The Secret of LED Grow Lights Uncovered- PAR, PPFD, PPF, and DLI

It’s just a matter of time before LED grow lights take over the indoor plant growing market. Ever since the arrival of these Light Emitting Diodes with their super cost cutting tendency and efficiency, the entire indoor playing field has changed. Measurements of Foot-candles, Lux, and Lumens are now outdated metrics for determining the light requirements of plants.

The indoor growers are now aware of PPFD, PPF, and PAR as the measuring units of light. As summer waves good bye, days are getting shorter, and the weather is becoming cooler, even you might be thinking of growing your own indoor plants. You will have to research before you start growing your indoor plants. You will need to learn and understand what various terms mean in this specific area.

The purpose of this article is to explain the main terms relating to your LED grow lights and correct the misunderstanding. Along with terminologies you should also know how science of LED grow light works and why they are the best choice when it comes to growing indoor plants and vegetables.

For happy indoor growing with reduced electricity consumption with greener, and natural plants read below to learn about LED terminology

What Does PAR Mean?

Photosynthetic Active Radiation is a term used for defining the intensity of LED grow lights. Photosynthesis is the process by which plants convert light into chemical energy. PAR is not a measurement like inches, feet, or kilos. More precisely PAR defines the type of light that supports photosynthesis in plants.

Different types of light are defined by their “wavelengths”. A portion of the light spectrum is visible to the human eye (e.g. candle light) and another portion is not visible (e.g. infrared). Where light in specific is defined as electromagnetic radiation, the different wavelengths of various types of light make up the electromagnetic radiation spectrum.

The spectrum created by these different wavelengths includes radio, infrared, x-rays, and lights we see such as LED red or blue light and sunlight. The light used by plants for photosynthesis contains a portion of the visible spectrum and portions which are not visible to the human eye such as infrared and ultraviolet light.

Here, the most important thing for you to understand is that PAR does not measure light; instead it is the part of light that is required by the plants for photosynthesis. So, most important is the PPFD, PPF, and DLI. When you’re picking a grow light for your plants for promoting and triggering photosynthesis-remember to look for these factors:

• How much light is produced by the grow lights
• What part of the light produced by the grow lights is available to the plants?
• What is the amount of light received by plants during photoperiod?

Dorm Grow G8LED grow lights are designed with a spectrum that is optimized for indoor plant photosynthesis. The spectrum of these lights includes the necessary portions of the visible light spectrum along with far-red and non-visible ultraviolet light. Maximizing photynthesis is accomplished by eliminating any wasted wavelengths of light, such as green. For example, the color green is reflected by plants and does not contribute to their energy production through photosynthesis, so including the green wavelengths of light in a grow light diminish their efficiency in growing healthy plants.

The Measuring Metrics:

Photosynthetic Photon Flux (PPF) –

PPF is the first measurement unit that measures the total amount of light produced by light source every second. Alternatively, PPF determines the amount of PAR emitted by the light source per second. PPF is measured in “micromoles per second” and a very technical way of defining this unit is photosythetically active photons emitted by a lighting system per second. PPF is expressed in μmol/second (micromoles per second).

Photosynthetic Photon Flux Density (PPFD) –

The amount of light reaching the plant is measured by the PPFD. PPFD is defined as the number of photosynthetically active photons falling on a surface every second. PPFD is measured in μmol//m2/s (micromoles per square meter per second).

ay Light Integral (DLI) –

DLI is the third measuring unit that measures the total amount of light reaching the plant every day. DLI is the total number of photons reaching plants during daily photoperiod, which means the daily dose of energy the plant receives. DLI is measured in mol/m2/d (moles of photons per square meter per day).

The photoperiod, or time of exposure to light will need to be greater if the DLI is delivered with a lower PPF. DLI can be though of the total amount of rain falling during a storm as opposed to the rate of rain falling. A lighting system set up for an indoor plant growth starts with determining the required DLI.

Moles –

This measurement is for the large number of photons in the visible light. This number is so huge that no measuring metric is enough for expressing it in normal numbers, so two units are used by scientists- Mole is equal to Avogadro’s number while micromole is millionth of a mole.

Summing It Up:

The total amount of light delivered by light fixtures varies as every lighting system and indoor tent is different with a great number of factors affecting the light reaching the plants. PAR, PPF, PPFD, and DLI are useful metrics to measure the growing ability of grow lights, namely LED Grow lights.

Laura Ashley

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