Watts per sq ft. How many watts in your grow space

[Garage_Grower]

Rocking 13.5w/sq ft in my 4’x6’ cabinet, 5x 3500k Autocobs. Pulled 756g from my last 4 plant run, which is 2.33gpw.

 

[BigSm0]

My big space is 9 x 9 81 sq ft with 13 autocobs from @BigSm0 totaling 780 watts so I'm running 9.6 watts per sq ft

12 auto cobs in a 4x8. 8x 3500k 4x 6500 k. Thinking about putting 4 more in there. 2 on each side. View attachment 1152922

As we spoke the other day dabber the numbers don’t lie. 9.6 watts per square foot and the only grow I’m seeing come close is @Blu_tri at 22 watts per square foot. Nothing gets my blood pumping like someone telling me I need to do something differently when I continuously dominat that persons wildest expectation. Math and numbers are fun but real world results are the true test.

Like many here I listened to the consensus on wattage needed for ideal growth. After a few grows years ago with my newly purchased cob lights I found it wasn’t working. When I thought about the hours of light autos receive vs photos it all made sense. I multiplied the wattage by the hours of use. My autos were getting hammered. Say you are running 500 watts on photos at 12 hours per day and running the same 500 watts on autos at 24 hours per day the autos are getting twice the light per day. It’s clear as day. So the first thing I did was messaged the owner of the light company and asked him to consider a smaller light a little more suited towards Auto growers. My 468 watts packed into a 20” square grow light was way to powerful. He laughed at my idea so that’s when I made my own. Since I have proven this isn’t just a theory and the consensus was wrong. You WILL do better with 15-20 cob watts over 50 on autos and for photos you will do better with 20-30 cob watts rather than 50.

https://www.autoflower.org/threads/bigsm0-and-the-cob-addiction.61479/

I think my average was around 11-15 watts per square foot in most grows.

 

[BigSm0]

In my closet which is 2x2x48 1 spider farmer SF-1000 pulling 93 watts, 1 65 watt hlg qn pulling 65 watts and 1 2700k auto cob pulling 54 watts but that's for flower only. If someone can help a brother out with the math it'll be much appreciated!!

just some quick math I’d say you are running a lot more wattage than I’d suggest.

 

[Death The Cultivator]

As we spoke the other day dabber the numbers don’t lie. 9.6 watts per square foot and the only grow I’m seeing come close is @Blu_tri at 22 watts per square foot. Nothing gets my blood pumping like someone telling me I need to do something differently when I continuously dominat that persons wildest expectation. Math and numbers are fun but real world results are the true test.

Like many here I listened to the consensus on wattage needed for ideal growth. After a few grows years ago with my newly purchased cob lights I found it wasn’t working. When I thought about the hours of light autos receive vs photos it all made sense. I multiplied the wattage by the hours of use. My autos were getting hammered. Say you are running 500 watts on photos at 12 hours per day and running the same 500 watts on autos at 24 hours per day the autos are getting twice the light per day. It’s clear as day. So the first thing I did was messaged the owner of the light company and asked him to consider a smaller light a little more suited towards Auto growers. My 468 watts packed into a 20” square grow light was way to powerful. He laughed at my idea so that’s when I made my own. Since I have proven this isn’t just a theory and the consensus was wrong. You WILL do better with 15-20 cob watts over 50 on autos and for photos you will do better with 20-30 cob watts rather than 50.

https://www.autoflower.org/threads/bigsm0-and-the-cob-addiction.61479/

I think my average was around 11-15 watts per square foot in most grows.

Is the amount of umols put out in relation to wattage and efficiency part of the soup?

Do autos need half DLI spread out over 150-200% the time a photo needs?

Would changes in spectrum allow stronger light? Can a plant manage being blasted by 3500k for 24 hours for 8 weeks or does it need a range of spectrum?

 

[Olderfart]

Is the amount of umols put out in relation to wattage and efficiency part of the soup?

Do autos need half DLI spread out over 150-200% the time a photo needs?

Would changes in spectrum allow stronger light? Can a plant manage being blasted by 3500k for 24 hours for 8 weeks or does it need a range of spectrum?

Do we know the optimum DLI for cannabis? How much does it vary by strain? Is it a constant total no matter the daily light regime, or does it vary? Lots and lots of questions. None easily tested specifically for autos due to genetic variation between seeds...

In the meantime, pragmatic experience suggests to me that trying less light may work reasonably well with autos. That will certainly be one focus of my next auto grow.

Happy light adjustment all.

 

[LazyNhazy]

Is 320w in 2x4? My other room is a 5x5 with ts2000 2 Mars cobs 100w each for flower. With 2 6500k cobs for veg and later flower.

 

[Boognelson87]

Is the wattage to sq feet even worth calculating? I can see it being a guideline. A year ago I had 270 true watts of blurples not good results and now I'm running 235ish of qb and its night and day difference. In my same set up I'd be fine with 165 watts of cobs in my setup. And that's 20 watts sq foot basically.

 

[Death The Cultivator]

Do we know the optimum DLI for cannabis? How much does it vary by strain? Is it a constant total no matter the daily light regime, or does it vary? Lots and lots of questions. None easily tested specifically for autos due to genetic variation between seeds...

In the meantime, pragmatic experience suggests to me that trying less light may work reasonably well with autos. That will certainly be one focus of my next auto grow.

Happy light adjustment all.

SGS has an opinion on it but to some degree it doesn't really matter because the ones asking those questions are probably different from your average auto grower.

Is the light bright? Is the brand known? Can I grow pounds? Is it energy efficient?

Vs.

Are the diodes top bin? Umols per watt/$? What is the PPFD at 8, 12, 18, 24, etc? Are they trying to steal my money with buzzwords like UV, IR, Emerson effect? Beam angle?

 

[Death The Cultivator]

Is the wattage to sq feet even worth calculating? I can see it being a guideline. A year ago I had 270 true watts of blurples not good results and now I'm running 235ish of qb and its night and day difference. In my same set up I'd be fine with 165 watts of cobs in my setup. And that's 20 watts sq foot basically.

I don't think it's worth calculating when GPW is inaccurate itself.

Horticulture light group offers several ppfd charts for their lights at different heights with output and efficiency report.

HLG 550 V2 Rspec

High Efficiency Commercial Indoor Horticulture LED grow light designed to replace a single-ended 1000watt HID with just 490 Watts. 1257 PPF @ 2.6PPF/W. Full-spectrum. Reliable passive-cooled design. Powered by Samsung LM301H LED and Deep Red LED 660nm

horticulturelightinggroup.com

Their output report and ppfd reports are what I look for. Ppf, ppfd, umols are what I look for.

 

[Disburped]

Is the wattage to sq feet even worth calculating? I can see it being a guideline. A year ago I had 270 true watts of blurples not good results and now I'm running 235ish of qb and its night and day difference. In my same set up I'd be fine with 165 watts of cobs in my setup. And that's 20 watts sq foot basically.

Most of the stoner-way to measure things are kind of useless.

As we spoke the other day dabber the numbers don’t lie. 9.6 watts per square foot and the only grow I’m seeing come close is @Blu_tri at 22 watts per square foot. Nothing gets my blood pumping like someone telling me I need to do something differently when I continuously dominat that persons wildest expectation. Math and numbers are fun but real world results are the true test.

Like many here I listened to the consensus on wattage needed for ideal growth. After a few grows years ago with my newly purchased cob lights I found it wasn’t working. When I thought about the hours of light autos receive vs photos it all made sense. I multiplied the wattage by the hours of use. My autos were getting hammered. Say you are running 500 watts on photos at 12 hours per day and running the same 500 watts on autos at 24 hours per day the autos are getting twice the light per day. It’s clear as day. So the first thing I did was messaged the owner of the light company and asked him to consider a smaller light a little more suited towards Auto growers. My 468 watts packed into a 20” square grow light was way to powerful. He laughed at my idea so that’s when I made my own. Since I have proven this isn’t just a theory and the consensus was wrong. You WILL do better with 15-20 cob watts over 50 on autos and for photos you will do better with 20-30 cob watts rather than 50.

https://www.autoflower.org/threads/bigsm0-and-the-cob-addiction.61479/

I think my average was around 11-15 watts per square foot in most grows.

It makes sense, in the north where the light shine 24/0 the light is less intense than at the equator where it shine 12/12. It also shine less intense during night but it's never dark.

Is the amount of umols put out in relation to wattage and efficiency part of the soup?

Do autos need half DLI spread out over 150-200% the time a photo needs?

Would changes in spectrum allow stronger light? Can a plant manage being blasted by 3500k for 24 hours for 8 weeks or does it need a range of spectrum?

It's different for different species but weed don't need darkness. My opinion is that dark period for autos is nonsense but if I for some reason would want to let the plant rest I would try to dim it a few hours to simulate night in the far north.