5 Key Parameters You Need to Know Before Choosing a Grow Light


Choosing right grow lights is the most chanllenging part for setting up a hydroponic or organic garden indoors system. Imagining how amazing it is by growing your plants from seedling to harvest even without any sunlight, no more weather changing conditions. Grow Lights can provide the light energy needed for your plant photosynthesis.

This post will investigate everything you need to know about selecting the best growing light system for your indoor growing needs.


1. Spectrum

Grow light spectrum refers to the electromagnetic wavelengths of light produced by a light source to promote plant growth.

For photosynthesis, plants use light in the PAR(photosynthetic active radiation) region of wavelengths (400nm-700nm) and includes red, blue and green wavebands, measured in nanometers (nm) .The growth of plants mostly depends on the red and blue light. The earliest led grow light all based on the spectrum of these two wavelengths. With in-depth research, it has been found that far-red light is closely related to the potential for yield and control growth. So Groplanner LED grow light have updated to targeted full-spectrum grow lights for increasing the yield and quality. 


Blue light Wavelengths (400 – 500 nm)

Blue light has a variety of important photomorphogenic roles in plants, including stomatal control (Schwartz and Zeiger, 1984), which affects water relations and CO2 exchange, stem elongation (Cosgrove, 1981), and phototropism (Blaauw and Blaauw-Jansen, 1970). Blue light also promotes other secondary metabolic compounds associated with improved flavor, aroma and taste. For example, blue light treatments have been shown to improve terpene retention in some varieties of cannabis. But a larger proportion of blue light has an inhibitory effect on cell elongation, which leads to shorter stems and thicker leaves.


Green Light Wavelengths (500–600 nm)

Absorption of green light is used to stimulate photosynthesis deep within the leaf and canopy profile, contributing to carbon gain and likely crop yield. In addition, green light also contributes to the array of signalling information available to leaves, resulting in developmental adaptation and immediate physiological responses. (Hayley L. Smith, Lorna McAusland, Erik H. Murchie, 2017)

Red Light Wavelengths (600–700 nm)


Red light in grow light is among the most effective wavebands at stimulating photosynthesis and promoting plant biomass growth. Red light regulates light morphogenesis by regulating phytochromes, which affects the differentiation and division of plant cells. This feature of red light on plants can help plants complete morphogenesis on the one hand, and can also effectively prevent overgrowth and improve the quality and output of crops.


Far-red Wavelengths(700 – 800 nm)

Far-red impacts on plant morphology and development, also affect the photosynthetic performance of the leaf. Due to the Emerson enhancement effect, the combination of red and far-red light may result in a higher photosynthetic rate compared to applying both wavelengths independently (Emerson et al., 1957; Pettai et al., 2005).

Groplanner have been reseraching about light affects both plant growth (photosynthesis) and plant development (morphology) for 9 years. We found that the difficulties in designing an optimum grow light system is to determine wavelengths essential for specific crops. So Groplanner focused on the proportion of blue light required for some specific plant (such as marijuana) growth as well as the optimum wavelength of red and the red/far-red ratio.


2. Photosynthetic Photon Flux (PPF)

The PPF or Photosynthetic Photon Flux is the total amount of light in the PAR zone that is produced by a light source each second. So PPF measures the “photosynthetically active photons emitted by a lighting system per second”. Expressed in μmol/second.

PPF describes the total amount of light emitted by a fixture. PPF measurements are taken in a device called an “integrating sphere” which measures all the photons produced by the fixture. However, even in an ideal set-ups, 10-15% of these photons will be lost to radiance or reflection. Choosing the right grow lights need according to your planting area and useable PPF.


3. Photosynthetic Photon Flux Density (PPFD)

PPFD describes the density of PAR photons at some specific spot (the place measured). As we explain above, there is a limit to the density of photons that plants can use. The maximum density of photons (PPFD) ultimately determines the maximum quantity of photons (PPF) that we can provide in a grow space. This stands for photosynthetic photon flux density and it does more than just measure the PPF, it also measures the surface area. So consider factors such as distance from the light source, a number of measurements that account for the average, and the minimum/maximum ratio before you buy. This is another key reason why you should work with Groplanner who can offer you relevant metrics and the right tools to fully benefit from Groplanner LED grow lights.


4. Wattage

This is the most common measure of grow lights intensity and is a measure of electricity (watt = amp x volt). This determines how much electricity you actually consume. Of course, when choosing a plant light, 'The greater the power, the better the yield' is not accurate . In the case of emitting the same photon density, the smaller the power, the less heat is dissipated, and the higher the light performance. What is misleading is that you need to know actual power draw, not LED wattage marked. For the reason of that, Groplanner LED grow lights are all dimmable. You can adjust the light brightness according to different stages to control the amount of photon density and reduce your energy consumption.


5. Uniformity

Uniformity refers to the grow lights' ability to provide even light distribution over your plant canopy. Poorly designed reflectors can create patterns of grow light with hot spots where more light is directed. Uniform light distribution provides consistent light levels to plants across the canopy. The fixture comparison image below shows how two different fixtures produce drastically different uniformity coverage results in the distribution from the same lamp. Uniformity can be measured using Photosynthetic Photon Flux Density (PPFD) and Photobiological Flux Density (PBFD). A perfectly uniform light will have a ratio of 1/1. The closer these ratios are to 1, the more uniform the product lights the canopy.


The above are the 5 parameters you need to know before buying a grow light. Please choose grow light according to your growing situation (planting area, planting type, plant stage, etc.). If you still have problems about purchasing a grow light, please contact us and we will provide you with the most professional advice.


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