Grams per watt vs grams per square meter

Basic Growing Info
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Here is the conundrum. Some growers have the luxury of not having to use passageways and for the same reason can report a certain gram per square meter.

Lets say I have a 1m square space and I get 100grams per m2. People assume that if you increase from 1m square to 100m2 that the yield increase would be proportional. 1m=100g so 100m=10,000grams. But I believe it is not so. Labor becomes a issue after a certain point and as I asked above, what about the passageways?

If I have a 100 m square grow room with 10 meters of passageways, how do I configure my grams per square meter???

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I think you should subtract the passageways.

First - it makes you look better when you report stats :slight_smile:

Second - it just makes more sense.

If you have a 1000 sq meter room, but are only using 1/2 of it to grow in, it makes no sense to report based on the full room area. Or look at it the other way. If you have 20 plants that take up 10 sq meters. with say 10 light fixtures, your numbers will look stupid if you have them in a 1000 sq meter room and they will look great if you have the same exact setup in a 10 sq meter room.

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I like one statement in particular, every grower should have a plaque on the wall stating that simple fact, ā€œI donā€™t believe it matters which metric you use as long as you improve with every harvestā€¦ā€ Itā€™s a continuous learning curve, every strain and every change :slight_smile:

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well I see 2 grams per watt average on a regular bases in a 4x4 areaā€¦ thatā€™s with a 660 watt lightā€¦ the math would be 1320 grams of medicineā€¦ divided by 16 sqft of spaceā€¦ 1320/16 = 82.5 grams of product per square footā€¦ 1 sqft equals 0.092903 of a meter and 16 sqft equals 1.48645 square metersā€¦ so that would be 1320 grams in a 1.48645 meters of spaceā€¦ the math on that would be 1320/1.48645ā€¦ so 888 grams per square meter is what Iā€™ve seen done regularly now with LEDsā€¦

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Maybe pull 2g/watt in hydro and using top of the line led like spydrx etc??

I donno, personally, everytime I see someone posts about pulling 1.5-2g/watt they cant back it up with proof. That or the grow took a year from start to finish.
As mentioned above, efficiency isnt measured in g/W. time and materials need to be taken into account.i

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It doesnā€™t really mater what metric you track, so long as it is the same metric. Then you will see if improvements are made or not. No denying if you are running a large operation, it is a business. Complicated cost analysis can and should be done, considering investments, electricity, lease, nutrients, overhead, labor, RO I, etcā€¦

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the time from rooted clone til harvest on my calculations is about 12 weeksā€¦ 3 weeks of vegā€¦ 9 weeks of flower.

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I wish I could get 888g per square meter.

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I go by how often i need to buy cannabis. One time and my efficiency needs to improve. Ha! Ha! (sorry just amusing myself)

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thatā€™s pushing it without co2ā€¦ but it is being doneā€¦ and @Kraven hits that all the time with his setup

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My current gpw average is 2.107 on each 4ā€™ x 4ā€™ grow space. My best has been 2.215 gpw on a mono crop of Instant Cookies, and a ho hum average run is 1.9 ish to 2.0 gpw.

Edit: I run a 1k eqivilant commercial LED [510w draw] and push CO2 @ 1300ppm over each 4x4 footprint.

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so if I understand correctly 4x4=16ft2. 16ft2 = 1.48m2. I assume that the multiplier would be 510w x 2.1g to give us a total of 1071grams per 1.48m2 for a total of 724 grams per meter. Great job. Thanks. :+1:

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10 days to root a clone, 14 - 18 days tops in veg and 9 weeks in flowerā€¦every 90 days nearly on the dot I finishā€¦never sooner and sometimes a week later. Peep my thread and see a proper grow that is getting those numbers consistanly year in and year out.

The Bunker

my work 2.jpg576Ɨ1024 144 KB

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My grow tent is 7.3 sq ft or .68 sq meters. I have been averaging 275 watts on my LED light.

This is my first grow, but I have hi hopes, so IF I get 1 gm/watt = 275 gm. that would work out to 275/.67 = 383 gm / sq meter.

Thats with 4 plants, so I would be getting almost 69 gm / plant - over about 14 weeks.

Im new at this, but none of those metrics by themselves seems to really express it very well.

I think maybe which one or ones you use will depend on the size of your grow. Small, individual growers like me dont really care about gm/watt or gm/sq ft so much as total yield over time.

I have a fixed space that cant get any larger and I cant afford to add more lights. My main thing is getting enough from one or two grows over the fall/winter/spring to last me through the hot summer days. I have no AC, so summer temps are a major concern.

Cost is also a big factor for me, but I have not run the numbers on that yet. Ive been afraid to find out how much I have actually spent so far! Its way to easy to drop $10 or $20 on some small thing and think nothing of it, but those small things add up over time. Thats on top of the initial expense of building the tent, LED lights, PH meter, fans, nutes, etc etc.

I need to go over my electric bill in detail and see what its costing me. I think its around $30-$40 / month extra, but Im not sure. My bills always go up in the winter anyway. That plus nutes and seeds will be my main expenses once Im done building stuff :slight_smile:

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Not sure how to open with my reply. So choose 1 or 2 please.

  1. Ainā€™t that the truth
    2.You are telling Noa about the flood.

One of my partners says he worries more about going with me to home depot than he worries about how much a dancer will cost all night at the strip club.

Congrats con your g.p.w for a first grow. Took me probably a year to even make it to harvest.

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The placement of the lights is whatā€™s critical, plant arrangement is simply about space and movementā€¦ I prefer rectangular spaces as it gives me the best layout for staggering plants on opposite sides of the room so i can trellis plants towards each other. Every branch becomes a cola :slight_smile: The more light coverage, the better.

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We all started somewhere, the only ones who had initial success had experienced folks help them or they followed guides. Iā€™ve never grown in spaces smaller than 400 square feet. Itā€™s a learning curve for life BUT an enjoyable one. Lotā€™s of how toā€™s about :slight_smile:

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The elephant in the room is STRAINā€¦ grams per watt is very strain dependentā€¦ you canā€™t get out of itā€¦ what ainā€™t in itā€¦

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i want to do a clone run some timeā€¦ i usually veg for 1-2 months. i worry about flipping too early and sacrificing yield but i think iā€™d be better off running an efficient perpetual. i think i hit close to 1g/w in my 4x4 w/ 735w and a 2 month veg but only 1 of the 5 plants was a decent producer and i think 735w is too much light for my space. will be flowering this round ~600w

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I was just about to start a very similar thread although I was going to start one about grams per CUBIC foot per week.

This would let us consider vertical growing as well and give us a standard way to measure the efficiency of a vertical system compared to a top down system.

At the end of the day there seem to be two broad camps.

There are people who are going for ultimate quality, or a particular high. This can be for many reasons. Maybe they can grow as many plants as they like, use as much electric as they like, and have as much space as they like. At this point, quality is king and overrules all other considerations. For these people efficiency can be ignored.

Then there are people who are limited in what they can do by factors out of their control, some people need a quiet system. Some people are limited by space, others by power.

For these people, who are not able to produce as much as they would like, efficiency is king and they need to maximise that to get the yield they need.

As they smoke the same every day (I assume) their needs are measured in grams per week. If their space is limited then they will need a certain amount of grams per CUBIC foot per week, unless their restriction is power, then grams per watt rules but this is covered in many other threads. Using volume instead of area lets us consider all systems, not just the top down. It may be that for certain spaces top down is not the most efficient system, and this can be established.

Myself, on my last run, I got 1.05 grams per watt from HPS, but I got 50g per square foot as I grow vertically. If we include the height then per CUBIC foot I got 6.25 grams per cubic foot over 10 weeks (including veg time) which works out to be 0.625 grams per cubic foot per week. This is just the grow space and does not include ventilation etc but does include the nutrient tank and root space.

THAT is a number that tells you the efficiency of your system. I am very interested to see anyone elseā€™s numbersā€¦

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