1 kilo per light - or why gm/watt suck!

1 kilo per light is easy with hydro/aero, and most importantly, a scrog screen in a small tent. Ive had well over a kilo with C99, Blue Dream, @ReikoX 's Ghost Toof #2xSBR, and @Sebring Dragon Tongue.

Actually, just a hair under 3 kilos with three of the Ghost Toof plants, and around 2 kilos with a single C99 plant, and about 1.5 or so with three of the Blue Dream, and just over 1 kilo with one Dragon Tongue.

The fixture is a 320 watt DIY LED with SolStrips from @Baudelaire

The key is the scrog screen and LST more than the strain.


I have been growing DWC for over 20 years almost exclusively, but only 2 or 3 plants at a time for the last 10 years due to space constraints. Got 17 ounces from 2 SoF Adventure Mix under a 400 watt hps.

Just getting started on what will be a 6 bucket RDWC scrog under a SF 4000 led in a 4’x4’ tent. First time growing with led.


I’m not here to dump a load in anyone’s cornflakes…heh heh but…surely you can see I am studying just that, the fact the strain makes all the difference in the world. Read that hash making thread I posted in advanced techniques. I operate on a different tech where I don’t rely on myself to see how the plant affects my mind, instead it’s empirical. lol, I don’t expect you to be like worshipping my data or something… just something to think about when you are wondering if that bud is actually good or just psychogenic. I promise I’m not someone who will be like “they said three kilos, fuck you buddy!” or some other conversation terminating garbage.


I’m sorry, that’s 3 KILOS (6 pounds) from a 320 watt fixture??? I’ve never heard of anyone ever yielding anything close to that in my almost 20 years of growing. 3lbs from a 1000W light is generally considered a very, very good yield…


heh heh I was going to get into the substantiation phase a little later on.

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Kind of hard to prove long distance. If you guys have been following my grows a all, you know I am not shy about posting failures and screw ups and stupid mistakes right along with the good stuff.

Im too sore and stoned to look up the links at the moment, but if you really want to know - check out the final posts in my last three or four aero grows for the harvest details and pics of the buds, etc.

If not, thats ok too :slight_smile:

Like I said - its not the light, or the strain - its the growing technique more than anything, and good use of a scrog screen is the key.

Focusing on the light fixture as the be all end all of growing is not beneficial. Especially using grams/watt. Grams/watt is a 100% meaningless number that tells you nothing.

Sorry. Im not feeling well and got a little carried away.


Trying to talk people out of using grams/watt, or even getting them to understand why it isnt valid, isnt easy. I know. Ive been trying to do that for a while now with little to no success. Its been in use so long, everyone just assumes is has to be good. Id bet at this stage maybe 90% of the growers on this board learned about grams/watt on their first grow. Plus, its in a video so it must be true!

Here is a different way to look at it that may be easier to understand why trying to rate grow yields based on light fixtures or watts isnt valid.

I have a single 320 watt fixture in a 7.3 sq ft tent. Lets start with one of my smaller yields on my most recent grow - 1156 grams. Just to make the math easier, lets call it 300 watts, and 7 sq ft and 1000 grams.

Now imagine I make that single fixture twice as wide and with two times the elements, so its now a 600 watt single fixture. But its twice as wide so its now covering 14 sq ft. Is there any reason not to expect to get 2000 grams now?

Grow #1 has a single fixture and gets 1kg.
Grow #2 has a single fixture and gets 2 kg.

There is no reason why this cant keep going until you have a single 3000 watt fixture over a large area yielding 10,000 gms = 10kg on a SINGLE fixture.

You can ignore the rest of this post unless you really want to hear why Gm/Watt is also meaningless number just like gms/fixture :wink:

Grams per watt is almost the same thing except that WATTS is the fallacy instead of the number of fixtures.

Take that C99 grow I was talking about earlier. I got around 2 kg off that single 320 watt fixture. Thats a hard to believe, whopping, amazing 6.25 grams/watt!!! How you ask??? “Time” is the answer.

I’ll let you do the math on the over 3kg yield I had from the same 320 watts.

That grow was over 5 months long. I spent much longer vegging that plant than any other I have done so far. That allowed me to grow a tree of a single plant. Combine that with a lot of scrog training, and aeroponics and there you go.

My point is, grams/watt is meaningless unless you include the length of the grow AND either the number of plants or the sq ft of the space. And, watts is still almost completely irrelevant.

A few watts one way or the other has virtually no effect on yield. Plus, how do you measure it?

For example, my fixture is rated at 320 watts, but I almost never turn it up to 320. During the early growth, the light is turned down under 100 watts. I go to maybe 200-220 in veg, then up to a max of maybe 300 in flower. This last grow I never got over about 280.

Lately, I have been lowering the lights rather then increasing the watts. It saves on heat in the tent, which makes it easier to cool.

So would you use 300 for my watts/gram or the lowest number or some average? Most people use the rated value I guess, but do they actually use it at that value?

Plus, because Im running LED’s at well below their max rating, and they are running relatively cold, I can get my “300 watt” fixture much closer to the plants than someone running an MH bulb for example. That means I get a lot more photons on the plant for the same number of “watts”.

For my own personal records, I use grams/day. I cant use that to compare to anyone elses grow, but it works for me to track how well Im doing from grow to grow.

We need to just leave light - watts and fixtures - out of it all together :slight_smile:

Sorry man. I am cluttering up your thread. I will gladly remove these posts if you want. I have super thread powers <<<<<<(insert evil laugh here)


Well I do agree that grams/watt is not the best metric in the world, but it is a metric and a commonly used one so it can be a rough benchmark for comparison. And although it’s not totally accurate or informative it still holds some merit…for example you can only grow so much weed under say a 40W fluorescent due to sheer space and photon output limitations

I’ve read your threads before but I guess I wasn’t paying very good attention because if your claimed yields are accurate I’m going to copy LITERALLY EVERYTHING YOU DO haha


meh, to come up with a comparable yield you have to measure photon flux. I was more talking about the psychogenic buds, you know. Like you take a rip off of it and say it was the best in the world. The growing method I use is standardized so i can see if things are going better or worse based on the yield alone. There are other tests I perform to see if the plant I am growing is worthwhile. Point being, the strain you use is integral.

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LOL you guys both just proved my point about how hard it is to get rid of this very bad piece of growing “wizdom”.

Plus, it proves no one reads my toooo long posts! :smiley:

I guess we will have to agree to disagree as they say. Of course, Im still RIGHT and you both are WRONG! LOL!! :wink:


Ha! All you really need to know is how to properly SCROG and LST. Most people use a scrog screen wrong though. They use it to support tall colas, which is fine, but isnt really how it is intended to be used.

To maiximise yields, you need to train the stems UNDER the screen so they are forced to grow sideways instead of up. If you do that, every node that would have produced a single bud will now form a brand new stem. That new stem will now be forming its own new buds.

But wait! Theres more! If you also force those new stems to grow sideways under the screen, they too will throw out even more new stems. Keep that up until the screen is almost full, and then finally let them all go vertical.

I think hydro in general, and especially aeroponics helps with better yields, but its nothing compared to what a well run scrog screen can do for you.

EDIT: @ReikoX also thinks that the large (55gallon) root chambers I have - which allows for huge root balls - also helps increase yields. I think that may be a factor as well.


I’m curious as to what “wizdom” you are talking about? I mean, which specific claim?

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55 gal is that per plant…per strain… not knowing how you do all the magic you do…
do you or how often do you change out that beast? 55 gal of food is a lot of food even if you only put in 42 gals thats still a lot of food.
mesmerize me.

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Sorry if that came across the wrong way. I was trying for a light hearted, 3rd grader level come back. I guess my attempt at humor fell kind of flat.

The ‘wisdom’ I was referring to is the whole idea of using lights as any kind of metric for comparing one grow to another grow. Gram/watt and Gram/fixture both.

I’ll stop clogging up your thread and bow out.

I run air atomized aeroponics. The root chamber is full of air, and roots, and a few million very very very small droplets of water. Its just the single chamber for the entire tent. I have had anywhere from one to three plants growing in it at one time. :slight_smile:

I dont want to mess up Joe’s thread any more. If you want details, click on my name and look for my recent threads. Or do a search for aeroponics and they will show up.


well, if you are comparing grows, you have to obtain the photon flux and the yield per square meter. Those are real numbers. Requires a quantum sensor to determine the moles of photons though. If you have standardized your grow, then you can pick a yield metric and use that to determine if things are going better or worse. So for that kind of comparison grams per watt works fine. So, in summary - if you want to compare grows, use photon flux, but if you are just seeing if you are growing better or worse compared to the last round, any yield metric works as long as you keep using it.


Time can be taken into equation easily. I remember that on old OG, so called “Garden Efficiency Index / GE index” was used to compare gardens. It reflected how much yield was produced by 1 kWh of light energy.

Hypothetical example with 2 pieces of HPS 600 W and 1kg yield.

  1. You need to find out how many kWh your light consumes. Take your watt draw and divide by 1000.
    2 * 600 / 1000 = 1.2 kWh
  1. How much energy did you spend on vegging and flowering?
  • Vegging: 18/6 cycle for three weeks, that is
    18 hours * 21 days = 378 hours

  • Flowering: 12/12 cycle for 60 days
    12 * 60 = 720 hours

  • Total: 378 hours + 720 hours = 1098 hours

  1. Multiply number of hours by kWh your lamp consumes.
    1098 hours * 1.2 kWh = 1317.6 kWh

  2. Take total yield in grams and divide it by kWh: (Hypothetical 1kg yield)
    1000 grams / 1317.6 kWh = 0.76

  • Resulting GE index = 0.76

Grams per Watt can work when comparing standard grows with average veg and flower times. For unusual techniques (really short or really long veg times), GE index (grams per kiloWattHour) is much better.


6lbs from 320 watts? Prove it is all I can say


@Larry3215 has a lot of detailed threads on his grows. He does seem to be able to torture the plants into submission :laughing:.


I was just looking though all the post and saw very few harvest. This is all I could find…he says his best grow was 763 grams which is 1.6 lbs. That’s a far cry from ty he 6 lb mark.


I was more interested in if anyone had considered most properties of cannabis buds to be psychogenic vs something you can measure. hahhah settling on a unit of measure to compare grows, I am definitely going with dr bugbee. the problem is getting people to agree on a metric. doh and be careful about degeneration of the dialog ahem.

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