Does this mean a gram a watt per plant or per room or for each light? a friend told me I wasn’t really growing efficiently unless I was harvesting at least a gram per watt. They’re really almost seems to be too many variables to even judge that on like how far apart your plants are spaced or how higher lights may be from your plants? Can anyone explain exactly how that’s supposed to work plz
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I’ve never got 1 gram per watt. So I don’t buy into this at all. Now when these 3 plants finish maybe over 1 gram per watt due to them being massive plants.
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I wouldn’t worry about it. Tease your buddy and tell them you upgraded to DIY LED and are hitting 2.2 grams per watt.
Grams per watt is a flawed measurement of success. He’s talking about stated wattage draw of just lighting which ignores all the environmental control costs. It also doesn’t account for light cycle.
A better measure is grams per kWh, and nobody takes the time to measure that.
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Sometimes I hit 1g/watt, sometimes I don’t. Since I’m not pumping out massive amounts of weed, and I’m not too concerned with a few more $$$, it doesn’t really matter to me.
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I could connect my meter and find out… 
Grams per watt, no matter the cost, still cheaper than the expensary.
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I have a device that distinguishes between different appliances from the panel. Haven’t installed it yet. That’s a few hundred most people won’t spend. A Kill -O- Watt Meter or two would do the trick.
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Haha. Pun intended?
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the number you are looking for is g/watt/m²
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@KeystoneCops I have one that can be left plugged in safely. I use only one outlet so I probably could. Scared to find out though. Lol.
@MidwestGuy yes it was. lol
Tell your friend high per gram is far more important than grams per watt. See if he figures it out.
(Quality over quantity)
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I think a more appropriate way to measure this is grams per capital cost after depreciation.
Original investment into lights, fans and all the other goodies, taking into account eventual replacement costs, that includes lights, fert, soil… really everything down to panda poly and cleaning agents. Then uou have seed costs, losses to males if using reg seed?
Now we get into electricty to light and heat or cool, blow air around, vent, maybe air pumps or water pumps? As you can see the actual cost per gram is much higher than a simple watt per gram ratio. I find the watt per gram thing meaningless in the grand scheme of things. Not to mention a gram of shitty pot is not worth a watt of energy!
That was meant for the OP but it still applies.
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We’re of the same mind. There’s also an opportunity cost; Could the space be used for something else? That may seem small, but if you’re in an expensive housing market you oughta add that to the balance sheet.
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Gram /per watt… hmmm. Well since most of us do this for Fun, I think we should measure success by
Enjoyment /per gram cuz nothing beats enjoying your own hard work 
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I use gram per watt as a guide. It lets me know if my feeding regime is dialed in, the health of my plants, if my environment is dialed in and I have my lighting dialed in. I’m sure there is more It tells me. Is it flawed sure but it’s easy. My kill-o-watt tells me my lighting watt drawing 285 watts. If I get 285 or more grams dried the I did good. If not I look to see what can be improved. Even if I hit my gram/watt I’m still looking for improvements, to me each grow is a new experiment. A gram/watt is an easy measurement to judge each my most recent grow against past efforts.
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I suppose there may be a algebraic formula to figure out the opportune time to switch 12/12 that would depend on the strain, that would do a cost analysis with all the variables, taking into consideration veg to flower ratio over time vs yield. Some plants yield more smaller over time than bigger plants. I think outdoor the yoeld ratio is bigger because the distance from the light doesnt matter. Indoors it really matters and large plants dont benefit from the light fixture lower down.
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No time factor in there. So still not valid. I can grow a pound of weed under 200 watts of light if I have a year to do it. So is that a valid measure? No. Lighting demand changes over time as well and this figure does not take into account all of the variables that are required to grow good cannabis.
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that is true. I always calculate 8 weeks, for simplicity and because thats what most of my strains take. But you are absolutely right. Its not a relevant number anyways… only for myself, to get a good idea of how efficient I am.
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Man i love this forum lol everyone has great insight. I do have DIY lighting I have eight qb120 4 + 3000 k 4 + 4000 k my buddy however is a fan of the blurple light so that’s probably got something to do with it lol I think I will pick up a water meter just to see what I’m pulling from the wall thanks everyone
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