Assessing LED grow lights… effectively

Oct 15, 2015 Comments Off on Assessing LED grow lights… effectively by

‘Dennis McCarthy’ reporting:

Those of us reporting on the dynamic solid state lighting industry have seen big developments recently, notably how the SSL grow light segment has been expanding.
This piece isn’t meant to be a stand in for a consumer’s report style story. The intent is to help those involved in LED grow light vetting do a better job. There is a process involved in LED grow light evaluations, the focus here is in the assessment itself. The article details the best practices used in product validation procedures and touches on approaches and equipment used in the endeavor.

One of the tangents of farming methodology hinges on how to effectively illuminate indoor crops. That’s the focus today – other factors like soil quality, humidity, pH temperature, CO2, nutrients are of course intrinsically important. Alas, they are topics for another day.
The grow light industry has had some steady incumbents: High pressure Sodium lights Metal Halides, PLASMA, fluorescents, and now LED technology. Going forward some of these (most) will be considered outdated or unavailable.
There have been inroads made in how pests are managed or eradicated, fertilizers are better, climate control and the distribution of products are similarly becoming refined.
Currently those of us in the grow light subset have seen a ramping up of production and deployment of SSL – some of it effective & some not so effective. That’s the crux of the story, discerning if a product does what is claimed. It recently got easier and more accurate. This is a good thing as the number of those buying LED grow lights is at an all time high.

So ARE grow lights ready for prime time? – some yes and some are not!

Many modern era horticultural concerns are investigating the wares compelling points.
Why would these firms be ready to invest in these grow lights?
>LEDs have the potential to save the growers some cash via their energy sipping traits >LEDs can provide red and blue hues of light or any light recipe a grower chooses.
>The control, mixing and tuning can be automated with sophistication as never before


MCOB 200 watt emitter


Analysis of MCOB Spectrum


Because of the stated factors, LEDs will have an increasingly important role as variations of horticulture lighting evolve. Whether in giant buildings or basement grows, the advancement of the product class is allowing those investing in such lights to see the rationale & benefits in their use.
Indeed, many sophisticated approaches and lights are in place and they are vindicating the decision makers’ call. Some of these refined approaches that take advantage of the lights’ characteristics have been validated and are increasing yields with every passing year. The concept is that their use has been proven. The current dilemma is assessing which items work as purported.

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How can a grow light buyer get some meaningful information about these new slew of grow lights? Most of the folks tasked with vetting them ARE learning to look for, the determination of what to discern has advanced. A far cry from when certain growers would just wing it. A new breed of growers knows that the illuminance coming from their LED grow lights needs to focus on what the plants- not humans need.
Today as would be LED grow light buyers go about their due diligence, they are becoming more deliberate and exacting. That change is no doubt propelled by the high cost of acquiring& deploying the new lights. So the choice has to be a good one.
So what are the erstwhile lamp buyers examining and measuring anyhow?
> Photosynthetically Active Radiation (PAR) which covers wavelengths from 400nm to
700 nm and is measured in PPFD. Photosynthetic Photon Flux Density some wavelengths outside PAR are considered important for quality & growth as well the plants circadian rhythms.
> Research has shown that the light intensity at the canopy is most critical- for plants the aforementioned PPFD and the metric of (yield) are critical… as is YPPFD It is one of the key determinants of the light’s worthiness as a grow light product.

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These measures of Photon Flux Density are the metrics that define light intensity. These assessments vary with distance between the light source and the canopy and since not all the photons have an equal role in plant growth there is a way of determining which part of the spectrum the photons originate at.
> The Spectral Power Distribution(SPD) is vital as it shows the lights’ chromatic characteristics as they radiate away from the light source. There are several accepted references against which SPD can be measured. These include Chlorophyll A and B Chlorophyll F, Beta Carotene, McCrees’ Action Spectrum and the Greman DIN specthese references assist in the evaluation of light sources.
> CCT (CT) are factors used in emulating sunlight’s varying hues- These temperatures are varied and are a part of the plants growth and end cycle activities. There are seasonal changes as well as daily variegation of these color temperatures which can and will affect yields.
> The life cycle of plants includes cloning, rooting, vegetative growth, then flowering/ fruiting. Light characteristics may be altered in each stage and these may vary by genus, species or strain.
Which tool of evaluation will be needed to determine these aspects? We won’t dwell on Lux meters (they measure lumens- light used by human eyes). Quantum meters are devices that can measure PAR – PPFD and they are essentially the right tool. But they are like a one trick pony – and they are real pricey.
For assessing grow lights, Spectrometers and Integrating spheres are the Platinum standard- but they are impractical for many as one can’t easily transport them – you have to bring the lights to a certifying facility. That approach is often a hassle.

There are new various makes in the form of handheld spectrometers, these integrate the main hardware involved in Chroma investigations- paired to a smart device.
I retain my affinity for the Lighting Passport which has over a dozen measures relevant to grow light performance. I’m impressed by it as both a lighting industry journalist and a SSL product validator / quality maven.


The Passport has the perfect companion for those grabbing the salient grow light data- an application that can detail, calculate, record, save and distribute the data. It can even keep the data in a diary form FOR GROWTH TRIALS. It can do comparative analysis on different crops or light performance traits.
The exclusive pairing of the Lighting Passport spectrometer paired with the Spectrum Genius Agricultural lighting (SGAL) app allows for the collection of key performance parameters for grow lights. I use the tandem and I have nothing but praise for its’ elegance and utility. The pairing is a must have for those vetting grow lights or for folks involved in documenting HORTICULTURAL lighting parameters. The LP can be used to validate claims, manufacturers specs, or to chronicle growth and success records. Nothing else even comes close to the LP and the SGAL app for those involved in the horticultural lighting product segment.
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Should you want to acquire one Email Les Kacev at or call 858.349.7499 for details. (He helped spec the SGAL app software and is the most knowledge Passport rep there is globally)
By way of disclosure the stories’ author Dennis McCarthy- United Business Media has a role as an ambassador for Assentek ( the Passports’ maker) LEDMetrics and the whole SSL industry –as an independent, unaffiliated, uncompensated advisor.
The lighting industry is progressing these days as it looks to advance best practices and the use of the Passport and the SGAL application fall in to that category.


About the author

15 years horticulture experience to draw from
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