Plant lighting. Part 1: Why illuminate plants. Mysterious Lumens and Suites
- Part 1: Why illuminate plants. Mysterious Lumens and Suites
- Part 2: Lamps for lighting plants
- Part 3: Choosing a Lighting System
Indoor plants are very unlucky. They have to grow in a "cave", and everyone knows that plants do not grow in caves. The happiest plants get sunny window sills, but a similar arrangement with respect to light is, rather, an analogue of the undergrowth, under a tall tree, when the sun appears only either in the early morning or evening, and even that is scattered by foliage.
Perhaps the most unique case was my previous home when we lived on the eighteenth floor of a detached house. The windows were large, almost the entire wall, no other houses or trees blocked them, and my plants did not need to be illuminated at all, they managed to bloom 5-6 times a year (for example, bougainvilleas and callistemons). But, you understand, such a detached house is a rather rare occurrence.
Typically, plants really do not have enough light in room conditions, not only in winter but also in summer. No light - no development, no growth, no flowering.
This raises the question of the illumination of plants, which is aimed at compensating for the lack of lighting in the conditions of the room, the "cave".
Sometimes plants are grown completely without daylight, only at the expense of lamps, for example, in a room where there are no windows, or if the plants are far from the window.
Before you deal with plant lighting, you need to decide whether you intend to illuminate them or fully illuminate. If only to light up, then you can get by with fairly cheap fluorescent lamps, almost not caring about the spectrum of these lamps.
Lamps need to be installed over plants about 20 centimeters from the top sheet. In the future, it is necessary to provide for the possibility of moving the lamp or plant. I usually placed the lamps higher than expected, and I “pulled” the plants to the lamps, using pots turned upside down. Once the plants have grown, the pot stand can be replaced with a smaller one or removed.
Another question when you have already attached lamps: how many hours a day to light up? Tropical plants need 12-14 hours of daylight to fully develop. Then they will develop and bloom. So, you need to turn on the backlight a couple of hours before it gets light on the street, and turn it off a few hours after it gets dark.
With full artificial lighting of plants, one must also take into account the spectrum of lighting. Conventional lamps can not do here. If your plants do not see daylight, then it is necessary to install lamps with a special spectrum - for plants and / or aquariums.
It is very convenient to use a timer-relay when re-illumination or full illumination of plants. The most convenient way is dual-mode, that is, that the relay allows you to turn on in the morning for a couple of hours, and then in the evening.
Try to light up the plants and you will notice how much better they develop when they have enough light!
In this part, we will very briefly talk about the basic concepts that those who are trying to figure out in the huge variety of lamps for lighting plants are faced.
Lumens and suites are often a source of confusion. These values are units of measurement of luminous flux and illumination that need to be distinguished.
The electrical power of a lamp is measured in watts, and light flow ("Light power") - in lumens (Lm). The more lumens, the more light the lamp gives. The analogy with a hose for watering plants - the more the tap is open, the “wetter” everything will be around.
The luminous flux characterizes the light source, and light exposure - the surface on which light falls. By analogy with a hose - you need to know how much water gets to one point or another. It will depend on how long you need to water the plants in the garden.
Illumination is measured in lux (Lx). A light source with a luminous flux of 1 Lm, uniformly illuminating a surface of 1 square. m creates on it an illumination of 1 Lux.
Illumination on the surface is inversely proportional to the square of the distance from the lamp to the surface. If you move the lamp hanging above the plants at a height of half a meter, to a height of one meter from the plants, increasing the distance by half, then the illumination of the plants will decrease by four times. This must be remembered when you design a system for lighting plants.
Illumination on the surface depends on the angle at which this surface is illuminated. For example, the sun at summer noon, while high in the sky, creates several times more light on the surface of the earth than the sun, which hangs low above the horizon on a winter day.
If you use a spotlight to illuminate plants, try to keep the light perpendicular to the plants.
Spectrum and color
The color of the light emitted by the lamp is characterized by color temperature (CCT - Correlated Color Temp
erature). This is based on the principle that if heated, for example,
piece of metal, its color changes from red-orange to blue. The temperature of the heated metal, at which its color is closest to the color of the lamp, is called the color temperature of the lamp. It is measured in degrees Kelvin.
Another parameter of the lamp is the color rendering index (CRI - color rendering index). This parameter shows how close the colors of the illuminated objects are to true colors. This value has a value from zero to one hundred. For example, sodium lamps have a low color rendering, all objects under them seem to be the same color. New models of fluorescent lamps have a high CRI. Try to use lamps with a high CRI value to make your plants look more attractive. These two parameters are usually indicated on the labeling of fluorescent lamps. For example, / 735 - means a lamp with a value of CRI = 70-75, CCT = 3500K - a warm white lamp, / 960 - a lamp with CRI = 90, CCT = 6000K - a daylight lamp.
|2000||Low pressure sodium lamp (used for street lighting), CRI <10||Orange - Sunrise|
|2500||Uncoated high pressure sodium lamp (DNaT), CRI = 20-25||Yellow|
|3000-3500||Incandescent lamp, CRI = 100, CCT = 3000K|
Warm-white fluorescent lamp, CRI = 70-80
Halogen bulb, CRI = 100, CCT = 3500K
|4000-4500||Cold fluorescent lamp (cool-white), CRI = 70-90|
Metal halide lamp (metal halide), CRI = 70
|5000||Coated mercury lamp, CRI = 30-50||Light blue - midday sky|
|6000-6500||Daylight fluorescent lamp, CRI = 70-90|
Metal halide lamp (metal-halide, DRI), CRI = 70
Mercury Lamp (DRL) CRI = 15
As a result of the photosynthesis process occurring in plants, the energy of light is converted into the energy used by the plant. In the process of photosynthesis, the plant absorbs carbon dioxide and releases oxygen. Light is absorbed by various pigments in the plant, mainly chlorophyll. This pigment absorbs light in the blue and red parts of the spectrum.
In addition to photosynthesis, there are other processes in plants, on which the light of different parts of the spectrum exerts its influence. By selecting the spectrum, alternating the duration of the light and dark periods, one can accelerate or slow down the development of the plant, shorten the growing season, etc.
For example, pigments with a sensitivity peak in the red region of the spectrum are responsible for the development of the root system, fruit ripening, and flowering plants. To do this, greenhouses use sodium lamps, in which most of the radiation falls on the red region of the spectrum. Pigments with an absorption peak in the blue region are responsible for leaf development, plant growth, etc. Plants that grow with insufficient blue light, such as under an incandescent lamp, are taller - they stretch up to get more “blue light." The pigment, which is responsible for the orientation of the plant towards light, is also sensitive to blue rays.
An important conclusion follows from this: a lamp designed to illuminate plants should contain both red and blue colors.
Many manufacturers of fluorescent lamps offer lamps with a spectrum optimized for plants. They are better for plants than the usual fluorescent ones used to illuminate rooms. It makes sense to use such a lamp if you need to replace the old one. With the same power, a special lamp gives more “useful” light for plants. If you are installing a new system for lighting plants, then do not chase after these specialized lamps, which are much more expensive than conventional lamps. Install a more powerful lamp with a high color rendering coefficient (lamp marking - / 9 ..). In its spectrum there will be all the necessary components, and it will give much more light than a special lamp.
Special thanks to the staff of the site toptropicals.com for permission to publish the article on our resource.