Spectral Intensity Distribution For Common Grow Lights vs The Sun

[The Physicist]

Hi everyone,

I have not seen this anywhere so I figured I'd post my data. I measured the spectral intensity distribution of various grow light sources that many new growers use and compared it to sun light at noon in California. While I don't personally have a HPS/MH, that data has been around for over 40 years, google it. Note, spectrum measured with Ocean Optics HR2000+. By integrating the spectral intensity distribution with the measured Lux, one can calculate their exact PPFD/PAR. See the attached info below:


Sunlight:

T5 Tubes:

Full Spectrum Feit LED:

Cool CFL LED 100W Equivalent (Home Depot):

Optimized Side/Under Canopy Spectra:

Warm CFL LED equivalent 100W (Home Depot):

CMH 315W Phillips 3100k Spectra:

 

[The Physicist]

Good luck everyone!

 

[The Physicist]

(PDF) Photosynthetic response of Cannabis sativa L. to variations in photosynthetic photon flux densities, temperature and CO2 conditions

PDF | Effect of different photosynthetic photon flux densities (0, 500, 1000, 1500 and 2000 μmol m(-2)s(-1)), temperatures (20, 25, 30, 35 and 40 °C)... | Find, read and cite all the research you need on ResearchGate

www.researchgate.net

 

[Pepperhead]

Hi everyone,

I have not seen this anywhere so I figured I'd post my data. I measured the spectral intensity distribution of various grow light sources that many new growers use and compared it to sun light at noon in California. While I don't personally have a HPS/MH, that data has been around for over 40 years, google it. Note, spectrum measured with Ocean Optics HR2000+. By integrating the spectral intensity distribution with the measured Lux, one can calculate their exact PPFD/PAR. See the attached info below:


Sunlight:

T5 Tubes:

Full Spectrum Feit LED:

Cool CFL LED 100W Equivalent (Home Depot):

Optimized Side/Under Canopy Spectra:

Warm CFL LED equivalent 100W (Home Depot):

CMH 315W Phillips 3100k Spectra:

Thanks for the info

 

[The Physicist]

Effects of UV-B on terpenes and THC concentration

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www.readcube.com

 

[The Physicist]

Interaction of different UV bands on THC/Terpenes

UVR8 Chemical Profile Shaping in Cannabis — AgricUltra™ Advancements

The potency of high quality marijuana increases in direct ratio to the amount of UVB light it receives.

www.agricultra.com

 

[Bud]

Effects of UV-B on terpenes and THC concentration

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www.readcube.com

Thanks, informative and helpful, and a good read

 

[The Physicist]

Thanks! Hope it helped!

 

[parnelli]

Thanks for the data - nicely done and appreciate the posts - you obviously have the equipment to collect this data - I'm envious

 

[The Physicist]

Thanks for the data - nicely done and appreciate the posts - you obviously have the equipment to collect this data - I'm envious

No problem! Hope its helpful. To me its a nice to see what options there are for improving the grow. For example I didn’t actually think the warm LED CFL equivalents gave off so much NIR which helps the plants during flowering quite a bit. Learn something new everyday!

 

[parnelli]

Great to know - I have a similar CFL (125W - not sure if its labeled cool or warm) that I used in vegetation and early flowering. It's packed away and I can't get to it easily to see what type. Next time I'll use the CFL with the LED during flowering.

 

[The Physicist]

I’m going to be adding the very warm CFL LEDs and two UVA Bulbs in about a week to my flowering plants. Should boost both flower and thc and terpene density/growth so it will be interesting. Good luck!

 

[The Physicist]

Another great paper from 2018:

The Effect of Light Spectrum on the Morphology and Cannabinoid Content of Cannabis sativa L.

The Effect of Light Spectrum on the Morphology and Cannabinoid Content of Cannabis sativa L.

Cannabis sativa L. flowers are the main source of Δ-9-tetrahydrocannabinol (THC) used in medicine. One of the most important growth factors in cannabis cultivation is light; light quality, light intensity, and photoperiod play a big role in a successful growth protocol. The aim of the present...

www.karger.com

 

[parnelli]

Nice find! I'll stick with the LED's

 

[The Physicist]

I’m actually upgrading to the Hortilux CMH 315W. I’ll post the measured spectrum later tonight when the ladies wake up.

Turns out the Phillips Bulbs have a UV blocker, and the Hortilux does not. So the improved UVA from bulb switching is all I’ll need.

 

[Pepperhead]

Waiting to see as Iam using the Phillips bulb 315cmh currently

 

[The Physicist]

Bulb in hand, t-2hrs until ignition!

 

[The Physicist]

I’ll post the measured spectrum at that time, not limited like the box shows. Very excited to say the least.

 

[The Physicist]

Hortilux 315W 4100k CMH Spectrum:

Note the energy in the UVA band is more than 3x the Phillips 3100k. The energy in the 700-850nm range is comparable. Overall the Hortilux is the clearly better option as it provides a broader more smooth natural sun light spectrum.

 

[The Physicist]

The difference is visual too, the light appears slightly more yellow than the 3100k bulb even though its a 4100k, very interesting.