Interesting Article

[The Bard]

I posted this article in my journal a couple of months ago, but given the discussion here about different LED light set-ups, I thought I would repost it here. It is kind of "academic" in its language, but I thought the conclusion was interesting. The key take-away:

We find that yields increase linearly with light intensity up to at least 1500 μmols/ m2· s, which is at least twice the intensity that is most commonly used by cannabis growers. We also find no evidence that spectrum variations across our sample of specialty horticulture lights significantly affect yields versus general purpose broad-spectrum lights.

So in other words, as I understood it, lots and lots of light intensity, but the colour temperature doesn't have much impact.

Despite this, I am still looking at various specialty horticultural lights (LED, probably QBs), but thought all of you passionate lighting folks might be interested. Not willing to "take the risk" or test their theories myself (yet). LOL.

Here's the full article (free to download). BTW, the people who did the research operate a very large (legal) commercial cannabis grow op here in Canada.

The Profitability of Growing Cannabis Under High Intensity Light

The purpose of this study was to analyze the relationship between light intensity, cannabis yields, and profitability. We also look for evidence that spectrum d

papers.ssrn.com

 

[TorturedSoul]

We find that yields increase linearly with light intensity up to at least 1500 μmols/ m2· s, which is at least twice the intensity that is most commonly used by cannabis growers.

It also looks like they ran a constant 1,400 PPM of CO₂ during lights-on, well above the level in the average home grower's grow space. They wouldn't see those results (improved yield as light increases all the way to 1,500 μmols/ m2· s) if the CO₂ level was 400 PPM.

They should think seriously about increasing their lights-on temperature to 30°C, IMHO (at that level of light intensity and CO₂). I would expect their yields to go up even more.

 

[The Bard]

It also looks like they ran a constant 1,400 PPM of CO₂ during lights-on, well above the level in the average home grower's grow space. They wouldn't see those results (improved yield as light increases all the way to 1,500 μmols/ m2· s) if the CO₂ level was 400 PPM.

They should think seriously about increasing their lights-on temperature to 30°C, IMHO (at that level of light intensity and CO₂). I would expect their yields to go up even more.

Unfortunately, my set up/budget doesn't allow for PPFD that high, nor CO2. I was more interested in the light colour aspect. You should let them know about the temperature suggestion!

 

[TorturedSoul]

They'll figure it out the first time their industrial-sized a/c takes a vacation for three days and their plants take over the facility, lol.

The light colour aspect... I grew cannabis for years with HIDs, then someone came around and told me that the vast majority of HPS bulbs' output was in portions of the spectrum that plants couldn't benefit from. <SHRUGS> I just figured someone forgot to tell the plants that .

 

[thinkbetter12]

So, in flower, with a light with a veg and flower switch, this would say flip them both on. Yes?

 

[TorturedSoul]

Everybody does, yeah.

 

[thinkbetter12]

Cool! Thanks. Changed already. I guess I was just chicken.