing in another.

C4 photosynthesis

During C4 photosynthesis, the stomata are partially covered during the day. Such photosynthesis is an adaptation of plants to survive drought, high temperatures, salinity of the substrate and lack of carbon dioxide.

CAM photosynthesis

During CAM photosynthesis , plants close all stomata during the day to avoid excessive water loss, and the absorption and transformation of carbon dioxide occurs only at night.

The same type of carbon storage is used by desert plants - cacti and succulents.

Self-switching C3—CAM photosynthesis

Self-switching C3-CAM photosynthesis is quite widespread among epiphytic and lithophytic orchids from regions with a clear alternation of dry and wet seasons.

Under favorable climatic conditions (optimal temperature, sufficient light), the stomata of these orchids are open during the day, carbon dioxide enters the plant during the day, and they function like ordinary plants with C3 photosynthesis.

As soon as the conditions change dramatically (lack of water, lack of light, a strong decrease in night temperatures, excess salts in irrigation water, etc.), the orchid switches to night-time consumption of carbon dioxide according to the CAM type.

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

Almost all orchids with thick, fleshy leaves are prone to self-switching C3 - CAM photosynthesis , this is especially true for monopodially growing orchids, including Phalaenopsis.

In conditions of high air humidity and good light, plants consume carbon dioxide, resorting to C3 photosynthesis, leaving stomata open during the day, quickly increase biomass and bloom easily .

As soon as the conditions for keeping orchids deteriorate, it becomes a plant ITSELF, whose leaves thin out, become smaller and grow more slowly .

Light compensation point

When the intensity of photosynthesis (the amount of carbon dioxide consumed) and respiration (the amount of carbon dioxide released) are equalized, the so-called light compensation point .

In shade-tolerant orchids, the light compensation point is 1% of total illumination (250-300 lux), in light-loving orchids - 3-5% (800-2000 lux).

The formation of new cells begins after increasing this light level. With a lack of light, the plant becomes depleted.

Three states of the orchid can be distinguished :

Being at the compensation point - nothing happens.

Being in a state ABOVE the compensation point - the orchid begins to grow roots, leaves, etc.

Being in a state BELOW the compensation point - the leaves and roots dry out, and as a result the plant dies.

In addition to illumination, the light compensation point is strongly dependent on temperature.

The higher the temperature , the more actively plants respire, which causes additional energy costs and upsets the balance between the production and consumption of carbohydrates during photosynthesis and respiration.

The orchid begins to give back more than it produces, and compensates for the lack of carbon by taking it from old leaves, shoots and roots.

Previously accumulated nutrients are spent only on maintaining one’s own vital functions, and there is no energy left for development.

IMPORTANT! High temperatures at night are harmful to orchids, as is low light during the day, since they prevent the fixation of carbon dioxide.

An orchid growing at constantly elevated temperatures and low light levels stops forming flower stalks, thus trying to save some of the energy spent on breathing.

If the situation has not changed, the temperature remains high and respiration still prevails over photosynthesis, shoots and leaves begin to shrink .

As a result, small pseudobulbs and leaves will not be able to accumulate sufficient nutrients for next year's growth.

smaller and smaller every year .

Such negative development dynamics can result in the death of the plant.

The maximum productivity of photosynthetic reactions in plant cells of C3 orchids is observed in the temperature range of 20–35 °C.

At higher temperatures , the intensity of photosynthesis decreases, and at temperatures above 42 ° C, irreversible processes occur in the orchid’s body, leading to burns or even death.

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

A decrease in night temperatures is one of the main conditions for the growth of green biomass and the formation of flower stalks.

If the room is hot 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 becomes too hot ( above 32 °C ) and dry (humidity drops below 70%), carbon dioxide from the air stops flowing into the leaves through the stomata.

Instead, the reverse process occurs through them - the release of moisture, which protects the plant from overheating.

Having given up all possible water, the stomata close for a long time, and the plant's photosynthesis switches from C3 to CAM to prevent leaf wilting from excessive evaporation.

With prolonged CAM mode, irreversible processes can begin in orchid leaves, during which their cells begin to gradually die.

In winter, special attention should be paid to caring for orchids when kept at home.

Low light on the windowsill requires lowering the temperature.

At low temperatures , the intensity of photosynthesis decreases, and a short day reduces the period of already ineffective photosynthetic activity of the plant.

How to find out the requirements of an orchid for light?

How to find out whether an orchid requires light, especially if its name or origin is unknown? The plant itself can help here.

Species with hard, leathery, thickened leaves require a lot of light, and if the leaf has a cylindrical cross-section, then perhaps the maximum amount.

A typical example is the genus Vanda. Vandas are very sun-loving, but one of them, Vanda teres, which has cylindrical leaves, is so demanding of light that at the latitude of Moscow it does not bloom every year, but only after a very hot and sunny summer.

Oncidium splendidum, an orchid from Mexico with hard sword-shaped leaves and a small flat bulb, also grows in open areas in direct sun.

Cattleyas and dendrobiums need a little less light

Orchids with bulbs and thin leaves need even less light . These include (as the need for light decreases): catasetums, lycastes, coelogines, calanthus.

Plants with leathery, soft and wide leaves without bulbs and soft-leaved alpine species with bulbs require even less light , these are phalaenopsis, miltonia, odontoglossum.

Orchids with soft, delicate leaves and thin stems - anectochilus, makodes - have the least needs

Appearances can sometimes be deceiving . If you expose catasetum and calanthus, which are similar in appearance, to direct sun, then the former will only benefit from this, and the leaves of the calanthus will quickly burn.

The rosettes of Paphiopedilums, which in appearance are usually placed in the shade, actually require slightly less light than Cattleyas.

The color and structure of orchids is a good indicator of the correctness of the chosen lighting conditions.

Like indicator paper, the color of their leaves changes depending on light conditions.

In a healthy orchid they are bright green. If the leaves darken , the plant clearly does not have enough light; if they turn yellow or take on a reddish tint, there is too much light.

Rule 8: comply with air humidity standards

And one more requirement for the orchid’s vagaries is air humidity. In rule No. 3 it was already mentioned that this plant does not like dry air, due to which it may stop developing or, alternatively, both the flowers and unopened buds of the orchid may dry out.

The optimal air humidity for orchids is 60% and above. This can be achieved by placing a saucer of water near the flower or, in drier times, by direct spraying. The latter method is especially good during the heating season, when it is warm outside, but the radiators continue to drive heat, and the house turns out to be a little hot.

Lighting needs of orchids

Illumination is used to assess lighting conditions; it is measured in lux (lx) with special devices - lux meters .

During the day and depending on conditions, natural light varies greatly.

The optimal level for orchids varies from species to species, but generally ranges from 10,000 to 30,000 lux.

All orchids can be divided into three groups according to their need for light:

Light-loving species. Requires plenty of sunlight. These include some species: vandas, oncidiums, dendrobiums and a number of others. Optimal illumination is 30 thousand lux.

Requiring moderate lighting . This includes most orchids suitable for indoor conditions. Illumination range 15-30 thousand lux.

Shade-loving orchids , requiring from 5 to 15 thousand lux for normal development. This group includes phalaenopsis, slippers, anectochilus, gemaria and others.

At home, many orchids are content with much smaller sizes.

A houseplant, even one placed right next to a window, receives less than half the light that it would receive in an open place.

The exception is those hours when the orchid “bathes” in the direct rays of the sun. This should not be forgotten when choosing orchids for your collection.

Lack of light not only weakens the plant, preventing it from developing to its full potential, but also negatively affects flowering.

Therefore, winter shoots of cattleyas usually do not bloom, and in Oncidium splendidum, which blooms in winter, the peduncle often stops and dies.

Use of fluorescent lamps

You can increase daylight hours by using additional lighting in the morning and evening hours. Fluorescent lamps are perfect for growing orchids .

The more lamps, the farther the flowers should be from them. Additional light sources may not be needed if the windows are located to the south and the flower pot is not blocked by trees and nearby houses.

You can learn more about the basic rules for caring for a flower, as well as the proper organization of lighting and types of lamps here.

Length of daylight

The intensity of sunlight and the length of daylight hours play a key role in the proper development of orchids and their ability to bloom regularly.

The length of daylight in nature regulates the flowering of some types of orchids. In culture, increasing daylight hours can partially compensate for the lack of light.

In tropical climates, the length of daylight “effective for plant development” (throughout the year) is about 12 hours.

In the European summer, daylight lasts about 16 hours, and in the European winter - about 8 hours.

The intensity of lighting depends on the time of year, the location of the windows in the apartment and the distance of the plants from the window.

In our latitudes, the intensity of outdoor lighting in summer reaches 50,000-100,000 lux, in autumn it does not exceed 30,000 lux, and in winter it is at a level of about 5,000 lux.

A significant role in the distribution of lighting intensity as one moves away from the window is played by the presence of tall trees near the windows of neighboring houses, as well as the location of the populated area (lowland, hill, etc.).

It is impossible to give any specific illumination values for windows of one orientation or another. It all depends on the floor, presence of trees, etc.

The amount of light on the south window of the first floor, completely obscured by the dense greenery of trees and bushes, may be less than on the north window of an apartment on the twentieth floor.

Blooming

Among the shade-loving plants there are many beautiful flowering ones. So you have the opportunity to decorate both northern and foliage-shaded windows with luxurious flowers. It is only necessary to create optimal conditions for plants for lush flowering and active growth.

Spathiphyllum

Spathiphyllum is a beautiful, shade-tolerant indoor flower loved by many gardeners. It feels great on a north-facing window, where its leaves acquire a rich green hue and an elongated shape. Likes frequent spraying and a shower once a month.

Gardenia

Gardenia is a real find for lovers of flowering indoor plants. With good humidity and comfortable temperature (from +16 to 24ºC), this beauty will delight you with its luxurious flowers. Just don’t forget to remove wilted buds in a timely manner.

Saintpaulia

Saintpaulia (Usambara violet) is one of the most common flowering indoor herbaceous plants. It develops well and blooms beautifully in partial shade, with sufficient humidity and comfortable temperatures (from +20 to +24°C).

Vriesia

Vriesia is an unusually beautiful indoor flower, memorable for its bright arrow. However, when growing it, you need to monitor the air temperature (not lower than +18 and not higher than +27 ° C) and the presence of water in its outlet.

Anthurium

Anthurium is a rather capricious, but very beautiful flower, many types of which are intended only for heated greenhouses. When working with the plant, you need to be as careful as possible, as it contains substances that irritate the mucous membrane.

Begonia

Begonia is one of the most beautiful shade-loving plants, whose beautiful large bright flowers decorate any interior in summer and winter. There are about 2000 species of decorative deciduous and decorative flowering begonias. And they all prefer partial shade and moderate watering.

Clivia

Shade-loving clivia pleases gardeners with unusual umbrella-shaped inflorescences located on high peduncles. However, for abundant flowering it needs good watering, light partial shade and fertile soil.

Calathea Crocata

This representative of the arrowroot family is grown for its beautiful leaves of unusual colors: speckled, dashed, dark and light green. Calathea Crocata does not tolerate temperature fluctuations and dry air. Grows well in a closed flower window.

Miltonia

For its lovely flowers, wide open and pansy-like, the miltonia orchid is called “pansy”. Loves partial shade and good humidity. Afraid of drafts. A sign of the correct location of the plant is the pinkish tint of its leaves.

Streptocarpus

Streptocarpus, with its delicate, bell-like flowers, is a real boon for gardeners. It is unpretentious in care, tolerates partial shade, blooms magnificently and for a long time (up to six months) and is easily propagated by any of its parts.

Azalea

Azalea (rhododendron) is rightfully recognized as one of the most beautiful and vibrant flowering indoor plants. In conditions of high air humidity, with regular spraying and observing the temperature regime (from +12 to +20 °C), it will delight you with a luxurious cap of amazing flowers in the winter cold.

Angrekum

Angrecum, like all orchids, is a very delicate and whimsical tropical flower. But it grows well with plenty of moisture and regular spraying with soft, warm water in light partial shade or with sufficient artificial light.

Arrangement of orchids in the apartment

Orchids must be placed in an apartment strictly in accordance with their light requirements.

If an orchid grows in nature in an open area, then its place in the house should be chosen in the south, southwest, southeast.

If in nature an orchid grows in partial shade, then at home it should grow on eastern or very light northern windows.

The ideal place for most orchids is EAST and WEST windows, as there is good lighting in winter and less scorching sun in summer.

Direct sun from the eastern side occurs in the morning, usually until 12:00-13:00. During this period, it is not yet very “hot”; as a rule, there is no need to protect orchids from burning.

On the western side, direct sun shines in the late afternoon, usually starting at 3:00 p.m.

The main difficulty is that the intensity of sunlight increases greatly (compared to the eastern window). This leads to massive burning of the leaves of many types of orchids.

Recommended! During the hot summer period, shade orchids in the afternoon on western windows.

South windows are considered the most productive in winter and the most dangerous in summer.

The intensity of sunlight here throughout the year is the highest possible in an apartment.

In summer, direct sunlight shines during most of the daylight hours (almost from morning to evening).

Therefore, it is recommended to remove tender plants from the windowsill during this time, hiding them behind tulle curtains.

Or grow there types of orchids that can easily tolerate sunlight intensity of 50,000 lux or more.

The main problem is not only leaf burns, but regular OVERHEATING of orchids, since the process of water circulation inside the plant begins in the root system and ends with the evaporation of moisture through the pores of the leaves.

The hotter the orchid’s environment, the faster the process of moisture evaporation from the surface of the leaves occurs, the slower (until it completely stops) is the process of replenishing it through the roots.

Conventionally, in 1 hour, 20% of the moisture evaporates from the surface of the leaf, and about 5% is absorbed through the roots (in overheated conditions).

After another hour, another 20% evaporates from the leaf surface, and only 5% is replenished through the roots.

Total : 40% of the moisture has evaporated and only 10% has been replenished, and daylight is still in full swing.

As a result, even a well-watered plant (sitting in a wet substrate) begins to wither, its leaves become flabby and lethargic.

The orchid more or less comes to its senses only in the late afternoon, when the direct sun leaves the windowsill and it begins to cool down.

The roots of orchids begin their work in full and at least partially replenish the moisture lost by the leaves.

Regular repetition of such overheating is fraught with the death of the orchid.

REMEMBER! Do not spray overheated orchid leaves!

The plant should be moved deeper into the room and left alone for 1-2 hours to allow the leaves to cool.

Only then spray, water or arrange “steam” baths for it (keeping the plant without watering in a steamed bathroom).

If the apartment has only northern windows , and there are trees in front of them and houses are located fairly close, then there are two options: either refuse to buy orchids, or install artificial light lamps above the windowsill.

When growing orchids, the ideal option is a combination of different windows .

In winter and autumn, keep plants on southern, south-eastern or south-western windows, and in spring and summer - on eastern, western or very light northern ones.

Does the shadow love?

Starting in March, when the sun rises higher and higher above the horizon, the risk that heat burns may appear on tender leaves increases. First of all, this applies to such a common type of orchid as phalaenopsis. In this case, the window should be shaded. This can be done using blinds, a light curtain, thick white paper or matte film. You can also rearrange, if possible, the plants 1-1.5 meters from the window.

If you are going on vacation, then you should not take risks with shading the south window to avoid negative consequences. The best option is to move the orchid on the nightstand, refrigerator, or even on the floor.

Light conditions in which the orchid is kept

The size and color of the leaves can often be used to judge the light conditions in which the orchid is kept.

Dark green long leaves indicate that this specimen is a resident of the eastern or northern window.

Smaller and lighter leaves (for some species with a small proportion of red pigment spots) indicate residence on the south or west side.

Situations arise when an orchid is brought home with long, fleshy leaves, and after several months the new leaves grow shorter and more rounded.

The fact is that the intensity of lighting has changed: there is more light than there was before. Orchids no longer need to grow long leaves to catch as much light as possible.

This is a completely normal reaction! This often happens even in the same window.

In winter and autumn it is a little dark - the leaves grow longer. In summer and spring , there is more light, causing the length of the leaves to shorten and the shape to change.

Do I need to highlight the flower additionally or not?

When there is not enough daylight, the orchid needs additional lighting with the help of phytolamps. For successful photosynthesis, chlorophyll molecules require a red and blue color spectrum. The blue color stimulates the development of leaf mass, the red color promotes flowering.

Phytolamps are: