I've grown before with a HPS for a few years and may soon have an opportunity to do a small personal grow, so I came to ask a question I couldn't find asked anywhere before, though I gathered some info about it:
What is the best spectrum of light for the highest quality buds, and what type of light(s) are best for producing it?
To define "quality", I'm talking about potency and quality of the high. I think this is more about the relative amounts of different types of psychoactive compounds than it is about THC percentage alone, or overall psychoactives as a percentage of total weight. If it was just about THC, then sativa and indica would have the same high, and if a strain had an ideal combination of psychoactives for a great high but low overall psychoactive content, then you could just smoke more of it.
I've read from many sources that X/Y/Z light source beats HPS on quality (though never on grams per watt) so lets go over the obvious options over what might be best:
CFL:
Produces very little heat and is available in low wattages so red and blue lamps can easily be combined even in very small grows, however the yields tend to be pretty low and the buds are usually "airy", lacking density.
CMH:
Produces less heat than HPS and has an extremely broad spectrum, wide enough that this bulb has a decent output of basically everything. The downsides are the decreased yield on account of the lower levels of red light than HPS, the bulbs are fairly expensive ($80 including shipping for a 400w to me), and they cannot be used with digital ballasts except specific, hard-to-find models.
Sulphur Plasma:
Full spectrum and very efficient, but very, very expensive. I have found very little written about the quality of buds produced under SP, which is no surprise given how rarely they're used.
Any one of/combination of the above plus supplemental red from HPS:
This seems plausible to me, although I'd like to stress that I'm talking solely about quality here. Just because a 600w HPS with a 400w CMH on each side of it would produce great quality and yield doesn't necessarily mean it would produce better quality than three 400w CMH lamps. My gut feeling is that while supplementing CMH with red would greatly increase yields without having a major effect on quality, it would decrease it slightly.
However, I could well be wrong. It could be that some supplemental red light is necessary for the best quality when using CMH as CMH may have less red than is ideal, this comes back to the question of what spectrum produces the best quality. If there was a good answer to that it would be relatively easy to work out how to produce it for given sized grow. Obviously what is "best" for quality is always going to be subjective to some degree but what I'm really hoping for is input from people who have tried doing grows with the same genetics, flowering period, nutrients etc but used different lighting so as to have good evidence to judge the different lighting methods by.
Full spectrum lighting plus supplemental UVB:
I have grown with supplemental UVB and noticed no difference in the high but the bud did seem to have more trichomes when I looked with a 100X microscope. I suspect that the UVB only increased the total amount of psychoactives on the buds, without changing the relative amounts of each psychoactive. I've only tried this with one strain though, so I'm not claiming to know this with certainty.
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Anyway, here's my plan as of now: Take a 2.5 x 2.5 tent (which would normally be fitted with a 250w HPS) and put in a 400w CMH. That would work out to 64w per sqft, which would probably be enough to compensate for the relatively low amount of red in the CMH spectrum. I am considering using a 2 x 2 tent instead, which would give me a massive 100w per sqft. This raises the question of whether light intensity has a significant effect on potency assuming spectrum is kept the same, and if anyone has done a couple of grows with all other factors except light intensity kept identical-e.g. upgrading from a 400w HPS to a 600w HPS-please tell us about your experience.
So to summarise:
What spectrum of light produces the highest quality buds? What, generally speaking, is the best way to achieve this spectrum using currently available grow lights?
What intensity of light is best? Does intensity only affect yield, of does it have an effect on quality too?
What is the best spectrum of light for the highest quality buds, and what type of light(s) are best for producing it?
To define "quality", I'm talking about potency and quality of the high. I think this is more about the relative amounts of different types of psychoactive compounds than it is about THC percentage alone, or overall psychoactives as a percentage of total weight. If it was just about THC, then sativa and indica would have the same high, and if a strain had an ideal combination of psychoactives for a great high but low overall psychoactive content, then you could just smoke more of it.
I've read from many sources that X/Y/Z light source beats HPS on quality (though never on grams per watt) so lets go over the obvious options over what might be best:
CFL:
Produces very little heat and is available in low wattages so red and blue lamps can easily be combined even in very small grows, however the yields tend to be pretty low and the buds are usually "airy", lacking density.
CMH:
Produces less heat than HPS and has an extremely broad spectrum, wide enough that this bulb has a decent output of basically everything. The downsides are the decreased yield on account of the lower levels of red light than HPS, the bulbs are fairly expensive ($80 including shipping for a 400w to me), and they cannot be used with digital ballasts except specific, hard-to-find models.
Sulphur Plasma:
Full spectrum and very efficient, but very, very expensive. I have found very little written about the quality of buds produced under SP, which is no surprise given how rarely they're used.
Any one of/combination of the above plus supplemental red from HPS:
This seems plausible to me, although I'd like to stress that I'm talking solely about quality here. Just because a 600w HPS with a 400w CMH on each side of it would produce great quality and yield doesn't necessarily mean it would produce better quality than three 400w CMH lamps. My gut feeling is that while supplementing CMH with red would greatly increase yields without having a major effect on quality, it would decrease it slightly.
However, I could well be wrong. It could be that some supplemental red light is necessary for the best quality when using CMH as CMH may have less red than is ideal, this comes back to the question of what spectrum produces the best quality. If there was a good answer to that it would be relatively easy to work out how to produce it for given sized grow. Obviously what is "best" for quality is always going to be subjective to some degree but what I'm really hoping for is input from people who have tried doing grows with the same genetics, flowering period, nutrients etc but used different lighting so as to have good evidence to judge the different lighting methods by.
Full spectrum lighting plus supplemental UVB:
I have grown with supplemental UVB and noticed no difference in the high but the bud did seem to have more trichomes when I looked with a 100X microscope. I suspect that the UVB only increased the total amount of psychoactives on the buds, without changing the relative amounts of each psychoactive. I've only tried this with one strain though, so I'm not claiming to know this with certainty.
______________________________
Anyway, here's my plan as of now: Take a 2.5 x 2.5 tent (which would normally be fitted with a 250w HPS) and put in a 400w CMH. That would work out to 64w per sqft, which would probably be enough to compensate for the relatively low amount of red in the CMH spectrum. I am considering using a 2 x 2 tent instead, which would give me a massive 100w per sqft. This raises the question of whether light intensity has a significant effect on potency assuming spectrum is kept the same, and if anyone has done a couple of grows with all other factors except light intensity kept identical-e.g. upgrading from a 400w HPS to a 600w HPS-please tell us about your experience.
So to summarise:
What spectrum of light produces the highest quality buds? What, generally speaking, is the best way to achieve this spectrum using currently available grow lights?
What intensity of light is best? Does intensity only affect yield, of does it have an effect on quality too?
