LED Grow Lights Basics - For every indoor grower

Just as indoor growers are gaining in numbers, so are the LED grow lights in the market today. It can get overwhelming to pick the right one for your growing space and plants. This article focusses on the basics of LED Grow lights and what you MUST look for when choosing your grow light

Here are key things you need to look for when choosing your LED grow light.

Essentially here are LED grow lights explained!

What you need to know

Plants use light spectrum in the 400-700nm range in order to perform photosynthesis. A photon is a single particle of light, and could be of a variety of wavelengths. Photons that are capable of contributing to photosynthesis are considered a photosynthetic photon. Photons with wavelengths between 400 nm and 700 nm are hence called Photosynthetic Photons

What is PAR (Photosynthetic Active Radiation)?

PAR light is the wavelengths of light within the visible range of 400 to 700 nanometers (nm). PAR is the type of light plants need for photosynthesis. The amount of PAR light produced by the grow lights is important for growers.  Quantum sensors are the main instruments used to quantify the light intensity of horticulture lighting systems. These sensors work by using an optical filter to create a uniform sensitivity to PAR light.

What is PPF (Photosynthetic Photon Flux)?

As we established above, photosynthetic photons are the light photons that plants will use for photosynthesis. PPF is the amount of Photosynthetic photons the grow light produces. In other words, PPF measures the amount of PAR produced per second by that grow light. PPF is measured in μmol/s (micromoles per second). It is important to note that PPF is measure of how much PAR a light produces. It is not a measure of how much PAR actually falls on the surface of the plant. For that we need to measure the PPFD. 

What is PPFD (Photosynthetic Photon Flux Density)?

 PPFD measures the amount of PAR that the plant actually receives. It tells you the exact amount of photons that fall on the plant per square metre every second. PPFD is measured in μmol/m2/s. For that reason, it is important for buyers to note that PPFD measurements shared by grow light manufacturers should always come with Distance from the light source & Location and whether this is averaged over a certain area. PPFD varies at different heights and at different angles and is usually the strongest towards the centre area of the light source. 

What instruments can i use to measure PAR, PPF and PPFD?

Using quantum sensors and integrating spheres, you can effectively and accurate measure PAR, PPF and PPFD produced by a light source and received by the plant. 

This representation by Osram and their subsequent article are also great resources to understand grow light and PAR measurements. 

Photosynthetic light response curves chart | PPFD, Horticulture lighting metrics, How to measure PPF, PAR Light

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