Table of Contents
Do you know LED plant lighting how LED beads and spectrum to choose? Common parameters such as PAR，PPF, light intensity, and the type of LED beads used is crucial for optimizing plant growth.
Now let’s first understand the common parameters of LED plant lighting.
Common Parameters of LED Plant Lighting
PAR (Photosynthetic Active Radiation)
PAR is the abbreviation of Photosynthetic Active Radiation. Plants use a range of light wavelengths (400-700 nm) for photosynthesis. This is critical for accelerating the photosynthesis process required for plant development.
Measurement Units:
W/m²: Primarily in broader solar radiation research. Measure the effective radiation energy.
µmol/m²s: Used in studies focused on the effects of artificial light on plants. It represents the density of photons within the PAR range that fall on a given area per second.
PAR Spectrum vs. Visible Light Spectrum
What is the difference between the Photosynthetically Active Radiation (PAR) spectrum and the Visible Light Spectrum?
The Visible Light Spectrum is usually measured in lumens. The visible light ranges from about 400 nm to 700 nm. This range breaks down into the colors of light we see. From violet (400 nm) through blue, green, yellow, and orange to red (700 nm). Violet and blue light have shorter wavelengths (about 400-500 nm). However, red light has the longest wavelength in the visible light spectrum (about 700 nm), as shown in Figure 1.
Lumens quantify the brightness of light as seen by the human eye. As seen in the illustration Figure 2, the human eye is susceptible to green and yellow light (about 555 nm). Lumens are predominantly the center section of the visible light spectrum, to which the human eye is most sensitive.
The PAR spectrum is the range of light wavelengths that plants use for photosynthesis. It ranges from 400 nm to 700 nm and includes blue light (400-500 nm), green light (500-600 nm), and red light (600-700 nm).
PAR vs. Lumens
For assessing LED plant lighting, why is PAR a more accurate measurement indicator? Rather than lumens?
Light levels in greenhouses are measured in lux or lumens. These units are related to human vision. However, these units do not fully represent the spectrum of light that plants need to grow.
Human Vision vs. Plant Needs: The human eye has three types of receptors (S, M, L). Most sensitive to blue, green, and yellow light. Lux and lumen measurements reflect this sensitivity. Lux and lumen focus on the parts of the spectrum that humans see most clearly.
Photosynthetic Efficiency: Figure 2 shows that wavelengths corresponding to blue and red light, which are critical to plant photosynthesis, are not as apparent in lumen measurements. This highlights why PAR is a more accurate measurement for assessing plant growth light.
While lumens might help you understand how bright a light source looks to the human eye, PAR is a more accurate measure of light’s efficacy for plant development. Because it covers the whole range of light that plants may use for photosynthesis.
Absorption Curve of Human Eye vs. Absorption Curve of Plant
Figure 2, left, is the absorption curve of human eye. It illustrates the sensitivity of three types of cone cells in human eye, which are responsible for color vision.
Short wavelength, S cone cells are most sensitive to blue light (420-440 nm).
Medium wavelength, M cone cells are most sensitive to green light (534-555 nm).
Long wavelength, L cone cells are most sensitive to red light (564-580 nm).
The peaks of these curves represent the wavelengths of light that human eye is most sensitive to. Green and yellow light are the easiest for our vision to perceive.
Figure 2, right, is the absorption curve of plant. As it shown, the absorption spectra of key pigments in plants involved in photosynthesis.
Chlorophyll a and chlorophyll b, green curves, absorb light in the 430-460 nm blue and 640-680 nm red regions. Carotenoids , yellow curve, absorb light at 450-500 nm blue-green wavelengths. Phytochrome Pfr, red curve, absorbs light in the 660-730 nm far-red spectrum. These pigments are necessary for collecting light energy, which drives photosynthesis. The red and blue sections are especially essential.
Figure 2 depicts the contrast between how the human eye sees light and how plants absorb it for photosynthesis. The human eye is particularly sensitive to green and yellow light. This is why conventional light metrics like lux are based on these wavelengths. Plants, on the other hand, rely on blue and red light to produce chlorophyll and perform other functions. Thus, lux is insufficient to assess plant illumination.
In a short, whereas the human eye is most sensitive to green light, plants require a broader spectrum of light, particularly in the blue and red areas, for maximum development. This disparity has resulted in the introduction of PAR to better reflect plant demands.
PPF (Photosynthetic Photon Flux)
PPF is the total amount of photosynthetically active photons emitted by a light source per second in the 400-700 nm. Quantified in micromoles per second (µmol/s).
With PPF you can estimate how much light is required to illuminate a specific area for plant growth. For example, if you are growing strawberries in winter with a PPF requirement of 200 µmol/m²/s. Planting area is 10 meters wide by 6 meters long (60 square meters). Then the total PPF required is 6,000 µmol/s. If each LED grow light for plants provides 2,000 µmol/s, three lights are needed to cover the LED plant lighting area.
PPF Limitations:
PPF doesn’t tell how much light reaches the plants. How effectively light is distributed across the growing area also unclearly. Therefore, it’s important to ensure every light has sufficient PPF to cover your crops effectively.
PPF is critical for the output of grow lights for plants. But it does not provide information on the light’s wavelength or its distribution over the growing area. To fully understand lighting requirements, more detailed information is needed.
PPE (Photosynthetic Photon Efficacy)
PPE indicates the efficiency of a light source in converting electrical energy into photosynthetically active photons within the PAR. Expressed as µmol/s per watt (µmol/J). Determine the effectiveness of a light source in promoting photosynthesis relative to its power consumption.
PPE (Photosynthetic Photon Efficiency): Calculated as PPF divided by input power. PPE tells us how many micromoles of photons are produced for every joule of energy consumed. It indicates the efficiency of the fixture.
PPE measures how efficiently a fixture converts electrical energy into usable light for plants. A high PPE value indicates a more efficient fixture. It can provide more photons for photosynthesis using less power. This efficiency is critical to optimizing energy costs and ensuring that plants receive enough light to grow.
PPFD (Photosynthetic Photon Flux Density)
PPFD is the quantity of photons within the PAR that reach a specific area (measured in square meters) per second. The unit is µmol/m²s. PPFD is an important statistic for knowing how much light plants get. It measures how much usable light is available for photosynthesis at the plant canopy level.
The PPFD light map in Figure 4 depicts three distinct light mappings. Each represents a different height of the grow lights for plants:
Height: 12 inches
At this height, the light intensity is highest. The maximum PPFD value is 930 µmol/m²/s in the center of the grow space.
The light is mainly concentrated in the center. PPFD values decrease when move toward the edges.
This configuration is appropriate for plants that demand strong light intensity right beneath the light source.
Height: 14 inches
At 14 inches, the light is more evenly distributed. The maximum PPFD value is 719 µmol/m²/s in the center.
The light in the center is still the most intense. But the distribution is more even than at 12 inches. Cover a wider area with plenty of light.
Height: 18 inches
At 18 inches, the light is more evenly distributed. Maximum PPFD value is 499 µmol/m²/s in the center.
The PPFD values across the growing area are lower than at other heights. While the light evenly covers a larger area. It is ideal for larger grow spaces or plants that require lower light intensities.
Growers may use the PPFD light map to identify the ideal height to hang their grow lights for plants. It is based on the unique lighting requirements of plants. Higher PPFD values imply increased light intensity. This is useful for plants that demand more light. Lower PPFD values with more equal distribution are preferable for plants with a larger coverage or lower light requirements. Growers may pick the optimum height by comparing PPFD to get the perfect combination of light intensity and coverage area.
PPF vs. PPFD
PPF is a measurement of a fixture’s total light output. It accounts for all photons emitted.
In contrast, PPFD measures the actual light intensity in the exact location where the plants are placed. Figure 5 illustrates how spills or reflections can cause photons to be lost.Not all emitted light reaches the intended location. PPFD takes these losses into account and indicates the plant’s effective light level.
Essentially, PPF is a bigger idea. While PPFD gives a more practical assessment of plant development in terms of light in the growing environment.
Both measures can assist improve lighting configurations for plant development. Ensure that plants receive enough light where it counts the most.
Effects of Different Wavelengths on Plants
Comparison Between Plant Absorption Peak and Plant Light Spectrum
Figure 6 shows a comparison between the absorption peaks of plant pigments and the spectrum used in horticultural lighting.
- Effects of red and blue light:
For most leafy green plants, wavelengths centered around 660 nm (red light) and 450 nm (blue light) have the greatest impact on photosynthesis. These wavelengths correspond to the absorption maxima of chlorophylls a and b, which are required for plant development.
- Pr and Pfr (plant pigments):
Plant pigments are photosensitive pigments that absorb red and far-red light. Convert between two forms: Pr (absorbs red light) and Pfr (absorbs far-red light). These pigments influence germination and flowering of plants.
- Overlap of absorption peaks:
Chlorophyll a and chlorophyll b absorption peaks correspond to the red and blue light spectra. Plant pigments Pr and Pfr have similar sensitivity to red and far-red light.This overlap is valuable for designing effective grow lights for plants. Because it ensures that the light emitted is in the range that is most useful to the plants.
The effects of specific wavelengths of light, especially in the red and blue regions, on key plant pigments such as chlorophyll and phytochrome are closely related to optimizing the growth spectrum to support plant growth. Matching light wavelengths to plant needs maximizes photosynthesis and promotes healthy development.
Different Wavelengths of Light Quality Effects
Purple Light 395nm
395nm purple light grow lights for indoor plants promote the formation of anthocyanins in plants. Improve the coloration of flowers and fruit.
Inhibits the elongation of internodes beneath branches and leaves. Prevent excessive plant growth.
Increases the nutrient content and accumulation of organic matter in plants. Add better taste.
Blue Light 460nm
Chlorophyll a, chlorophyll b, and carotenoids have strong absorption capabilities. Promote the assimilation of nitrogen compounds and protein synthesis in plants.
460nm blue light grow lights for indoor plants promotes the morphological development. A significant role in the early stages of growth, and helps establish a well-developed root system.
Affects phototropism in plants, promotes the opening of stomata, and enhances the efficiency of photosynthesis.
Green Light 525nm
525nm green light grow lights for indoor plants have a relatively low absorption rate but play a certain role in photosynthesis.
It can penetrate the leaf canopy. Promote photosynthesis in the lower leaves.
Can be adjusted to complement red and blue light. Reduce visual pollution.
Red Light 660nm
In low light environments, the absorption rate of chlorophyll and plant phytochromes Pr/Pfr is high, and the efficiency of photosynthesis is improved, which is beneficial for promoting plant growth.
660nm red light grow lights for indoor plants promote the synthesis of organic compounds in plants. Lead to taller plants with larger leaves.
Red light, by regulating phytochromes, helps control the morphological development of plants.
Infrared Light 730nm
730nm infrared light indoor grow lights promote the conversion between plant phytochromes Pfr and Pr, inhibit flowering, and control the flowering period.
Using plant red light at 660 nm has a beneficial effect, enhancing the strength of photosynthesis.
Irradiation with far-red light avoids photomorphogenic responses and accelerates plant growth.
The Effect of Light Intensity on Plants
The intensity of PPFD affects the photosynthetic rate of plants. Within a certain range, below the light saturation point as Figure 12 shows, the higher the PPFD, the higher the photosynthetic rate, and the greater the plant yield.
Light Compensation Point: It is the light intensity at which the photosynthetic rate of a plant’s leaves equals the respiration rate. Result in a net photosynthetic rate of zero. The formation and consumption of organic matter are in balance. At this point, the light intensity is termed the light compensation point.
Light Saturation Point: This occurs when the light intensity reaches a certain level, beyond which an increase in light intensity does not lead to an increase in the photosynthetic rate. This phenomenon is known as the light saturation point.
Net Photosynthesis: The difference between the total amount of CO2 absorbed during photosynthesis and the amount released during respiration.
Total Photosynthesis: The total amount of CO2 absorbed during photosynthesis.
Light Intensity Design: The PPFD value is extremely important for plant growth. Do not overly focus on the spectrum or light quality design of LED plant lighting while neglecting the design of light intensity.
Table 1. Compensation Point and Light Saturation Point Comparison Table for Various Plants
| Plant Type | Light Compensation Point (μmol/m²s) | Light Saturation Point (μmol/m²s) |
|---|---|---|
| Watermelon | 53.1 | 1985 |
| Cucumber | 51 | 1421 |
| Green Pepper | 80 | 1719 |
| Eggplant | 50 | 1400 |
| Lettuce | 59.6 | 1360 |
| Strawberry | 90 | 1120 |
| Grapes | 70 | 1180 |
| Roses | 62 | 1200 |
| Orchid | 60 | 620 |
| Cactus | 80 | 325 |
| Succulents | 55 | 617 |
| Poinsettia | 58 | 749 |
| Liliaceae | 50 | 523 |
| Gardenia | 57 | 424 |
| African Violet | 45 | 417 |
| Food Grass | 50 | 410 |
| Indoor Ornamental | 45 | 360 |
| Lotus | 55 | 657 |
| Carrot | 49 | 506 |
| Hemp | 63 | 1600 |
The X-axis is light intensity. The Y-axis is CO2 exchange, where: CO2 absorption (positive values) indicates photosynthesis. CO2 release (negative values) indicates respiration.
Point A: Represents the state in darkness. Plant is only respiring. Lead to the release of CO2. This is where the plant does not get light, and hence photosynthesis does not occur.
Point B: The light compensation point. At this point, the light intensity is adequate to balance photosynthesis and respiration. The quantity of CO2 taken during photosynthesis equals the amount emitted through respiration. A net zero CO2 exchange.
Point C: Light saturation point. At this level of light intensity, photosynthesis reaches its maximum rate. Further increases light intensity do not lead to an increase in photosynthesis. The plant is operating at its full photosynthetic capacity.
Recommended Used Lamp Beads for LED Plant Lighting
High Parameter LED Plant Lighting Source
2835 White Light (High PPE) LED Beads for Indoor Grow Lights
| Product | Color | Φ(Lm) | VF(V) | IF(mA) | PPF(μmol/s) | PPE(μmol/J) |
|---|---|---|---|---|---|---|
| CH-2835F3NKC5 | 3000K | 36-38 | 2.6-2.8 | 60 | 0.46-0.48 | 3.0-3.2 |
| CH-2835F3NKSS | 3000K | 38-40 | 2.6-2.8 | 60 | 0.47-0.49 | 3.2-3.4 |
| CH-2835F1NKC5 | 5000K | 38-40 | 2.6-2.8 | 60 | 0.50-0.55 | 3.2-3.4 |
| CH-2835F1NKSS | 5000K | 40-42 | 2.6-2.8 | 60 | 0.55-0.60 | 3.4-3.6 |
3030 White Light (High PPE) LED Beads for Indoor Grow Lights
| Product | Color | Φ(lm) | VF(V) | IF(mA) | PPF(μmol/s) | PPE(μmol/J) |
|---|---|---|---|---|---|---|
| CH-3030F3NKC5 | 3000K | 36-38 | 2.6-2.8 | 60 | 0.46-0.48 | 3.0-3.2 |
| CH-3030F3NKS5 | 3000K | 38-40 | 2.6-2.8 | 60 | 0.47-0.49 | 3.2-3.4 |
| CH-3030F1NKC5 | 5000K | 38-40 | 2.6-2.8 | 60 | 0.50-0.55 | 3.2-3.4 |
| CH-3030F1NKS5 | 5000K | 40-42 | 2.6-2.8 | 60 | 0.55-0.60 | 3.4-3.6 |
3030 Plant Red (High PPE) LED Beads for Red Light Bulb LED Plant lighting
| Product | WLP | VF (V) | IF (mA) | PPF (μmol/s) | PPE (μmol/J) |
|---|---|---|---|---|---|
| CH-3030RNKL3 | 660nm | 1.8-2.0 | 300 | 1.8-2.1 | 3.4-3.6 |
| CH-3030RNKL6 | 660nm | 1.8-2.0 | 300 | 1.9-2.4 | 3.6-4.0 |
| CH-3030RNKG6 | 660nm | 1.8-2.0 | 300 | 2.2-2.6 | 4.2-4.4 |
| CH-3030RNKS8 | 660nm | 1.8-2.0 | 300 | 2.4-2.8 | 4.6-4.8 |
3535 Plant Red (High PPE) LED Beads for Red Light Bulb LED Plant lighting
| Product | WLP | VF (V) | IF (mA) | PPF (μmol/s) | PPE (μmol/J) |
|---|---|---|---|---|---|
| CH-3535RNKG9 | 660nm | 1.9-2.1 | 350 | 2.6-3.0 | 4.0-4.2 |
| CH-3535RNKL8 | 660nm | 1.9-2.1 | 350 | 2.7-3.2 | 4.2-4.4 |
| CH-3535RNKJ6 | 660nm | 1.8-2.0 | 350 | 2.8-3.3 | 4.6-4.8 |
| CH-3535RNKQ8 | 660nm | 1.8-2.0 | 350 | 3.0-3.5 | 4.8-5.0 |
5054 White Light (High PPE) LED Beads for Indoor Grow Lights
| Product | Color | CRI | VF(V) | IF(mA) | PPF(μmol/s) | PPE(μmol/J) |
|---|---|---|---|---|---|---|
| CH-5054F3NKC5 | 3000K | 80 | 5.4-5.6 | 200 | 3.0-3.2 | 2.8-3.0 |
| CH-5054F3NKS5 | 3000K | 80 | 5.4-5.6 | 200 | 3.1-3.3 | 2.9-3.1 |
| CH-5054F1NKC5 | 5000K | 80 | 5.4-5.6 | 200 | 3.1-3.3 | 2.9-3.1 |
| CH-5054F1NKS5 | 5000K | 80 | 5.4-5.6 | 200 | 3.2-3.4 | 3.0-3.2 |
5054 Plant Blue (High PPE) LED Beads for Plant Light Indoor
| Product | WLP | VF(V) | IF(mA) | PPF(μmol/s) | PPE(μmol/J) |
|---|---|---|---|---|---|
| CH-5054BNKC5 | 460nm | 5.4-5.6 | 200 | 3.0-3.2 | 2.9-3.1 |
| CH-5054BNKS5 | 460nm | 5.4-5.6 | 200 | 3.0-3.2 | 3.0-3.2 |
3030/3535 Purple light (high milliwatt) LED Beads for Plant Light Bulbs
| Product | WLP | VF(V) | IF(mA) | Φe(mW) |
|---|---|---|---|---|
| CH-3030VNKJ3 | 395nm | 3.2-3.4 | 300 | 200-230 |
| CH-3030VNKJ5 | 395nm | 3.2-3.4 | 300 | 230-260 |
| CH-3030VNKG3 | 395nm | 3.0-3.2 | 300 | 420-450 |
| CH-3535VNKG5 | 395nm | 3.2-3.4 | 700 | 750-800 |
Conventional LED Plant Lighting Source
2835 White Light (Cost-Effective PPE) LED Beads for Plant Light Indoor
| Product | Color | CRI | VF(V) | IF(mA) | PPF(μmol/s) | PPE(μmol/J) |
|---|---|---|---|---|---|---|
| CH-2835F3NKCA | 3000K | 80 | 2.6-2.8 | 60 | 0.44-0.46 | 2.7-2.9 |
| CH-2835F3NKS4 | 3000K | 80 | 2.6-2.8 | 60 | 0.45-0.47 | 2.7-2.9 |
| CH-2835F1NKCA | 5000K | 80 | 2.6-2.8 | 60 | 0.46-0.48 | 2.8-3.0 |
| CH-2835F1NKSS4 | 5000K | 80 | 2.6-2.8 | 60 | 0.46-0.48 | 2.8-3.0 |
3030 White Light (Cost-Effective PPE) LED Beads for Hydroponic Grow Lights
| Product | Color | CRI | VF(V) | IF(mA) | PPF(μmol/s) | PPE(μmol/J) |
|---|---|---|---|---|---|---|
| CH-3030F3NKC4 | 3000K | 80 | 2.6-2.8 | 60 | 0.44-0.46 | 2.7-2.9 |
| CH-3030F3NKS4 | 3000K | 80 | 2.6-2.8 | 60 | 0.45-0.47 | 2.7-2.9 |
| CH-3030F1NKC4 | 5000K | 80 | 2.6-2.8 | 60 | 0.44-0.46 | 2.8-3.0 |
| CH-3030F1NKS4 | 5000K | 80 | 2.6-2.8 | 60 | 0.46-0.48 | 2.8-3.0 |
2835/3030 Plant Red LED Beads for Plant Light Bulbs
| Product | WLP | VF(V) | IF(mA) | PPF(μmol/s) | PPE(μmol/J) |
|---|---|---|---|---|---|
| CH-2835RNKS2 | 660nm | 2.2-2.4 | 60 | 0.28-0.30 | 2.0-2.2 |
| CH-2835RNKL2 | 660nm | 2.2-2.4 | 150 | 0.75-0.95 | 2.2-2.4 |
| CH-3030RNKG3 | 660nm | 2.0-2.2 | 300 | 1.4-1.6 | 2.0-2.2 |
| CH-3030RNKL4 | 660nm | 1.9-2.1 | 300 | 1.5-1.7 | 2.4-2.6 |
2835/3030 Plant Blue LED Beads For Greenhouse Grow Lights
| Product | WLP | VF(V) | IF(mA) | PPF(μmol/s) | PPE(μmol/J) |
|---|---|---|---|---|---|
| CH-2835BNKQ1 | 450nm | 3.0-3.2 | 60 | 0.35-0.37 | 1.8-2.0 |
| CH-2835BNKS2 | 450nm | 3.0-3.2 | 150 | 0.36-0.38 | 2.1-2.3 |
| CH-3030BNKC4 | 450nm | 3.0-3.2 | 150 | 1.0-1.1 | 2.1-2.3 |
| CH-3030BNKC5 | 450nm | 3.0-3.2 | 300 | 1.8-2.0 | 2.2-2.4 |
Spectrum Recommendations For Different LED Plant Lighting
There is a spectral distribution for plant growth LEDs analysis. Present various spectral distribution graphs for different LED plant lighting products. Specifically designed for plant growth applications. Look at the Table 2 and Figure 13 a specific product, color, and intended application.
Table 2. Spectral Distribution for Plant Growth LEDs
| Product | Color | Application |
|---|---|---|
| CH-01 | White with a flush tint | Seedling Cultivation LED plant lighting |
| CH-04 | Slightly Cool White | Root Vegetables |
| CH-17 | Warm White | Leafy Vegetables, Fruits LED plant lighting |
| CH-12 | White | Plant Walls LED plant lighting |
| CH-02 | Pink-Purple | Supplementary Light for LeafY Vegetables and Flowers |
| CH-08 | Light Pink-Red | Flowers, Succulents |
| CH-19 | Slightly Warm White | Indoor Plant Supplementary Light |
| CH-06 | Cool White with a Hint of Pink | Supplementary Light for Leafy Vegetables and Succulents |
| CH-24 | Light Pink | Strawberry Supplementary Light |
| CH-09 | Pink-Red | Supplementary Light for Melons and Fruits |
| CH-S2 | Neutral White | General Purpose |
| CH-S1 | White | General Purpose |
LED plant lighting how LED beads and spectrum to choose? Are you clear now?
In summary, this blog introduces you to the professional terms of LED plant lighting: PAR, PPF, PPE, PPFD. Learn about different wavelengths of light quality effects. We also recommend lamp beads for LED plant lighting and the spectrum suitable for different plants.
Are you as enthusiastic about LED plant lighting as I am?
Are you looking to buy the best grow lights for indoor plants recently?
Do you know which is the best grow lights for seedlings?
How to choose between full spectrum led grow lights, uv light for plants, hydroponic grow lights, greenhouse grow lights or small grow light?
If you feel a headache and confusion about whatever your question is, please don’t hesitate to contact us. Our professional engineer team will help you.