LED vs HPS and Indoor vs. Greenhouse Growing - looking for add'l feedback

[timbeallnd]

My main background is growing in greenhouse (hydroponic tomato and also in soil for cannabis). Previously we grew around 2.0" to 2.5" of growth per 24 hour day/period in our greenhouses in Colorado (May high light) without CO2 augmentation. Our greenhouses (diffused sunlight) even during May had 24 hour supplemental HPS light. We yielded on high producing strains around 1.75-1.9 lbs per plant of dried bud with 6 weeks of Veg (flower averaged 8-9 wks). Roughly speaking the plants received around 65 mols/day (inside the greenhouse measurement at canopy), of which 30.5 mols/day was just Red/Blue light. CO2 ppm averaged around 375-450 ppm.

I've been doing a new growing trial for an LED company out of MN that produces a new flexible panel light that gives off very little heat, and one of their products in essence is 5% white/green, 10% far red, 70% red, and 15% blue. Quite honestly I had some initial problems because I absolutely hammered the seedlings with 880 umol of this light over a 24/0 period and reached over accumulation. This basically produced 76 mols/day of primarily only Red/Blue. The plants reacted negatively. I scaled it back (dimmers on the led) and also went to a 18/6 period and put on around 46 mols/day of just Red/Blue which recovered the plants and grew them healthy but only 1"-1.5" per day. Recently I added another White light LED (sunlight spectrum) to the tent and left on the white light 24/0 with the Red/Blue LED's on the same 18/6. Now putting on 80 mols/day total, with 50 mols/day of Red/Blue. I'm back up to 2"-2.5" of growth per 24 hours. There could be some drop off caused by genetics in growth (growing Pineapple Crush and White Diesel now, vs. Bruce Banner/Sage and Blue Dream in greenhouse). The grow tent is averaging about 500 ppm of CO2 (purposely keeping it similar to the previous greenhouse conditions to try and figure out optimal light).

Temperature, soil, humidity, fertilizer is all the same. Does anyone else have any kind of similar knowledge/results? Where to maximize growth they need to add White light that is relatively in-efficient for growth and electricity? My initial thought is that I need to add the white light to possibly increase the carotenoid harvesting of excess oxygen from the plant to attain max growth - thus preventing too much photo-respiration?

Or am the results/growing information I'm seeing currently maybe just reflective of age of youngs plants or genetics? Anyone else pushing 2.5" of daily growth just adding primarily Red/Blue light, without much White? Hydroponic doesn't count I know I can grow faster with it. Just prefer the taste of compost ammended peat/perlite soil.

 

[freemanjack]

My main background is growing in greenhouse (hydroponic tomato and also in soil for cannabis). Previously we grew around 2.0" to 2.5" of growth per 24 hour day/period in our greenhouses in Colorado (May high light) without CO2 augmentation. Our greenhouses (diffused sunlight) even during May had 24 hour supplemental HPS light. We yielded on high producing strains around 1.75-1.9 lbs per plant of dried bud with 6 weeks of Veg (flower averaged 8-9 wks). Roughly speaking the plants received around 65 mols/day (inside the greenhouse measurement at canopy), of which 30.5 mols/day was just Red/Blue light. CO2 ppm averaged around 375-450 ppm.

I've been doing a new growing trial for an LED company out of MN that produces a new flexible panel light that gives off very little heat, and one of their products in essence is 5% white/green, 10% far red, 70% red, and 15% blue. Quite honestly I had some initial problems because I absolutely hammered the seedlings with 880 umol of this light over a 24/0 period and reached over accumulation. This basically produced 76 mols/day of primarily only Red/Blue. The plants reacted negatively. I scaled it back (dimmers on the led) and also went to a 18/6 period and put on around 46 mols/day of just Red/Blue which recovered the plants and grew them healthy but only 1"-1.5" per day. Recently I added another White light LED (sunlight spectrum) to the tent and left on the white light 24/0 with the Red/Blue LED's on the same 18/6. Now putting on 80 mols/day total, with 50 mols/day of Red/Blue. I'm back up to 2"-2.5" of growth per 24 hours. There could be some drop off caused by genetics in growth (growing Pineapple Crush and White Diesel now, vs. Bruce Banner/Sage and Blue Dream in greenhouse). The grow tent is averaging about 500 ppm of CO2 (purposely keeping it similar to the previous greenhouse conditions to try and figure out optimal light).

Temperature, soil, humidity, fertilizer is all the same. Does anyone else have any kind of similar knowledge/results? Where to maximize growth they need to add White light that is relatively in-efficient for growth and electricity? My initial thought is that I need to add the white light to possibly increase the carotenoid harvesting of excess oxygen from the plant to attain max growth - thus preventing too much photo-respiration?

Or am the results/growing information I'm seeing currently maybe just reflective of age of youngs plants or genetics? Anyone else pushing 2.5" of daily growth just adding primarily Red/Blue light, without much White? Hydroponic doesn't count I know I can grow faster with it. Just prefer the taste of compost ammended peat/perlite soil.

Plants need sunlight or its nearest equivalent, on wot planet did blurple ever shine down on?? plants DO NOT need single colour light, this comes from poorly conducted experiments where leaves were blendered to a soup then lit with single frequencies of light and the resulting sugar content measured. Can you see anything wrong with that model?? How to grow more weed of better quality? replicate the natural growing ideal and let the plants do planty things. It ain't rocket surgery you know!
oh and LED vs HPS? entirely depends on which led and which hps, all leds are created equal but white leds are more equal than shite blurple, full stop!

 

[wietefras]

Plants need sunlight or its nearest equivalent

That's simply not true.

 

[CobKits]

I scaled it back (dimmers on the led) and also went to a 18/6 period and put on around 46 mols/day of just Red/Blue which recovered the plants and grew them healthy but only 1"-1.5" per day.

do you have any other way of quantifying growth other than height? targeted LED spectrums will definitely create shorter bushier branchier plants than sunlight

maybe you should be measuring leaf mass or leaf area or something

Temperature, soil, humidity, fertilizer is all the same

you should be running hotter with LED than you do with sunlight/HID/ fluorescent to compensate for lower leaf temp due to lack of IR. keeping atmospheric condtions the same will result in slower growth on the LED side due to lower metabolism due to lower leaf temps. +5-10F is recommended.

at very agressive light levels under temps too low you will see uptake issues with CA and Mg as these depend on respiration to draw them up, and with LED is kinda out of whack with how the plants evolved. correctable by raising temps or supplementing more of these nutes (or a combination of both)

Where to maximize growth they need to add White light that is relatively in-efficient for growth and electricity?

phosphor white is highly efficient, its almost a perfect match to mccree absorbance curve

 

[freemanjack]

That's simply not true.

Sorry, my mistake, plants happily grow in the dark! we should be doing everything we can to exclude all natural light or any near equivalent!

 

[OneHitDone]

do you have any other way of quantifying growth other than height? targeted LED spectrums will definitely create shorter bushier branchier plants than sunlight

maybe you should be measuring leaf mass or leaf area or something


you should be running hotter with LED than you do with sunlight/HID/ fluorescent to compensate for lower leaf temp due to lack of IR. keeping atmospheric condtions the same will result in slower growth on the LED side due to lower metabolism due to lower leaf temps. +5-10F is recommended.

at very agressive light levels under temps too low you will see uptake issues with CA and Mg as these depend on respiration to draw them up, and with LED is kinda out of whack with how the plants evolved. correctable by raising temps or supplementing more of these nutes (or a combination of both)


phosphor white is highly efficient, its almost a perfect match to mccree absorbance curve

 

[timbeallnd]

Okay. Jeez you guys are passionate Right now I'm running about 80% red/blue and achieving the same max growth rate i can get with sunlight. Basically proves that yes - we need Yellow/Green in addition to Red/Blue to hit the max growth rates. However I wouldn't agree that true sunlight spectrum which is more White (Yellow/Green) then Red and Blue is what is required. Possibly one of the posters is correct about increasing heat - something to try on a different trial. I'm averaging around 70-72 temp (sunlight only 6 hr) and 80-82 temp (all lights on). Right now I would say that it is possible to prove that LED is potentially more efficient with targeted spectrum than sunlight (umol of light to mass growth). What was really interesting though - was that I couldn't achieve the max growth rates without adding enough of the green/yellow light. FYI - zero issues with Ca/Mg uptake issues. l'm using a Cal/Mag feed. Without having enough Green/Yellow - I was bleaching the plants out. Now I'm hitting them with 30% more light - and no issues from bleaching. I think without the yellow/green carotenoids harvesting out the excess oxygen bi-product inside the plant - they weren't accomplishing true respiration, and instead going to photo-respiration.

I repeated the trial a couple of times. I turned down the white light (sunlight) to the dimmed 30% setting, the plants weren't harmed, but they lost their high productivity growth rate. I turned the white (sunlight) back to full and I again hit the 2" growth rate. I attached a couple of pics from 12 days earlier (after I had bleached out the plants), then also 1 week ago (before natural sunlight yellow/green), and then today after having 20% of natural sunlight spectrum added for 4 days.

 

[wietefras]

Sorry, my mistake, plants happily grow in the dark! we should be doing everything we can to exclude all natural light or any near equivalent!

Yeah super funny, pretending that you are that stupid.

Anyway, you said: "Plants need sunlight or its nearest equivalent". That's just dumb bullshit. They do fine on wildly different spectral distributions.