What's the most honest way to express grams per watt?

Is it grams of dried, trimmed bud? Do you ignore trim, leaves, etc.?

What if you added some lights during the grow? Would you figure the wattage just before harvest?

In the case of an LED grow, do you include driver losses and fans? The simplest thing (and the most conservative) would be to insert a Kill-A-Watt into the power line upstream of the closet and take a total reading. LED's, drivers, and fans.

imo, the most honest reading would be G/KWhr used in the complete grow cycle. Of course that would take having a meter (cheap/readily available now) to take actual draw readings of all components used, e.g. lights, fans, heating/cooling, etc. and against dry/cured/usable buds. This would allow for different veg times, flowering times, efficiency of lights/cooling/heating etc. I have metered every device used, if I get some time I'm going to see if I can put a spreadsheet together to capture all components and come up with a G/KWhr number as a baseline against future grows.

Watt would be nice if you could get a peak par value at an agreed distance from manufacturers, divided that number by true draw (killowatt reading), then divided that by what you chopped and dried, a wet read if you will, and then the same formula, but exchange what you chopped and dried, with what you cured for smoking/vaping, or a street read. The PAR reading will act as a common factor describing each lights growing potential and then it's divided by the wattage to see how much that PAR energy costs your system to produce. A lumens per watts for LED growers, if you will. Then the two other numbers are for seeing what you pulled off the plant that can be used and the other a more subjective number but a better demonstration of the street value of your grow. What you can easily make or save. Also I think it separates any blue bias from the PAR reading and too much leafy materiel that some blue based white grows have can have. Unless your Hans and those spiky buds of his. LOL

Too simple, probably, but grams/watt is too simple for LEDs and we could use a formula that everyone can figure out. And you'd have to have some standard for the PAR measurement which isn't easy to get people to agree about I bet. IDK this shit just gets my head hurting.

I agree with you, GroErr, a dedicated meter would be awesome but I doubt people are going to do that. Wait, you could put a Kill-A-Watt in cumulative mode and let it run the whole grow, couldn't you? Wouldn't that give you a number for figuring a G/KWh reading? That doesn't help for comparing to someone's gram/watt number, but from what FJ is saying it almost sounds like too much work to come up with an accurate result for LED. In other words, anyone's gram/watt results on an LED grow is probably at best a guesstimate?

Mellodrama said:

I agree with you, GroErr, a dedicated meter would be awesome but I doubt people are going to do that. Wait, you could put a Kill-A-Watt in cumulative mode and let it run the whole grow, couldn't you? Wouldn't that give you a number for figuring a G/KWh reading? That doesn't help for comparing to someone's gram/watt number, but from what FJ is saying it almost sounds like too much work to come up with an accurate result for LED. In other words, anyone's gram/watt results on an LED grow is probably at best a guesstimate?

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I bought one of those plug-in meters for like $16 on clearance at Canadian Tire, normally around $40 I think. The only limitation with them is if you have something direct-wired but most don't. I had a bathroom fan direct-wired in my original cabinet and ended up just putting a power chord on it to measure it. Most wouldn't go through the trouble, I think that's why GPW is the general yard stick used, a bit of effort required to measure everything. I bought it to monitor, understand, and improve on my usage by device (and thereby cost), it was a real eye opener. That bathroom exhaust fan is being replaced by a spare booster fan, don't need that much exhaust in that cabinet (running LED's in every cabinet/tent/room)) which is now my veg area and the draw on the bathroom fan is twice that of the booster fan. Inline fans are even more efficient when you consider they're much more powerful, I had one in that cabinet too to test it, but it took too much room and anything but the lowest setting on the inline fan would have sucked the walls in - lol I calculated the cost of the bathroom fan 24/7 at about $20/month, vs an inline or booster fan @ about $10/month. Doesn't sound like much, until you have multiple fans/rooms/tents x12 months... Well worth a $15-$30 investment in a meter. The hydro company here has a free one available, all you have to do is call and put up with some marketing/sales pitches.

I only use it as a rough measurement and mainly to tell if there's a difference between runs of the same strain or to compare strains in the same set up. There are just to many variables to make it anything but a rough number when comparing runs. Strain,veg time pot size,growing style,light type and so on.

captain, do you just keep it real simple and divide all your lights consumption against the final dried bud? Do you include fans? Drivers? Come to think of it, it'd be hard to figure out the driver consumption vs. LED consumption, so never mind.

I just use the at the wall numbers for the lights during flower,even the cree bulbs have drivers in them. So just the weight of dried buds and the lights used during flower. Environment is another variable and would depend on where you live,so I wouldn't include fans or air conditioning. If you want to calculate your cost for growing then you would include everything including nutes,growing media and anything else you use. Like I said I just use the rough number to check consistency from grow to grow. If I upgrade the efficiency of my lights I should see a gain in my grams per watt.
The only way to gage your G/W against someone else is if you use the same set up. If the set up is different it's apples and oranges. You could use the general number to maybe see which set up is more efficient but you also have to take into account the growers skill level. Like I said,to many variables.

gpw, as groeer has mentioned, is a crap way to compare grow results.. it does nothing to take into account how much time was spent vegging..

so naturally, a guy who grows trees, vegged for months, is going to get a much better gpw result, than some guy who runs sog, and only veg's for two weeks.. never mind the fact that over a year, the sog setup would more than likely out yield the guy growing trees, gpw doesn't take this into account, and is therefore a pretty horrible meter imvho..

Mellodrama said:

I agree with you, GroErr, a dedicated meter would be awesome but I doubt people are going to do that. Wait, you could put a Kill-A-Watt in cumulative mode and let it run the whole grow, couldn't you? Wouldn't that give you a number for figuring a G/KWh reading? That doesn't help for comparing to someone's gram/watt number, but from what FJ is saying it almost sounds like too much work to come up with an accurate result for LED. In other words, anyone's gram/watt results on an LED grow is probably at best a guesstimate?

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Sorry Mellodrama, missed your question on the first one, you could if you had an electronic version of those that fed back to some storage device, I haven't seen any of the plug-in one's being able to store data for any length of time though. They have limited capacity, doubt anything in the low-end price range could store a whole grow, minimum say 3 months worth of data. The little cheap one I have stores but can only hold about 24 hours and resets. It also has input for your hydro rates so will calculate the actual cost. It's fine though, once you know the draw in KWhr's used by a device you can plug that into a spreadsheet and calculate your cost over time (hours).

racerboy71 said:

gpw, as groeer has mentioned, is a crap way to compare grow results.. it does nothing to take into account how much time was spent vegging..

so naturally, a guy who grows trees, vegged for months, is going to get a much better gpw result, than some guy who runs sog, and only veg's for two weeks.. never mind the fact that over a year, the sog setup would more than likely out yield the guy growing trees, gpw doesn't take this into account, and is therefore a pretty horrible meter imvho..

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Oh contrary my friend. My two week vegged plants out yielded multipasses like 80-90 day veg tree, by about 2.5oz too. Both grown with XGS-190s. Utilization of space is one of the most important things people over look and for a smaller grower with limited space larger plants and long veg time is absolutely not a necessity as a lot believe.

gk skunky said:

Oh contrary my friend. My two week vegged plants out yielded multipasses like 80-90 day veg tree, by about 2.5oz too. Both grown with XGS-190s. Utilization of space is one of the most important things people over look and for a smaller grower with limited space larger plants and long veg time is absolutely not a necessity as a lot believe.

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^^^IN SOIL, your limitations are all based on container size, you veg too long and well, you get what I'm saying............IN HYDRO(generally) racerboy is correct, veg period is related to final yield.

gk skunky said:

Oh contrary my friend. My two week vegged plants out yielded multipasses like 80-90 day veg tree, by about 2.5oz too. Both grown with XGS-190s. Utilization of space is one of the most important things people over look and for a smaller grower with limited space larger plants and long veg time is absolutely not a necessity as a lot believe.

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totally missing my point m8.. all i meant was gpw isn't a very good measure of one's grow.. it doesn't take into account for veg periods.. nothing more, nothing else..

Normally g/W is based on the dissipation wattage of HPS bulbs. So when it comes down to comparing lights, I use LED dissipation wattage to figure grams/W and compare it against my HPS dissipation. (fully dried, trimmed bud)

But once we move beyond simply comparing lights, g/kWh makes plenty of sense taking the whole system into account.

grams per plant per strain. not per watts

This guy knows how to measure his harvest cost and energy used pretty accurately IMO ...

tags420 said:

So the final numbers on the Indagro are in... 284g of grade A nuggets.

Simple Way(Indagro)...
284g/465w=0.61g/w

Real Way(Indagro)...
VEG: 18hr x 26days x .420kW x $.3/kWh = $58.97(196.56 kWh used)
FLOWER: 12hr x 65days x.465kW x $.3/kWh = $108.81(362.7 kWh used)
Total: 559.26 kWh used to produce 284g(.57g/kWh)...or $167.78 to produce the 284g($0.59/g)

If I were not testing the IG's abilities to see what it could do, I would have ran less wattage for veg and saved on the total more(Or if I vegged the hps grow with the hps instead of the AT's you would see higher total numbers). Looking at strictly flower compare to the same strain under hps, the IG did very well and out performed the hps like I thought it was going to. I would imaging just like any lighting system there would be an addition boost from running multiple lights if I had more like I did for the hps.

Simple Way(600HPs)...
990g/1800w=.55g/w

Real Way(HPS)...
VEG: 24hr x 38days x .474kW x $.3/kWh = $129.69(432.29kWh)
FLOWER: 12hr x 62days x 1.8kW x $.3/kWh =$401.76(1449.2kWh)
Total: 1881.5kWh used to produce 990g(.52g/kWh)...or $531.45 to produce the 990g($0.54/g)

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Greengenes707 said:

This guy knows how to measure his harvest cost and energy used pretty accurately IMO ...

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HEY....! wait a second.....That tagz critter seemz familar....? hope he didnt read what i've been saying about him...

I always wonder if people should measure total biomass produced, leaves and stems included since there is a lot of variation on trimming styles and what kinds of buds people include in their final yield. Then you could make a ratio of bud weight to biomass total. But I agree with the people above, grams per kilowatt-hour seems like the simplest and best way to go.

yes gpw should be veg electric as well , but most people figure gpw just from flower , dry bud . not include the fan leafs or trim. or roots soil or water joke .

Haha, obviously not the roots, lmao. But I was just thinking that then you could look at the ratio, I think this would be independent of plant size, and combine that with g/kWh and you'd have a really good idea of the quality of the light and the strain/grower.

Edit: So I thought about it a bit more and maybe instead of the ratio, I would use the fraction of buds: mass of bud/ mass of bud + excess biomass. Then, if you had a perfect plant with no stems and leaves-all buds, the fraction of buds would be 1, and if you had all leaves and stems, the fraction of buds would be zero.