The main and most effective LEDs for plants are blue and red with wavelengths of 660 nm and 455 nm
Why are they like this?
Let's look at the light absorption spectrum of plants:
">
Chlorophyll is green (absorbs blue and red).
Carotenes - yellow, orange, red (absorbs blue).
At the same time, different pigments absorb in different ways, and what they do not absorb, they reflect, and this is what determines the color of the plant itself.
Scientists have proven that the source of energy for photosynthesis is predominantly the red rays of the spectrum, as evidenced by the spectrum of activity of photobiological processes, where the most intense absorption band is observed in the red part, and the less intense one in the blue-violet part.
Why is the plant leaf green? Because its surface reflects, and therefore does not absorb green light. This property is explained by the presence of the chlorophyll pigment in the green leaf. And chlorophyll absorbs light (and therefore energy) from the red (660 nm) and blue (445 nm) regions of the spectrum daylight.
The yellow-green component of daylight is practically useless, there is a gap in the graph; red and blue light is needed for the growth and life of the plant.
Photomorphogenesis is the processes occurring in a plant under the influence of light of different spectral composition and intensity. In these processes, light does not act as a primary source of energy, but as a signaling agent that regulates the processes of growth and development of the seed. It turns out that in addition to chlorophyll, any plant has another wonderful pigment - phytochrome. A pigment is a protein that has selective sensitivity to a certain part of the white light spectrum.
The peculiarity of phytochrome is that it can take two forms with different properties, under the influence of red light 660 nm and far-red 730 nm, it has the ability to phototransform. Moreover, alternating short-term illumination with one or another red light is similar to manipulating any switch that has the “ON-OFF” position, i.e. The result of the last impact is always preserved. But here you still need to look for information or experiment yourself.
I will write about periods of illumination, the duration of day and night later!
This property of phytochrome ensures monitoring of the time of day (morning-evening), controlling the frequency of plant activity. Moreover, the light-loving or shade-tolerant nature of a particular plant also depends on the characteristics of the phytochromes it contains. This makes it difficult to create a universal lamp for all plants.
Phytochrome, unlike chlorophyll, is found not only in leaves, but also in seeds. The participation of phytochrome in the process of seed germination for some plant species is as follows: red light stimulates seed germination processes, and far-red light suppresses it. It is possible that this is why the seeds germinate at night. Although, this is not a pattern for all plants. But, in any case, red light is more useful because it stimulates, while far-red light suppresses the activity of the plant’s life processes.
Experimentally, we found that there should be more red. For different plants the proportions are different. It turns out that if tomatoes do well with a lot of red, then cucumbers begin to die or greatly enlarge their leaves.
Adeniums are plants that in their native places of growth receive the maximum of the red spectrum. In Africa and Arab countries, sunrises and sunsets do not last long, the sun sets and rises quickly, and there are very few cloudy days there. This means there is not enough blue light.
From various experiments, we came to the conclusion that the proportions of red and blue LEDs are approximately 1 blue: 2 red for the active phase of the growing season and
at the stage of ripening of fruits of light-loving plants, this ratio increases to 1:8
You also need to take into account the conditions in which the plants are located, whether natural light falls on them or not, and if it does, then mainly what kind? If the plants are in a grow box or, say, in the basement, then some plants will need other spectra, they can be given them if you install a certain number of white LEDs, you can also connect ultraviolet ones if required exotic plants. Almost all plants can grow without UV, but not all plants produce, say, essential oils. Example - Dill. Without ultraviolet light it is not as fragrant.
In greenhouses, two types of artificial lighting are sometimes combined - sodium lamps, which contain a lot of red spectrum, plus LEDs. After all, installing the required number of LEDs over large areas requires large investments.
In numerous reports and experiments, the following ratios are found:
for growing season from 1:2 to 1:4
for fruit ripening from 1:4 to 1:8
why so much red?
But it is worth considering that in greenhouses there is also natural light, which compensates for the necessary balance.
For growing in closed ground, usually 1:2 - 1:4 is used depending on the plants.
I also saw how mother plants are grown almost under the same blue spectrum, apparently for the further production of clones and their rooting.
The combination of spectra also affects the manifestation of sexual characteristics of plants. Cannabis has an appearance female plants increases sharply if the blue spectrum predominates during the first weeks of growth.
For adeniums, I would recommend a ratio of blue to red, with a wavelength of 660 nm and blue 440-445 nm, from 1:3 to 1:4. If you are not growing them in a grow box, you can add a little white. If you add green, the light will be white or almost white to the eyes, depending on the amount, but to the plants it will go unnoticed.
Power selection
It also depends on the location and conditions, as well as on the culture that will grow.
Plants can be roughly divided into light-loving, light-loving and fruit-bearing, and non-demanding.
Fruit-bearing, light-loving plants, such as tomatoes or strawberries. They need a lot of light and the more of it, the higher the yield.
Not demanding, these are lettuce, tropical plants, and many indoor plants. Well, they’re just light-loving, that’s understandable.
How much power do you need?
From personal experience and from observing others, I have concluded:
For greenhouses:
not demanding 10-40 W per m2
light-loving plants 20-60 W per m2
fruiting 50 W per m2 or more, can be increased several times.
Usually used in greenhouses to maintain the length of the day, so that it is not lower than 12/12, day/night; in the daytime, additional lighting increases growth and accelerates ripening, and also adds a red spectrum, which is very little on autumn and spring days.
Without natural light:
not demanding 40-80 W per m2
light-loving plants 50-100 W per m2
fruiting 150 W per square meter and more.
You need to know that the higher the lamp hangs, the less light there is, and if the distance is doubled, the light will be four times less. This is the quadratic relationship.
There are calculations for sodium and fluorescent lamps in lux and lumens. In the case of calculations with LED lamps for plants, it is necessary to take into account many components and are usually calculated simply in Watts. To give calculated data, you need to carry out a lot of calculations, and to measure with a device, you need identical lamps. After all, the illumination of 5 white LEDs will be much higher than 5 red ones with a wavelength of 660 nm. and the whites will be much less useful!
Lux is a unit of measurement of illumination. Lux is equal to the illumination of a surface area of 1 sq.m. with a luminous flux from a source of 1 lm.
In practice, the main importance is the illumination indicator at work surface, measured in Lux (Lux) using a special device - a lux meter.
Which LEDs to choose for plant lighting?
Blue and red LEDs with wavelengths of 650-660 nm in red and 440-460 nm in blue. Peaks occur at 660nm and 445nm
This does not mean that at wavelengths of 630 nm and 465 nm it will grow poorly, it will just be slightly lower in efficiency. I won’t say for how long.
Red light does not penetrate well through layers of foliage, blue light is better.
LEDs can be placed very close to the plant, up to 5 cm, without fear of scorching the plant. Very delicate leaves, it is still better to place them no closer than 10 cm from the upper leaves. When growing tall plants, you need to think about side lighting, since the lower tiers will not receive enough light.
For most of the year, there is very little light for plants. And those who grow them year-round indoors, and not seasonally outdoors, face big problems because of this.
The only way to solve them is to use artificial light sources. Which ones are better to choose and what to focus on?
Efficiency, safety and energy consumption
First of all, the average person pays attention to the level of electricity consumption. The more plants you have, the more lamps and bulbs you will need for them. 
There is no desire to pay more for electricity than the cost of the crop. Therefore, when purchasing lamps, much attention is paid to such a parameter as the efficiency of the light bulb.
The well-known bulb bulbs with an incandescent filament get very hot during operation. This is due to the fact that in them most of the electrical energy is converted not into light, but into useless heat. 
Therefore, they gradually began to abandon them and began to switch to energy saving lamps. Their efficiency is approximately 4 times higher than that of conventional ones. 
However, in fact, we received the same fluorescent lamps, although smaller in size, but containing mercury. If such a light bulb breaks, you will have to urgently take safety measures and carry out the so-called demercurization of the entire room.
Not only mercury itself, but also its vapors are poisonous to humans. And even in ultra-low concentrations they can cause serious consequences. 
Therefore, they were subsequently replaced by safer LED light sources. And phytolamps were developed specifically for plants. 
LEDs also high efficiency and minimal heating. And most importantly, they continue to improve and improve their performance year after year.
Which color is best for plants?
However, as it turned out, the efficiency of a light bulb is not the main thing in proper cultivation plants. The most important thing is their spectrum and how different it is from natural solar radiation. After all, all flowers, vegetables, fruits, and berries are accustomed to it.
What is hidden behind such a scientific name as the emission spectrum? To understand this, you have to remember what light is? And light is nothing more than an electromagnetic wave. 
Moreover, each color has a certain wavelength, hence the rainbow. However, different lengths mean not only different colors, but most importantly - different quantities energy.
Waves with shorter wavelengths contain more energy.
If all the colors are conventionally represented not in the form of the usual straight line, but in the form of balls, then the blue ball will be the largest in size. Green is smaller, and red will be the smallest. 
All colors are always simplified to these three types of R-G-B:
- red
- green
- blue
Why is the blue ball the most voluminous? Because its wavelength is the shortest. It is smaller than green. And green, in turn, has less than red. 
As a result, it turns out that red carries the least energy, and blue carries the most. 
And here many may have a logical question: “Is there a difference in which spectrum to illuminate the plants?” And if there is, can this knowledge be somehow used for business?
After all, if some color turns out to be more effective, then there is nothing easier than directing all the energy to the plant only from it. If blue is the boldest color, it is enough to illuminate the plants only with it and get a great harvest all year round. 
However, everything turns out to be not so simple. Here one more characteristic of light needs to be taken into account - its qualitative or spectral composition.
Light absorption by plants and photosynthesis
To understand how individual colors affect the efficiency of photosynthesis, scientific experiments. Individual pure chlorophylls were isolated from the whole leaf. After which, for a long time, they were illuminated with light of different spectrums and the results were checked. 
In this case, first of all, we looked at the efficiency of CO2 absorption, that is, the intensity of photosynthesis. Below is the final graph of such an experiment. 
It shows that chlorophyll is mainly absorbed in the blue and red regions. In the green area the efficiency is minimal.
However, they didn’t stop there and conducted another experiment. Plants also contain carotenoids. Although they play a minor role, they should not be forgotten.
So, a similar experiment with carotenoids showed that the previously isolated leaf pigments in this case absorb light predominantly in the blue region of the spectrum. 
After looking at this, everyone unanimously decided that the green color is absolutely useless and can be neglected. All experts suggested focusing only on blue and red light.
And accordingly, it was considered more correct to choose light bulbs that emit these spectra the most. 
But as it turned out, the initial mistake of the experimenters was that they did not use the entire sheet, but isolated pigments from it and looked at the results only from them.
In fact, light is scattered very strongly in a single sheet. We carried out more experiments, but this time we looked at the entire leaf and used different plants. As a result, we obtained data that more accurately showed how effectively light is absorbed by the entire leaf, and not by its individual “pieces.” 
On the one hand, blue and red light dominate here again. Individual peaks in photon consumption reach up to 90 percent. 
However, to the surprise of many, the green rays turned out to be not as useless as previously thought. The fact is that, thanks to its penetrating ability, green supplies energy to deeper areas of foliage where neither red nor blue can reach.
Thus, if you completely abandon green, you may inadvertently destroy the plant, and you will not even understand the reason. 
It turns out that everything colors R-G-B are normally absorbed by the leaves and you should not throw away any one of them. That's just the need for energy different colors different plants have different values.
What kind of light do plants need most?
In order to explain this more clearly and clearly, let’s draw an analogy with something edible. Let's say you have a ripe peach, raspberry and pear on your table. 
It doesn't matter to your stomach what you eat. It will digest all berries and fruits equally well. But this does not mean that there will be no difference for you later. Different foods still affect your body differently.
Eating 10 strawberries is not the same as eating 10 pears or peaches. You have to find a certain balance. 
The same thing happens with light for plants. Your task is to correctly select how much of each light should be in the overall spectrum. This is the only way to count on rapid growth.
Most main question- which light will be considered the best? It would seem that there is no guesswork here. Best option this is sunlight and its close analogues. 
After all, for millions of years, plants developed under it. However, look at the picture below. This is what the intensity of sunlight actually looks like. 
See how much green there is here. And as we found out earlier, although it is useful, it is not to the same extent as other rays. When they say that sunlight is the most effective and there is nothing to deviate from Mother Nature, they do not take into account one simple fact.
In real life, and not in experiments, plants adapt not only to sunlight, but also to the conditions of their environment in which they grow.
Let’s say that at the depth of a reservoir, where some greenery grows, blue color dominates. But in the forest under the canopy of trees, green comes out the winner. 
But in some cases, significant questions arise about its effectiveness. Here is the optimal distribution of spectra for our two most popular vegetables - cucumber and tomato: 
Just these two elementary examples between a cucumber and a tomato clearly show how different their needs are. And if you illuminate both vegetables at once with the same light bulb, the results will be completely unpredictable.
Circadian rhythms
In addition to the correctly selected spectrum, two more parameters play an important role - time and lighting rhythm. 
All plants were originally grown outside in natural sun. And the sun, as you know, does not hang at its zenith 24 hours a day. It rises in the morning and sets in the evening. That is, the natural light intensity first gradually increases, and in the second half of the day, having reached its peak, it begins to fall.
This is the so-called rhythm. And plants feel it well. Change the rhythm without changing anything else, and your vegetables may begin to ache and feel off-kilter. 
That's why experienced gardeners three groups of plants were identified - short, long and neutral day.
Here are some of their varieties: 
A long day is when light intensity is observed for more than 13 hours. Short - up to 12 hours. Plants for a neutral day do not care when they ripen, be it short or long. 
The performance of the entire growing system is determined by a quantitative evaluation criterion - for example, the useful mass of dry matter or the volume of the target leaf/root extract. For a qualitative assessment, you can analyze the chemical composition of plants and morphology (deviation of the shape and size of the stem/leaves/fruit).
For most crops best harvest and product quality can be obtained by providing plants comfortable conditions, where all basic physiological needs are as close as possible to natural levels.
Thus, in most practical problems, a plant grown under natural conditions can be taken as a standard for comparing and evaluating the results of artificial cultivation. Natural conditions for a particular crop, usually correspond to the climate in the region of its original origin.
Basics
Considering the process of growing plants as closed system, the following main factors influencing the result can be identified (see Fig. 1):
Sunlight, the main source of energy
- carbon dioxide (CO2) content in the air (carbon is the main element used to form new cells)
- water, mainly as a source of oxygen included in its composition, necessary for the photosynthesis reaction
- ambient temperature.
Rice. 1
Optimum photosynthetic temperature for most plants middle zone is approximately 20-25°C. For example, for sunflower, an increase in temperature in the range from 9 to 19°C increases the intensity of photosynthesis by 2.5 times.
Thus, during photosynthesis, due to light energy, the formation occurs organic matter(carbohydrates) with the participation of chlorophyll. Chlorophyll (from the Greek χλωρός, “green” and φύλλον, “leaf”) is a green pigment that colors plant chloroplasts in green.
So the amount of light is important factor, affecting the intensity of plant growth.
Also, over many years of evolution, this process has adapted to the day/night cycle. During the day, under the influence of light, water is divided into oxygen and hydrogen, and the plant stores energy and nutrients. At night, in the dark carbon dioxide under the influence of stored energy, it combines with hydrogen, forming carbohydrate molecules, i.e. the actual growth of culture occurs.
Thus, when growing plants artificially, it is important to provide not only high illumination, but also the correct cyclicity of light switching on in order to get the best result.
About spectra
Modern LED technologies make it possible to format complex plant lighting spectra. Let's consider how the spectrum affects the growth process.
In Fig. Figure 2 shows in detail the energy absorption spectra of the basic plant pigments.
Rice. 2
It can be seen that in addition to the traditionally mentioned chlorophyll pigments with absorption peaks in the range of 400-500 nm and 650-700 nm, growth processes are also influenced by auxiliary pigments from the family of light-harvesting phycobiliproteins.
In some studies, the absorption spectra of the main pigments are summed to form a “universal” spectrum, the shape of which is shown in Fig. 3.
Rice. 3
Photosynthetically active radiation (PAR) is used to quantify the effect of light on plants. In English literature - Photosynthetic Photon Flux (PPF). PAR/PPF flux is measured as the number of photons emitted by a light source that can be absorbed by a plant during photosynthesis (wavelength range 400 to 700 nm).
The PPF value is calculated without taking into account uneven absorption by the plant different energies different wavelengths. Therefore, in addition to PPF, the YPF value is sometimes used - Yield Photon Flux - the so-called. the photon flux absorbed by the plant. To calculate YPF, the weighted PAR value and the photosynthetic efficiency spectrum are used as weighting factors.
The spectrum of photosynthesis efficiency is shown in Fig. 4.
Rice. 4
The Photon-weighted curve converts PPFD to YPF; The energy-weighted curve allows you to do the same for PAR expressed in watts or joules.
Let us take a closer look at how radiation affects plants in different parts of this range.
Ultraviolet C (280 - 315 nm)
Irradiation of plants with such radiation has negative consequences and can lead to cell death and discoloration of leaves/fruits.
Ultraviolet B (315-380 nm)
This radiation has no visible effect on plants.
Ultraviolet A (380 - 430 nm)
Overdose ultraviolet radiation may be dangerous for foliage, however, small doses of radiation are absorbed during flowering and fruit ripening and affect the color and biochemical composition (taste). As a rule, the doses received by the plant under the influence of natural light are sufficient to support these processes.
Blue light (430-450 nm)
As shown above, this part of the spectrum is well absorbed by most of the plant's major pigments. This part of the spectrum can influence plant morphology: bush/leaf size and shape, stem length. A number of studies show better efficiency blue color at an early stage of plant development (vegetative phase).
Blue light promotes the opening of stomata, an increase in the amount of protein, the synthesis of chlorophyll, the division and functioning of chloroplasts, and the inhibition of stem growth.
Green light (500-550 nm)
A significant part of this range is reflected from the leaves, but the role of this part of the spectrum on the full development of plants cannot be underestimated. For example, green radiation, reflected from the upper leaves of a plant, has better penetrating ability and contributes to a more uniform development of leaves at lower levels, located in the shadow of larger neighbors (Fig. 5).
Rice. 5
Also, controlling the level of green in the irradiation spectrum allows you to control the time of onset and duration of the germination and flowering phases.
Orange light (550-610 nm)
From the point of view of the chlorophyll absorption spectra discussed above, this range has an insignificant level of response. However, the successful experience of using sodium lamps, the radiation of which mainly lies in this range, confirms that, in fact, plants are able to develop even with a non-optimal spectral composition of lighting.
Red (610-720 nm)
The most effective range, in terms of the number of photons absorbed by the plant during all stages of development.
Red light promotes flowering, bud sprouting, stem leaf growth, leaf abscission, bud dormancy, etiolation, etc.
Far red (720-1000 nm)
Despite the insignificant response in the absorption spectra of the main pigments, the far red range performs a kind of “signal” function - as in the case of green, adjusting the level of far red allows you to influence the time of onset and duration of the flowering and fruiting phase.
Infrared (1000 nm and above)
All radiation in this range is converted into heat, which further affects the temperature of the plant.
It should be remembered that for natural sunlight, more than 50% of the energy is emitted in the infrared range. If the plant is in artificial conditions x is irradiated only in the range of 400-700 nm, then it is necessary to additionally provide a power reserve in the heating system to maintain a comfortable temperature.
Plant needs at different stages of growth
As noted above, light is not only a source of energy that controls photosynthesis. Various areas spectrum is perceived by the plant as signals influencing many aspects of growth and development (germination, deetiolation). Changes in plant development associated with light are the result of photomorphogenesis.
The diagram in Fig. 6 shows the main effects stimulated by different colors throughout life cycle plants.
Rice. 6
Let's take a closer look at the influence of light at various stages
Chlorophyll synthesis
The most large number chlorophyll is produced in blue light, less in white and red light, and the least in green light and in the shade. Under different light conditions, the ratio of chlorophyll A and B is also not the same. The most big difference in the ratio of A and B under yellow and blue light. Red light promotes greater production of chlorophyll type A.
Blue light is suitable for light-loving plants, shade-loving plants red light is coming.
Bloom
The relationship between the length of the light period and the dark period is called the photoperiod. The total length of a day is 24 hours, but depending on different latitudes and seasons, the length of day and night is not the same. Depending on different climatic conditions and places of growth, the photoperiod of different plants is not the same. Flowering, leaf fall, bud dormancy - all this is a plant’s response to a change in photoperiod.
Plants that are ready to start flowering will flower when the photoperiod is right. The number of days before flowering begins is determined by the age of the plant. The older the plant, the faster it will bloom. Plant leaves are affected by photoperiod. The sensitivity of leaves to changes in photoperiod is related to the age of the plant. The sensitivity of old leaves and young leaves is not the same. Growing leaves are the most sensitive to changes in photoperiod.
Accumulation nutrients and plant growth are regulated by radiation in the red and far-red range. Reproduction is determined by blue light. The phytochrome contained in the leaves can receive red light and high beam signals. The plant is ready to flower, will bloom if the last radiation is red high beam.
In Fig. Figure 7 shows the absorption spectra of plants during chlorophyll synthesis, photosynthesis and photomorphogenesis.
Rice. 7
LEDs
Modern high-power LEDs used in artificial lighting plants, allow the formation of monochrome radiation in virtually any part of the spectrum discussed above.
Examples of LED spectra are shown in Fig. 8
Rice. 8
It is worth noting LEDs with a wavelength of 450 nm (“deep blue”) and 660 nm (“far red”), as components that coincide with the absorption peaks of chlorophylls. As noted above, the presence of LEDs with emission peaks in other parts of the spectrum makes it possible to further stimulate other parts of the absorption spectrum. White phosphor LEDs (gray curve in Fig. 8) have in their spectrum a relatively wide region of phosphor emission, as well as a blue peak of blue crystal radiation not absorbed by the phosphor.
LED combination various colors in one lamp with the possibility of independent control allows you to create virtually any spectrum for a specific crop and phase of its development.
Examples of spectra used in various plant lighting scenarios are shown in Fig. 9
Rice. 9
Separately, it is worth considering the spectrum of radiation received by a plant when it is exposed simultaneously to natural radiation and radiation from an LED illumination system.
Let's assume. that the illumination lamp uses blue and red LEDs in a ratio of approximately 1:2 (in terms of energy level) to stimulate chlorophylls at the stage of vegetative growth.
An example of such a spectrum is shown in Fig. 10
Rice. 10
In reality, the leaves of plants will also be affected by the spectrum of solar radiation, and the total spectrum of irradiation will look like this (Fig. 11).
Rice. 11
It can be seen that in this case, the plant receives monochrome supplementary lighting in combination with broadband natural radiation to produce a spectrum that stimulates all the main absorption zones of the plants. The resulting spectrum is close in shape to the total absorption spectrum of all the main plant pigments discussed above.
Conclusion
To summarize this review, we can note the following:
The spectral composition of light is an important factor for the productive cultivation of crops in artificial conditions, however, it is not primary. You can get an increase in yield by optimizing the spectrum by providing the plant with a sufficient level of basic needs (temperature, water, CO2, ventilation). The amount of light is also a higher priority parameter compared to its spectral composition.
Modern LEDs make it possible to effectively generate radiation in the spectral absorption range of plants. Moreover, it is possible to use the so-called. monochrome LEDs with different colors (emission wavelengths) and traditional white “phosphor” LEDs, providing uniform broadband radiation.
The presence of LEDs with different colors in the lamp and the technology for independently controlling them allows you to study the influence of the spectrum on the efficiency of growing a particular crop in specific conditions and develop an optimal balance of colors for better yield.
References
Physiology of plants. N.I. Yakushkina. Publisher: "Vlados". Year: 2004
Research on the formation of chlorophyll in plants. Monteverde N. A., Lyubimenko V. N. News of the Imperial Academy of Sciences. VII series. - St. Petersburg, 1913. - T. VII, No. 17. - P. 1007–1028.
Creation of effective LED phytolights. Saken Yusupov, Mikhail Chervinsky, Ekaterina Ilyina, Vladimir Smolyansky. Semiconductor lighting technology N6’2013
Contributions of green light to plant growth and development. Wang, Y. & Folta, K. M. Am. J. Bot. 100, 70-78 (2013).
Lighting is not always enough for indoor plants. Due to its deficiency, shoots may develop slowly. To correct this oversight, you just need to install a plant lamp. It is such a lighting device that can create the desired color spectrum.
LED lighting fixtures received wide application for lighting greenhouses, in open gardens and so on. They are an excellent alternative to sunlight, do not involve high costs and have long period operation.
Plant photosynthesis is a process that occurs when there is sufficient light. In addition, the plant can develop correctly due to the required ambient temperature, sufficient humidity, light spectrum, length of day, and the presence of the necessary chemicals.
There are no flowers that can fully grow in dark time days. Some lighting is definitely needed. The difference is in its intensity. In general, daylight lasts approximately 15 hours and it does not matter how it can be maintained - sunlight, artificial lamps, or both. There are plant species for which determining the light they need depends on changing conditions. Although there are those who only need certain lighting. It is not needed by flowers that rest at night. For some varieties, it is recommended to receive sunlight in winter.
The full growth and development of vegetation is affected by the following factors: proper watering, required temperature, optimal humidity, sufficient feeding, selection of necessary lamps for plants. The latter is necessary for growing using artificial light. And this great solution for those plant species that have already been able to adapt to dim light, for example, begonias.
How to determine the sufficiency of light?
It is recommended to install the lighting fixture for indoor plants correctly. Therefore, first we find out whether strong lighting is necessary for a particular planting.
Then we determine the number of LEDs. You can count them using a lux meter. You can calculate their number yourself.
- Light spectra for plant development.
Let's consider what light spectra are needed for plants:
- Chlorophyll is green.
- Carotenes – yellow and red spectra.
In addition, various pigments can absorb light in different ways; they reflect all that is unnecessary.
According to scientists, the source of energy for photosynthesis is mainly the rays of the red spectrum.
Photomorphogenesis is a process that occurs in a plant under the influence of light with different spectral composition and saturation. Here light is a signaling agent that regulates the growth of seedlings. In addition, the plant also contains the pigment phytochrome. The pigment is a protein that is sensitive to a certain region of the white spectrum.
The peculiarities of phytochrome are that it takes 2 forms with various characteristics; under the influence of a red hue with a wavelength of 660 nm, it is distinguished by its phototransformation ability. In addition, alternating the red light for a short period of time is similar to manipulating it using any switch.
This phytochrome characteristic may provide time-of-day tracking to control the frequency of seed growth. Making the right lamp is quite difficult.
Phytochrome is also present in leaves and seedlings. Red rays stimulate the germination of seedlings, and a distant shade of the same color suppresses its growth. This is probably the reason why it germinates at night. However, this is not a pattern for all plant species. However, red light is beneficial because it stimulates active life processes in the plant.
As it became obvious from the results of numerous experiments, there should be more red color. For different seedlings, the optimal proportions can be very different. So it turns out that if tomatoes grow well with an abundance of red, then cucumbers may die.
Adeniums, for example, are plants that grow in their native lands, receiving quite a lot of the red color of the spectrum. In African territories and Arab countries, dawn and sunset do not continue long time, the sun sets and rises very quickly. In addition, these regions are characterized by few cloudy days. That is, there is little blue light there.
The results of numerous experiments have led to the conclusion that the ratio of 2 red and 1 blue LEDs is better for the growing season of plant maturation. Moreover, thanks to this light ratio, you can greatly increase the number of fruits.
In addition, we take into account the conditions in which the plant grows and whether it receives direct sunlight. If plants are grown in a special grow box or in basement conditions, then other spectrums will have to be used to grow them. Such spectra can be obtained by installing a certain number of white LEDs; you can also add ultraviolet ones if you grow exotic varieties. Almost all plants can grow without ultraviolet rays, but not all plants can produce, for example, essential oil. We can look at the example of dill, which without UV is not so fragrant.
IN greenhouse conditions in some cases, two types of artificial lighting devices are chosen simultaneously - a sodium lamp, which contains an abundance of the red spectrum, and an LED. To mount on large area the required number of LEDs will require a huge investment.
However, it is also necessary to take into account such important points, such as the fact that in greenhouse conditions ordinary light is also available, which can compensate for the lack of lighting.
To grow in closed soil, you can use a ratio of 1:2 – 1:4 depending on the growing plant. It can also be grown under the only blue spectrum.
Also, thanks to the combination of different spectra, you can notice the manifestation of sexual characteristics of plants.
- Color temperature of lamps.
- 2,700 K refers to warm light– there is more of the red spectrum that can be obtained from incandescent lamps. Other types of lamps can produce a glow that is close to the light of incandescent lamps. This type of glow is used during the flowering period.
- 4 100 K – white light.
- 6,400 K - cold white light - blue spectrum radiation predominates here. This may lead to the best result during vegetative growth. That's why cold light so in demand.
- 8,000–25,000 K – ultraviolet.
- Power selection.
You can determine the power based on the location, conditions and crop that you are going to grow at home. Plants are light-loving and fruit-bearing. Among the latter are tomatoes and strawberries. They need an abundance of light, which determines their productivity. Undemanding plants include lettuce, tropical plant varieties and most indoor plants.
LEDs can be located quite close to the plant, at a distance of about 5 centimeters, without scorching the plant. If the leaves are very tender, it is recommended to install the lamps at a distance of about 10 cm. If you grow high grades plants, it is better to provide side lighting, because lower leaves may not receive enough light.
- Length of light waves.
The spectrum of the sun's rays contains both blue and red shades. They enable plants to gain more mass and bear fruit better. If you only irradiate with the blue spectrum, which has a wavelength of approximately 450 nm, your seedlings will grow stunted. It will not please you with an abundance of green mass. It is also likely that the plant will not bear fruit.
If you provide the red range of light with a wavelength of approximately 620 nm, then it will begin to develop well root system plant, it will bloom and bear fruit well. From all of the above, we can conclude what kind of light is needed for certain plants.
Choosing a lamp to illuminate plants
- LED lamps.
If you choose LED lamps to illuminate your plants, they will help your flora not only grow well, but also bear fruit well. At the same time, when illuminated by a fluorescent device, flowering also occurs. LEDs will not heat up, so there is no need to ventilate the room. In addition, there is no thermal overheating of plants. Such phytolamps are an excellent choice for growing seeds. Due to the directionality of the radiation spectrum, shoots can grow stronger even in a short period of time.
Among the advantages, it is worth noting low electricity consumption. LEDs can only yield sodium lamp. However, they are 9 times more economical than incandescent lamps. Their service life can even reach 10 years. The warranty is provided for a period of approximately 4 years. If you choose such lighting fixtures, you can forget about replacing them for a long time. They don't accumulate harmful substances. Although their use in greenhouses is quite widespread. The market today is full of such lamps: they can be attached both to the wall and to the ceiling.
Fluorescent lamp for growing plants
To increase the radiation intensity, the lamps are combined into one design. Among the disadvantages can be noted high price, when compared with fluorescent lamps. The difference is very big. However, diodes can pay for themselves after a couple of years of operation. With their help you can significantly save energy. After the warranty period ends, you may notice a decrease in the glow. If the greenhouse area is large, then you will need to install as many lighting points as possible.
- Radiator for lamp.
Such devices are required in cases where heat needs to be removed. Radiators do an excellent job of this. It is recommended to alternate LEDs for plants by color. This will give you even lighting.
- Phyto-LEDs.
A new invention called phyto-LED may replace conventional analogues, which shine only in a single color. The new technology in a chip contains the necessary spectrum of LEDs for plant germination. It is necessary for various stages of growth. The design of the simplest phytolamp consists of a block where both LEDs and fans are installed. The latter can be adjusted in height.
- Fluorescent lamps.
For a long time, fluorescent lamps were quite in demand in personal plots and in greenhouses. However, such devices for plants are not the best solution for the color spectrum. They have been replaced by the latest phyto-LED light bulbs for special purposes.
- Sodium lamps.
Such devices have very intense light and are best not installed indoors. It is recommended to use them in a large greenhouse, garden and greenhouse where careful lighting of plants is needed. The disadvantage of these lamps is their low performance.
As you know, all plants for their proper development and good growth requires light, which winter period critically lacking. In order for the seedlings to grow full-fledged, strong, fruit-bearing, and for indoor plants to delight with flowering, additional effective lighting is needed, which can be organized using LED phytolamps.
LED lamps for plants they have the most suitable light intensity and spectrum for growing. Their advantages also include long term operation, energy saving, ability to adjust lighting intensity, they do not overheat, can work in different temperature conditions(from -25 to +40). Lamps of this type are used in the most different rooms: private house, apartment, greenhouse.
Types of LED lamps for plants
Depending on how many plants need to be illuminated, what area they occupy, whether the illumination is used for personal growing purposes or for production purposes, LED phytolamps are distinguished, having the following forms:
- Pipe. This lamp shape is suitable for illuminating “green” lights located in long in narrow rows. Ideal for use on window sills.
- Spot single lamp. It is mainly used for a small number of plants: several flowers, a box of seedlings.
- LED panel. Represented in large rectangles or squares. More relevant to professional lighting, for example, large racks with seedlings.
- LED strip. It is quite common, since it is possible to arrange the light at your own discretion, in a certain quantity and from a certain direction, using the necessary combination. This type of lighting is assembled by hand.
- Spotlights. Also more suitable for professional use. Illuminates a large area from a long distance.
When choosing an LED lamp, you need to read its instructions for use, which will indicate the exact amount of area it illuminates, from what distance such an area is covered, and the lighting efficiency.
Which LEDs to choose for lighting?
Not all light is effective for growing crops. LEDs for phytolamps are distinguished by spectrum, or color of illumination, which affects development, growth and flowering.
Certain spectra affect the plant as follows:
- Blue, blue-violet spectrum(430-490 nm.) It promotes vegetation, density, strengthening, correct formation root system. This light is used more intensively at the initial growth stage, for example, when growing seedlings.
- Red, red-orange spectrum(600-780 nm.) It is favorable at the flowering stage, responsible for the development of fruits and leaf growth.
All other spectra - green, yellow - have virtually no effect on plants, and ultraviolet light can even be harmful.
To effectively illuminate “green” plants, it is necessary to select LEDs of blue and red spectra, combining them correctly at each stage of crop development. This combination depends largely on the characteristics of the plant being grown - what exactly it needs at one time or another during its development. Therefore, it is necessary to thoroughly familiarize yourself with the lighting requirements of the culture.
Practically universal choice is a full spectrum LED that is based on a combination of red and blue colors:
- LED strips for plants are produced in ratios of 10:3, 15:5, 5:1 blue to red, respectively.
The most optimal are strips with a ratio of 5 blue LEDs to 1 red, but only if the green pets are on the windowsill and receive enough light from the outside.
- LED phytolamps They usually contain 60-80% red and 40-20% blue. A lamp with 75% red radiation and 25% blue is considered sufficient for most plants.
It is worth noting that LEDs also differ in lighting power.
Lighting time
In order for LED lamps as illumination to give maximum results, it is necessary not only to take into account the appropriate spectral analysis of specific plants, but also the light-dark ratios they require. With a lack of light, they will develop poorly, but an excess of it also does not bring anything good.
To regulate the duration daylight hours you need to approach it wisely. For plants with short daylight hours, 12 hours of lighting will be enough, but for crops that require long days, 14 may not be enough.
Some light timing options for certain categories:
- Seedling. At the initial stage, it requires round-the-clock light attention, so the lamps shine all day long. Then this figure is gradually reduced to 16-14 hours.
- Plants with winter suspended animation, which include , . They prefer in winter time a small amount of light, 10 hours will be enough for them.
- Flowers that love diffused shade. These include ferns and tradescantia. They grow well with 10-12 hours of light per day.
- Plants that require bright, long-lasting light to grow and bloom successfully. These are representatives of roses, as well as myrtle, eucalyptus, and jasmine. They require 14-16 hours of light in winter. Sometimes this figure can reach up to 18 hours.
- There are also crops that are average in light-loving, which special conditions no lighting required.
And one more important fact: Female types of plants are more demanding in terms of light duration than male ones.
How to place LED phytolamps?
LED lamps are highly directional. Due to the fact that they have a lens, the light flow is concentrated in one direction. Therefore, it is best to place such phytolamps close to the plants. To receive effective result this distance varies from 15 to 30 cm. There is no need to fear that the crops may “burn out”, because the LEDs do not heat up and do not emit heat.
When organizing the arrangement of lamps, the following points must be taken into account:
- Plant height. For uniform light exposure on each bush, it is necessary that they be approximately the same height. Otherwise, the light may not reach someone. As an option, they use supplies for short people to equalize with tall ones.
- Plant arrangement. It should be done depending on the light intensity.
In the center of the illumination provided by the lamp, the light is more powerful and intense, so this is where the more light-loving and fastidious crops are placed, and the rest are placed at the edges.
Best performance when positioned vertically Lamp arrangement options can be:
- above;
- below;
- on the side.
Lamps located on top have the greatest impact, because the sun, a natural source of light, is located there. Side and bottom lights are most often used in stores for effectiveness.
Calculation of the number of lamps
For the favorable development of plants, they need not only a certain light, but also its sufficiency.
For calculation required quantity LED lamps at certain conditions, you need to know the following aspects:
- the lighting requirement for a specific crop (measured in lux, lux), but 8,000 lux will be sufficient for most;
- illumination angle;
- distance to bushes;
- square.
As a rule, the required quantity is first found luminous flux, which is determined in lumens, for a given area. To do this: number of suites required * number of square meters.
For example, for growing seedlings requiring at least 5000 lux on a window sill measuring 0.6 square meters. m., you need 3,000 lumens of light (5,000 * 0.6).
Do not forget about the distance, as it increases the loss of efficiency increases. They are approximately taken into account as a percentage. If the distance from the bush to the lamp is 30 cm, then the losses will be about 30%, which means that the required number of lumens should be added by these percentages.
The size of the luminous flux produced by a certain brand of LED lamp must be indicated on its packaging or in the instructions for use. Based on this, the number of lamps per required total number of lumens is calculated. Others will be printed on the packaging technical specifications, which will help you determine the angle of illumination, as well as the optimal distance.
In most cases, for one standard window sill with seedlings, 2 5 W bulbs are enough illumination.
Real reviews
Denis
“I decided to experiment with LED lamps. Unexpectedly, but the result pleased me. Lettuce and parsley really reach out to the lamp, even when the sun is shining!”
Christina
“I bought a Sidor phytolamp 5 years ago. I still can't get enough of it. It does not heat up, does not flicker, consumes less than 18 W, and perfectly and very effectively illuminates the entire balcony. I highly recommend it."
Evgeniy
“I thought for a very long time before purchasing led lamp for plants Volya “Fitosvet-D”. Red and blue diodes, it’s unclear whether they will be of any use, and they’re a little expensive! But I took it and didn’t regret it. The result is superb, the growth rate of greenery and seedlings has increased, and they themselves are fatter. So there’s a point!”