Artificial lighting
Light, a basic need
All gardeners know that light is an element that is of paramount importance for the growth of their plants. Some plants, such as cacti and succulents, require intense direct light, while others, such as most tropical plants, prefer to avoid direct sunlight and thrive in indirect, rather moderate light. The effects of insufficient lighting are easily observed: wilting, plants without vigor, loss of colors, etc.
In this article, we will see why light is so important for our plants and also how we can provide them with artificial lighting if our light conditions are insufficient.
Photosynthesis
It would be difficult to understand the importance of light in depth without first going through some notions of plant biology.
We know that plants need light. But do we really know and understand why? In fact, by capturing light, plants actually manufacture their fuel, their food! The equation is quite simple, lack of light = lack of food.
Let's look at this in more detail, but simply.
Plants are made up of plant cells in which various organelles (components) interact with each other. Among these organelles: chloroplasts. Chloroplasts, by their chlorophyll content, are responsible for the physiological process of photosynthesis by which plants use light energy and transform it into another energy, chemical this time. Indeed, with the process of photosynthesis, plants have the formidable capacity to take the energy given to them by light to transform water (H2O) and carbon dioxide (CO2) (captured by the stomata of their leaves and by their roots) into sugars (carbohydrates) and oxygen (O2).
The process of photosynthesis and the cellular activity of plants could be explained in more detail, but for our purposes here we will limit ourselves to these explanations.
Let's add that photosynthesis takes place mainly in the leaves of plants which act as light sensors. The upper leaves, often more exposed to light, will have a higher photosynthetic activity than the lower leaves, often less exposed to light.
Factors that affect photosynthesis
Photosynthesis is therefore a process that regulates the internal activity of plants and on which both their growth and their needs depend.
Some external elements have a direct influence on the process of photosynthesis, such as temperature, carbon dioxide content, the amount of water and nutrients, some internal factors and illumination.
There is no perfect temperature for all plants. It all depends on their origins, but generally speaking, we can say that the colder it is, the more the plant's physiological activities are slowed down, and therefore the less photosynthesis there is. This is what happens, for example, when a state of dormancy is induced in certain plants. The opposite effect also exists: a warmer temperature (within the limits of what is possible for plants, do not try to put your plants in the oven!) will have the effect of increasing the internal activity of plants.
The carbon dioxide content also affects photosynthesis. The more carbon dioxide there is in the air, the more photosynthesis takes place. Here too there is a limit: when the plant is saturated, it closes its stomata and blocks the entry of carbon dioxide. The question of carbon dioxide is interesting for growing areas where ventilation is less or not active. For example, greenhouse operators in winter sometimes use carbon dioxide injectors to meet the needs of their crops.
Water and nutrients (mineral salts) are essential for photosynthesis. A plant in water deficit will close its stomata and will not photosynthesize anymore, in order not to run the risk of dying of desiccation. As far as nutrients are concerned, to be able to produce chlorophyll and photosynthesis, a plant needs elements such as nitrogen (N), phosphorus (P), magnesium (Mg), chlorine (Cl), iron (Fe), manganese (Mn), boron (B) and zinc (Zn). A deficiency of one of these elements will affect the whole process.
The other factor that has a great impact on the process of photosynthesis, and not the least, is the illumination. Illuminance consists of both the quality of light and the quantity of light, and it is when both are present that a plant can photosynthesize efficiently. Photosynthesis increases with illumination up to a point of saturation (maximum photosynthesis) and decreases sharply as light decreases. There is a critical light stage, however, below which the plant will remain in a vegetative state, without showing any activity if light does not increase.
If this is your case, if you love plants, but you don't have enough natural light in your home to keep them beautiful. That they wither, don't grow, go through so much stress that they end up with a lot of pests, or die... Well, it's time to see what artificial lighting can do for you.
What do we know about light?
When shopping for artificial lighting for our plants, we need to have some basic knowledge. We often see grow lights that cast a purple light while others often cast a white... Which one to choose? How do we know what is appropriate for our plants?
Let's look at a few concepts to better understand the rest of the article.
Light is made of photons (particles) that move in waves (wave motion). Each wavelength corresponds to a color of light (red has a fairly long wavelength (700 nm), while violet has a shorter wavelength (400 nm).
The white light is in fact composed of a set of colors (thus a set of waves of different lengths), as we can see it when for example we make cross the light in a crystal prism (or that we observe a rainbow).
Not all white light is equal, because it does not contain the same proportions of each color. There are warm whites (which contain more yellow, orange and red) and cold whites (which contain more violet, green, blue). The color of light is measured in degrees Kelvin: 1,000K represents a very warm white, 10,000K a very cold white. The light of a bright sun, without clouds, is 6 500K.
The color or wavelength of light is what we call the quality of light, which we mentioned earlier. This little detour to explain that the plant reacts differently depending on the wavelength (or color of light) it receives. For example, blue-violet light is absorbed by the chlorophyll during the growth phase of the plant, it favors stronger plants, with a bushy habit, increases metabolism, growth and development. Red light is absorbed during the flowering phase. It will tend to influence the smell and taste of plants by increasing their concentration of oils and sugars. It is also the red light that influences the photoperiod (the plant knows it is daytime when it receives daylight and knows it is nighttime when it does not), which is useful for some types of flowering crops. And it can sometimes promote wilting, which is not desired.
Remember that the sun presents the full spectrum of light colors. We can ask ourselves if lamps that provide only purple light meet all the needs of the plants.
The other aspect of lighting, the quantity of light, is also very important. The best quality light, if not present in sufficient quantity, will not meet the needs of our plants. Generally speaking, the more light plants receive, the more active their metabolism becomes, and the more they grow. To this equation, we must naturally add water, relative humidity, nutrients and adequate temperature.
The unit of measurement for illuminance is the lux* (international system). To give an idea, a sunny summer day is over 50,000 lux of illumination while a well-lit room in a house varies from 100 to 500 lux. The interior of a house with a window in full sunlight, this time, gives about 60,000, while a cloudy day 2,000 lux. In addition, the further away from the light source, the more the amount of light received decreases. This goes without saying, one thinks, but what is surprising is that if there is, say, twice the distance, there will be four times less light! It goes down fast.
It is estimated that full sun plants (cacti and succulents for example) need 20,000 to 30,000 lux to be able to photosynthesize efficiently, while shade plants (some tropical plants such as Calathea or Sansevieria) can make do with 2,000 to 5,000 lux.
In addition to this, the windows of modern houses are composed of more layers than before and often block certain types of rays. It is not uncommon to have plants that are well exposed in a window, but that never seem to be satiated, and continue to grow in pride (to wither). It is difficult to give them more without resorting to artificial lighting.
* On the packaging of lighting products, we will often see the unit of measurement of illuminance in lumen. The difference is that the lux corresponds to the amount of light received while the lumen corresponds to the amount of light diffused. To have an equivalence, we must consider that 1 lux = 1 lumen /m2.
Artificial lighting
In order to optimize the growth of our plants indoors with artificial lighting, we must try to provide them with an illumination that is as close as possible to sunlight, powerful (lux) and balanced (in terms of the color spectrum).
In some cases, the choice of lighting will depend on what we want to do with our plants. If we want to induce flowering in a certain type of crop, for example, we will choose lamps that diffuse more red light. And if we want to keep them in the vegetative stage, we will go for a light that diffuses more blue-violet.
It goes without saying that the duration of the lighting has a strong impact on the results you want to achieve. It is difficult to give a precise number of hours, because everything depends on the needs of the plant in question. For example, if you want to induce flowering in a type of crop, or to start seedlings, you can light up to 16 hours per day! But as a general rule, we are not so much mistaken in providing a dozen hours of lighting / day to our plants and leaving them a rest period at night. Because, yes, they need it too.
That said, in most cases, gardeners want plants to have good overall growth and health. And to meet these needs, ideally, they should look for light that mimics the sun's spectrum as much as possible.
Incandescent bulbs
Let's not beat around the bush: this type of lighting is poor quality for your plants. We avoid it.
Compact fluorescent light bulbs (CFL)
This type of bulb is definitely better than an incandescent bulb for the needs of your plants. It is a type of lighting that can be interesting for example for seedlings and seedlings.
The spectrum of this type of bulb is usually either warm white or cool white, but the model offered by the company SunBlaster (which offers many good quality horticultural accessories including heat mats and thermostats), is 6,400K, which mimics sunlight. Sunblaster's compact fluorescent bulbs are also available at 2,700K, for gardeners who are more interested in inducing flowering. These bulbs are suitable for propagation and growth and are compatible with all standard sockets. They are available at 26 watts, which is equivalent to a 100 watt incandescent bulb. They provide 1700 lumens.
T5 fluorescent tubes
T5 horticultural fluorescent tubes (not your office neon, T12) generally provide a good spectrum (good quality of light) and are especially good for seedlings and seedlings. But generally, the lux number is low. Depending on the fluorescent tube model you choose, they can sometimes be bulky and fragile.
That said, SunBlaster has T5 fluorescent tubes with integrated reflectors that are already mounted on the ballasts and that you simply plug in. These fluorescent tubes are equipped with reflectors that allow a better diffusion of light and offer a full spectrum of light(Full Spectrum), which mimics sunlight quite well. They come in a variety of sizes (12" / 690 lumens, 18" / 1120 lumens, 24" / 1500 lumens, 36" / 2450 lumens, 48" / 3730 lumens) so they can fit into most gardening spaces.
The T5H0 is also available without a reflector, but the advantage of the reflector is that it spreads the light more widely over the plant's canopy, penetrating deeper into the plant's foliage, without consuming additional energy.
This is what they call the T5HO Nanotech Combo, which includes: the electronic ballast, a 6400K fluorescent, a 6' power cord with on/off switch, a 14" jumper cord, clips to hang the ballast or attach it to a flat surface.
The 6400K T5HO lamps have a spectral distribution with intensity peaks that fall between 435 nm and 615 nm, wavelengths suitable for photosynthesis. These lamps are ideal for propagation and long-term growth.
The company also offers replacement lamps (including 2700K T5HOs for gardeners who want to induce flowering instead), so there's no need to buy the whole kit again once equipped.
These lights radiate little heat, which is interesting unlike some previously offered models. The lights can therefore be placed 6 to 8 inches above the plant canopy, maximizing photosynthetic response and growth.
Horticultural LED lamp
LED horticultural lamps are currently the best options on the market, both in terms of lighting quality and energy savings. They produce less heat than fluorescent tubes, but more light, and the light they emit is continuous, which is not the case with many standard horticultural lamps that emit intermittently, although this is invisible to the naked eye. The fact that the light is continuous is even closer to sunlight and makes them more effective than other lights.
The Sunblast company offers a really great product with its LED lighting.
There is the LED Sunblaster Self Cooling, which comes in different sizes (12", 18", 24", 36", 48") and its main attraction is that it does not radiate unwanted heat.
And then there's the LED Sunblaster Prismatic lens, offered in the same dimensions (12" / 1600 lumens, 18" / 2500 lumens, 24" / 3400 lumens, 36" / 5000 lumens, 48" / 6700 lumens) (offers more than double the lumens as the T5HO), with the same appeal, but with a prismatic lens. This improvement causes light to pass through a prism that refracts and reflects light at a 90 degree beam angle rather than the 120 degree beam angle of older models. This ensures that more light reaches the canopy and significantly reduces losses. These LED strip lights are full spectrum with a maximum of 6400K, which is suitable for all horticultural uses: seed, general cultivation, propagation, microgreen production, etc. In terms of wavelengths, this is probably the type of lamp that provides the widest spectrum currently (between 400 nm and 700 nm). The improved light output of this model of horticultural lamp stimulates faster growth.
The Sunblaster Prismatic lens LED is also sold in kits: electronic ballast, 6400K fluorescent, 6' power cord with on/off switch, 14" jumper cord, clips for hanging the ballast or attaching to a flat surface.
Accessories offered by Sunblaster
The Sunblaster company offers several accessories and thus meets various needs that one could have during the installation of their various lamps, that it is to suspend them or to assemble the ballasts between them, which is rather interesting when one has a long surface to light:
Extension connectors for T5HO and LED ballast:
Suspension clips with rings for T5HO and LED:
Suspension clips for T5HO and LED:
So we can see that just because we don't have natural light in our home or we don't have enough lighting doesn't mean we have to deprive ourselves of having plants. There are plenty of solutions to fill the lighting gap, for different types of spaces, for different budgets. We just need to understand how lighting works to be able to choose what works best for us and our plants!