How many watts of CFL do you really need?

[sunny747]

I was under the impression that we need at least 3000 lumens per foot up to 10,000 lumens per foot to grow decent mmj. Last week I was commenting on a post and a member was saying that was not accurate and that 1 26w CFL per sqft was just fine.

This doesn't go along with anything else I have read. I didn't want to get into an argument so I let it go, but now it's bugging me

unless you live in the arctic there comes a point where you just can't get enough lumens per sqft with cfl, but I think that 3 26w per sqft is good for veg and 2 26w per foot is ok for veg..

Any thoughts?

 

[AllenHaze]

If someone wants to use 1 cfl per square foot, growth will be slow and likely underdeveloped. There is an exception: If you are growing in a tiny box, with a tiny plant the Inverse Square Law will help a little with the lumen output of a single 1600 lumen bulb. There is still going to be a good deal of disparity in growth response between the lesser and greater amounts of light (more or less bulbs).

I have had great results with cfl, the trick is to use more bulbs in a smaller space and limit the distance between the bulb and plant thereby increasing your lumen availability. A 1600 lumen bulb is putting out 1600 lumens per square feet. At two square feet you are receiving 800 lumens but at half a foot you're at 3200 lumens, at three inches you're now at 6400 lumens (Inverse Square Law). This comes at a cost because coverage is greatly diminished (3 square inches compared to 12 square inches). Keeping the box small helps compensate for lack of coverage (light travels less after reflection). My current veg box is 20 inches deep, 24 inches tall and 24 inches wide with 8x 26 watt cfl. The bulbs are less then 4 inches from canopy. I can veg 5x 1.5 gallon container girls squeezed together in there then transplant them into 3 gallon pots for 2-4 oz yields each.

 

[cassinfo]

If someone wants to use 1 cfl per square foot, growth will be slow and likely underdeveloped. There is an exception: If you are growing in a tiny box, with a tiny plant the Inverse Square Law will help a little with the lumen output of a single 1600 lumen bulb. There is still going to be a good deal of disparity in growth response between the lesser and greater amounts of light (more or less bulbs).

I have had great results with cfl, the trick is to use more bulbs in a smaller space and limit the distance between the bulb and plant thereby increasing your lumen availability. A 1600 lumen bulb is putting out 1600 lumens per square feet. At two square feet you are receiving 800 lumens but at half a foot you're at 3200 lumens, at three inches you're now at 6400 lumens (Inverse Square Law). This comes at a cost because coverage is greatly diminished (3 square inches compared to 12 square inches). Keeping the box small helps compensate for lack of coverage (light travels less after reflection). My current veg box is 20 inches deep, 24 inches tall and 24 inches wide with 8x 26 watt cfl. The bulbs are less then 4 inches from canopy. I can veg 5x 1.5 gallon container girls squeezed together in there then transplant them into 3 gallon pots for 2-4 oz yields each.

ALLENHAZE:::: I can veg 5x 1.5 gallon container girls squeezed together in there then transplant them into 3 gallon pots for 2-4 oz yields each.,.......correct me if I read this wrong, but your saying you can get at least 10 oz with 208 wattage of light? Please share some pictures. I am amazed if that is the case. Thanks

 

[AllenHaze]

That would be crazy talk. I flower under a 450/600W hps in a separate, 4'x3' room.

 

[Milovan]

Use as many CFL's as possible!
That is always your best bet imo.

 

[sunny747]

When I put 8 bulbs in my 2 x 1 x 3 veg box things get a bit warm. I can still pull it off though.

Great info. thank you. I guess the 1 bulb guy stands debunked

 

[TinTizzy]

They say 100 actual watts for first plant and 50 for each additional

 

[AllenHaze]

When I put 8 bulbs in my 2 x 1 x 3 veg box things get a bit warm. I can still pull it off though.

Great info. thank you. I guess the 1 bulb guy stands debunked

Yea. Cfl put out a lot more heat then what is suggested by much of the literature. I have 2x 50cfm bathroom exhaust fan set up as exhaust/intakes. Temps are good so long as outside temps stay below 65ish. I'll tell you, I have had more problems dealing with temps in my veg room - 10x over any I've had with my flower room.

 

[growone]

watts per square foot is a good measure
the minimum i've seen is 50 watts per square foot
100 watts per square foot being more of a max
personally, i do 78w micro cfl grows
with good genetics i see 1 ounce of trimmed bud
which for me is enough

 

[sunny747]

Yea. Cfl put out a lot more heat then what is suggested by much of the literature. I have 2x 50cfm bathroom exhaust fan set up as exhaust/intakes. Temps are good so long as outside temps stay below 65ish. I'll tell you, I have had more problems dealing with temps in my veg room - 10x over any I've had with my flower room.

Yes, people say cfls are cool. I say "really? walk over to that lamp and untwist the bulb with your bare hands then"

 

[sunny747]

watts per square foot is a good measure
the minimum i've seen is 50 watts per square foot
100 watts per square foot being more of a max
personally, i do 78w micro cfl grows
with good genetics i see 1 ounce of trimmed bud
which for me is enough

That's good to know. I have been planning a micro grow box and was wondering if 3 26w would cut it. I am planning 1 ft square, but 6 feet high to dissipate heat.

What size pots do you normally use?

 

[Jussblaz3420]

I got 2-1/2 zips off cfls from 1 auto

 

[TheChemist77]

Sorry to get off topic but im wondering if the minimum is 50 watts per square foot, that would mean a 600 watt hps would cover a 4x3' area is that right?? i thought a 600 watt hps covers a 5x5 area??? basicaly what im trying to ask is if i have a 5x5 grow table how many watts would be recomended to cover it..please dont tell me a 1000watt i prefer useing 400 or 600 watts because you cam put them closer to the canopy, as of now im useing 1 400 watt and 1 600 watt hps above my 5x5 table would you guys say id be better with 2 600s above or can i take the 400 watt out and cover the area with the 600 alone?? better yet what if during veg i ran the 1 ,600 watt mh and when i flip to flower use the 600 and the 400 watt hps bulbs? or as i said should i up it to 2 600 watters??PLEASE HELP AS IM NOT GOOD WITH MATH SO THE LIGHT TO SQUARE FOOT IS MESSING ME UP!! Also if i was useing 2 600s over a 5x5 area how many watts per foot is that?? And what about penetration how deep does a 4oo watt light go and how deep does a 600 watt light go.. i need to know that to know how tall i can let my plants get...

 

[sunny747]

Sorry to get off topic but im wondering if the minimum is 50 watts per square foot, that would mean a 600 watt hps would cover a 4x3' area is that right?? i thought a 600 watt hps covers a 5x5 area??? basicaly what im trying to ask is if i have a 5x5 grow table how many watts would be recomended to cover it..please dont tell me a 1000watt i prefer useing 400 or 600 watts because you cam put them closer to the canopy, as of now im useing 1 400 watt and 1 600 watt hps above my 5x5 table would you guys say id be better with 2 600s above or can i take the 400 watt out and cover the area with the 600 alone?? better yet what if during veg i ran the 1 ,600 watt mh and when i flip to flower use the 600 and the 400 watt hps bulbs? or as i said should i up it to 2 600 watters??PLEASE HELP AS IM NOT GOOD WITH MATH SO THE LIGHT TO SQUARE FOOT IS MESSING ME UP!! Also if i was useing 2 600s over a 5x5 area how many watts per foot is that?? And what about penetration how deep does a 4oo watt light go and how deep does a 600 watt light go.. i need to know that to know how tall i can let my plants get...

This post is about cfl, but to answer your question. Find out how many lumens your lights put out. I see different claims for different lamps and bulbs on the market. Also consider reflectivity, hood quality etc.. I see a 600w hps that claims it produces 95,000 lumens. your space is 25 sqft. 95000 / 25 = 3800 lumens per sqft. From what I have read you can flower with this density of lumens, but it would be better to have more lumens per sqft. 600 w hps works better on a 4x4 grow. Nearly 6k lumens per foot. Way better.

 

[Heavy Consumer]

View attachment 3271551 View attachment 3271551 View attachment 3271553 I got 2-1/2 zips off cfls from 1 auto

That's a lovely bushy looking auto you got there. May I ask, what strain and breeder is it? And also, what light cycle(s) did you grow with and how long did she take to begin flowering? And did you top/FIM/LST her? Thanks for the info!

I'm thinking of grabbing an autoflower strain as a trial run for my new setup (when I eventually get it!), just while the photos that will follow are vegetating and to control my anxiety and keep me occupied with harvesting/trimming/curing while those are in flower. Obviously the light cycle is not as much of an issue with the autos, although I have read some strains are a lot more productive on 18 to 24 hrs of light than they are on a 12/12, hence my questions.

 

[Jussblaz3420]

That's a lovely bushy looking auto you got there. May I ask, what strain and breeder is it? And also, what light cycle(s) did you grow with and how long did she take to begin flowering? And did you top/FIM/LST her? Thanks for the info!

I'm thinking of grabbing an autoflower strain as a trial run for my new setup (when I eventually get it!), just while the photos that will follow are vegetating and to control my anxiety and keep me occupied with harvesting/trimming/curing while those are in flower. Obviously the light cycle is not as much of an issue with the autos, although I have read some strains are a lot more productive on 18 to 24 hrs of light than they are on a 12/12, hence my questions.

Thank! Its a super skunk auto from sensi seeds, took a total of 10 weeks from seed to finish, i ran it under 20/4 and no topping or anythng just a shit ton of LST.

 

[TheChemist77]

This post is about cfl, but to answer your question. Find out how many lumens your lights put out. I see different claims for different lamps and bulbs on the market. Also consider reflectivity, hood quality etc.. I see a 600w hps that claims it produces 95,000 lumens. your space is 25 sqft. 95000 / 25 = 3800 lumens per sqft. From what I have read you can flower with this density of lumens, but it would be better to have more lumens per sqft. 600 w hps works better on a 4x4 grow. Nearly 6k lumens per foot. Way better.

OK Thanks, so its lumens per foot not watts per foot, ill look at my bulbs and figure it out thanks again for the help.

 

[Jussblaz3420]

That's good to know. I have been planning a micro grow box and was wondering if 3 26w would cut it. I am planning 1 ft square, but 6 feet high to dissipate heat.

What size pots do you normally use?

If ur planning on going 6 feet up may i suggest possibly investing in a 150-250w hps for flower, the 150 and 250 watters dont give off too much heat so temps shouldnt be a big issue.

 

[gardengardian7]

If someone wants to use 1 cfl per square foot, growth will be slow and likely underdeveloped. There is an exception: If you are growing in a tiny box, with a tiny plant the Inverse Square Law will help a little with the lumen output of a single 1600 lumen bulb. There is still going to be a good deal of disparity in growth response between the lesser and greater amounts of light (more or less bulbs).

I have had great results with cfl, the trick is to use more bulbs in a smaller space and limit the distance between the bulb and plant thereby increasing your lumen availability. A 1600 lumen bulb is putting out 1600 lumens per square feet. At two square feet you are receiving 800 lumens but at half a foot you're at 3200 lumens, at three inches you're now at 6400 lumens (Inverse Square Law). This comes at a cost because coverage is greatly diminished (3 square inches compared to 12 square inches). Keeping the box small helps compensate for lack of coverage (light travels less after reflection). My current veg box is 20 inches deep, 24 inches tall and 24 inches wide with 8x 26 watt cfl. The bulbs are less then 4 inches from canopy. I can veg 5x 1.5 gallon container girls squeezed together in there then transplant them into 3 gallon pots for 2-4 oz yields each.

They use to copy off of you in school didnt they? Good expression though.

 

[whitebb2727]

I got ten 23w 1600 lumen and 1 65 watt ? lumen in a 30 in x 30 in x 48 in on one plant.

All you can put on them.