What is plant grow light

Plant grow light Introduction

The plant growth lamp is an artificial light source, usually an electric light source, which stimulates plant growth by emitting an electromagnetic spectrum suitable for photosynthesis. Plant lights are used in applications that do not have natural light or require supplementary light. For example: in winter, when the possible daylight time may not be enough to achieve the desired plant growth, lights are used to extend the time the plants receive light. If plants don’t get enough light, they will stop growing

What is plant grow light?

Plant grow light Typical usage

Plant lights are used in indoor gardening, plant propagation, and food production, including indoor hydroponics and aquatic plants. Although most plant lights are used in industry, they can also be used in homes.

According to the inverse square law, the intensity of the light radiated by a point source (in this case a bulb) that reaches the surface is inversely proportional to the square of the distance from the surface to the source (if an object is twice as far away, it will only receive four One part of the light) This is a serious obstacle for indoor growers, and many techniques are used to use light as efficiently as possible. Therefore, reflectors are often used in lights to maximize light efficiency. The lamps or lamps are moved as close as possible so that they have the same illumination, and all light from the lamps falls on the plants instead of the surrounding area.

For example, incandescent lamps, fluorescent lamps, metal halide lamps (HID), and light-emitting diodes (LED). Today, the most widely used lamps in professional use are HID and fluorescent lamps. Indoor flower and vegetable growers usually use high-pressure sodium (HPS/SON) and metal halide (MH) HID lamps, but fluorescent lamps and LEDs replace metal halides due to their efficiency and economy.

Metal halide lamps are often used in the vegetative phase of plant growth because they emit a greater amount of blue and ultraviolet radiation. With the introduction of ceramic metal halide lighting and full-spectrum metal halide lighting, they are increasingly used as exclusive light sources in the growth stage of vegetative reproduction. The blue spectrum may induce a greater nutrient response in plants.

High-pressure sodium lamps are also used as a single light source throughout the vegetative and reproductive stages. Likewise, they can be used as a correction for full-spectrum lighting in the reproductive phase. The red spectrum may trigger a greater flowering response in plants. If you use a high-pressure sodium lamp as the vegetative period, the plants will grow slightly faster.

In recent years, LED indoor growth lamps can produce light of specific wavelengths. NASA has already tested the efficiency of increasing space food on the space station. The results show that plants are affected by light in the red, green, and blue parts of the visible spectrum.

Plant grow light Type

High intensity discharge (HID) lamp

Although fluorescent lamps were a common type of indoor growth lamp in the past, HID lamps are now the most popular. High-intensity discharge lamps have high lumen/watt efficiency. There are several different types of HID lamps, including mercury vapor, metal halide, high-pressure sodium, and conversion bulbs. Metal halide and HPS lamps produce some color spectrum somewhat similar to the sun and can be used to grow plants. Mercury vapor lamps are the first type of HIDs and are widely used in street lighting, but when it comes to indoor gardening, they have a relatively poor spectrum for plant growth, so they are mostly replaced by other types of HIDs for growing plants.

All HID growth lamps require ballasts to operate, and each ballast has a specific wattage. Popular HID power includes 150W, 250W, 400W, 600W and 1000W. Among all sizes, 600W HID lamps have the highest luminous efficiency, followed by 1000W, and 600W HPS has 7% more light than 1000W HPS.

Although all HID lamps use the same principle, different types of bulbs have different starting and voltage requirements, as well as different operating characteristics and physical shapes. Because such a bulb will not work properly unless a matching ballast is used, even if the bulb is installed. In addition to producing lower levels of light, mismatched bulbs and ballasts can stop working or even burn out immediately.


Learn more:Comparison of HID and LED grow lights

LED (Light Emitting Diode)

LED lights are composed of light-emitting diodes, usually in a housing with a radiator or a built-in fan. LED light-emitting lamps usually do not require a separate ballast and can be directly plugged into a standard power socket for direct use.

LED grow lights vary according to usage. It is known from the study of photomorphogenesis that green, red, far-red, and blue light spectra have an impact on root formation, plant growth, and flowering, but there are not enough scientific studies or field tests to test the specific color ratios recommended by LED grow lights. It has been shown that many plants will grow normally if given red and blue light. However, many studies have shown that red and blue light only provide the most cost-effective growth method and that plants grow better under light supplementing green.

The white LED grow light provides a full spectrum and is designed to imitate natural light and provide plants with a balanced spectrum of red, blue, and green. The spectrum used varies, but the white LED grow lights are designed to emit similar amounts of red and blue light, and then added green light will appear as white. White LED lights are usually used for supplementary lighting in homes and office spaces.

A large number of plant species have been evaluated in greenhouse trials to ensure that the plants have a higher quality in biomass and biochemical composition, even comparable to field conditions. Measure the plant performance of mint, basil, lentils, lettuce, cabbage, parsley, and carrots by assessing the health and vitality of plants and their success in promoting growth. Promote a large number of flowering of selected ornamental plants.

In the LED growth light test conducted by Philips Lighting, in order to find the best light formula for growing various vegetables in the greenhouse, they found that the following aspects of light affect plant growth photosynthesis and plant development morphology. The total light varies with time. Change which time of day, (spectrum), light direction, and light distribution on the plant. However, it is worth noting that in the tests between tomatoes, mini cucumbers, and sweet peppers, the best formulas for all plants are different, depending on the crop and region, so currently they must optimize the LEDs in the greenhouse based on the experiment. Lighting and errors. They have shown that LED light affects disease resistance, taste, and nutritional levels, but as of 2014, they have not found a practical way to use this information.

The diode design used for the initial LED light-emitting diode is usually 1/3 watt to 1 watt. However, now LED growth lamps usually use higher power diodes, such as 3 watts and 5-watt diodes. For highly compact areas, COB chips between 10 watts and 100 watts can be used. Due to heat dissipation, these chips are generally less efficient.

The LED grow light should keep the plant at least 12 inches (30 cm) away from the plant to prevent leaf burns.

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Fluorescent lamp

Fluorescent lamps have many form factors, including long, thin bulbs and smaller energy-saving lamps. The color temperature of fluorescent lamps ranges from 2700K to 10,000K. The luminous efficiency ranges from 30lm/W to 90lm/W.

Plant grow light Spectrum

Different growth lamps produce different spectra. Plant growth patterns can respond to the color spectrum of light. This process is completely separated from photosynthesis and is called photomorphogenesis.

Natural lighting has a high color temperature (about 5000-5800 K). The color of visible light changes according to the weather and the angle of the sun, and a specific amount of light (in lumens) stimulates photosynthesis. The distance from the sun has little effect on the quality and quantity of light in these seasons and the resulting seasonal changes in plant behavior. The axis of the earth is not perpendicular to the plane of the orbit around the sun. For half a year, the North Pole is tilted towards the sun, so the northern hemisphere is close to direct sunlight, while the southern hemisphere must travel through more atmosphere before reaching the surface of the earth. In the other half of the year, this is the opposite. There is no change in the color spectrum of the light radiated by the sun, only the quantity (more in summer and less in winter) and the quality of the entire light reaches the surface of the earth. Some complementary LED grow lights in vertical greenhouses only produce a combination of red and blue wavelengths. The color rendering index can compare the matching degree of light with the natural color of regular sunlight.

The ability of plants to absorb light varies with species and environment. However, the general measurement that affects the light quality of plants is the PAR value or photosynthetically active radiation.

There have been several experiments using LEDs to grow plants, and it has been shown that plants need red and blue light for healthy growth. It has been found in experiments that the leaves of plants grown only under red (660 nanometers) are deformed poorly, but adding a small amount of blue can make most plants grow normally.

Learn more: What is Grow Light Spectrum?

Gavita Pro 1700e LED Grow Light Spectrum
Helenor Compact 720W spectrum

Plant grow lights requirements

The specific needs of plants determine which kind of lighting is most suitable for optimal growth, and artificial light must imitate the natural light that plants are most suitable for. If a plant does not get enough light, it will not grow, regardless of other conditions. For example, Vegetables grow best in full sunlight and thrive indoors. They need the same high light level, while leaf plants (such as philodendron) grow in the shade and can grow normally with lower light levels.
The way the plant light is used depends on the growth stage of the plant. Generally speaking, it is recommended that the plants receive 16 hours of irradiation during the seedling/growth stage, with an 8-hour rest time; during the vegetative stage, they receive irradiation for 18 hours with a 6-hour rest period; in the flowering stage, they receive a 12-hour and 12-hour rest period.


In addition, many plants also require darkness and light cycles, and this effect is called the light cycle to trigger flowering. Therefore, the switch can turn the light on or off at the set time. The optimal photoperiod ratio depends on the type and type of plants, because some prefer long and short nights, while others prefer the opposite or medium day length.

When discussing plant development, the photoperiod is very important.

Plants that respond to photoperiod flowers may have facultative or specific responses. The part-time response means that a plant will eventually bloom, regardless of the photoperiod, the flower grows faster under a specific photoperiod. Professional response means that plants will only flower if they are grown under certain light conditions.

Photosynthetically active radiation (PAR)

Usually used to measure the brightness and lumens of light, but they are photometric units that measure the intensity of light perceived by the human eye

Horticultural Lighting Terms e1565035188206
Photosynthetically active radiation

The spectral level of light that can be used for photosynthesis is similar to, but not the same, as measured by lumens. Therefore, when measuring the amount of light for photosynthesis in plants, biologists usually measure the amount of photosynthetically active radiation (PAR) that the plant receives. PAR represents the spectral range of solar radiation from 400 to 700 nanometers, which generally corresponds to the spectral range that photosynthetic organisms can use in the process of photosynthesis.

Learn more: Reviews on 3 best seller 600W led grow lights

Learn more: Understanding Grow Light PAR, PPF, PPFD and PPE

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