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Thread: Lumens Per Squarefeet

  1. #1
    Mr. Ganja is offline Registered
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    Lumens Per Squarefeet

    What's a good rule of thumb for lumens per square feet?

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  3. #2
    Swizzy89304's Avatar
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    You want at LEAST 5,000 lumens per square foot for a decent plant, although with mylar, you may get away with 3,000 - but dont expect brilliant yields, plus the buds will be fluffy and not that potent. Also it will take longer to veg and flower, and youll want to harvest the top of the plant first, then the bottom, unless you use some CFL's to light the bottom buds.

    7,000 will give you some damn potent bud, but youll still want to harvest the top first then the bottom, unless you dont mind having some fluffy bud thats not as potent as the main colas. It will also be quite dense.

    10,000 lumens is what you want ideally, IF you can control the heat, humidity etc. With 10,000 lumens per square foot, you can harvest the whole plant at once, with no noticeable difference in the potency of bottom buds - although they will be a little bit fluffier unless you get some extra lighting in for the bottom. Youre looking at rock hard buds, and it will be as potent as the packet describes. Also, you may be able to harvest a little bit earlier than normal, but only by a week at most.
    Dont bother with anything more than 15,000 lumens per square foot, as the extra light is unusable by the plant. It can only absorb a certain amount, plus youll have to take care of the extra heat and electricity costs. For closet/stealth growers, either a 250w or a 400w MH/HPS will do the trick. Anything more than that and youll be wasting your money.
    REMEMBER, THERE ARE OTHER FACTORS THAT DETERMINE POTENTCY AND YIELD - NUTES USED, SOIL, HYDROPONICS, PH OF THE WATER, HUMIDITY, TEMPERATURES, DRYING, CURING... THESE ARE ONLY SOME OF THE FACTORS!!!
    Last edited by Swizzy89304; May-03-2006 at 13:58.
    Quote Originally Posted by SensiRide
    Swizzy I'm going to have to be honest with you here. When I saw you photo the 1st thing I thought is that you look really old, like in your thirties or something then I had a second look and realised you were probably a bit younger, like 28 or 29, so I'm shocked to find out you're only 18.
    ^^^ I reckon thats pretty cool actually.
    Photos of Herb I upload are MY property. Its our right to smoke Herb freely, as it was put on this planet by Jah and is my free will to do what I and I want.

  4. #3
    LIP's Avatar
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    As many as poss

  5. #4
    Kush Over's Avatar
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    Quote Originally Posted by LIP
    As many as poss
    LoL. You just made me have an idea..

    "As many as possible. All right!"

    I could imagine someone trying to place a kilowatt of HPS on a square foot of space almost right up to the bulb; then try to put a fan between it and the light to solve the 'heat' problem only to come to realize it's actually the intensity of light turning the once green plant into a tanned pile.

    As many as possible is right, but there is a limit. Although I doubt this scenario is remotely possible [ no one's that stupid ], it's still in the realm of possibility.

    LIP and Swizzy are both right. Simulating the same environment the plant receives outside, light wise, is a good start with any grow.

    The Earth-Sun distance tells us, on a cloudless day, that there will be roughly ten thousand lumens per square foot at ground level. Let's try to get as close to that number as possible, but don't exceed it by much -- that is, don't put more than maybe 12k lumens per square foot or there's a chance you're going to bleach the plant, and 12k may still very well be too high.

    I've got a 150 watt HPS that can and will bleach parts of the plant that are immediately under the 16,000 lumen bulb [ well, 13,500 mean lumens ]. The damage isn't a result of the heat so much as it's a result of just being, well, bleached.
    "I didn't inhale." - Bill Clinton
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  6. #5
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    Well, your very right. Dont want too mant intensities. I supose if you had a 1k HPS you'd just have to have it about 5 metres above the plant lol!

  7. #6
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    Just wonderin

    I have done a great deal of reading, and I have yet to see where it was suggested that you have 10,000 lumens per sq. ft. That would mean to have optimal growing conditions you would need 1000 watt HPS in a grow cabinet that measures 4 x 3.5 feet, roughly. Damn, how the hell would you keep that cool? If 10K per sq. ft. is the number, then all the hydroponic sites are dead wrong on their suggested coverage area per light, and advertising falsely. I wish some of the other experienced growers would shed some further "ight" on this (no pun intended).

    I am just a noob idiot, but I love to read.

    peace all,
    b0nger

  8. #7
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    Quote Originally Posted by bongerstonerd00d
    I have done a great deal of reading, and I have yet to see where it was suggested that you have 10,000 lumens per sq. ft. That would mean to have optimal growing conditions you would need 1000 watt HPS in a grow cabinet that measures 4 x 3.5 feet, roughly. Damn, how the hell would you keep that cool? If 10K per sq. ft. is the number, then all the hydroponic sites are dead wrong on their suggested coverage area per light, and advertising falsely. I wish some of the other experienced growers would shed some further "ight" on this (no pun intended).

    I am just a noob idiot, but I love to read.

    peace all,
    b0nger
    Well, if you're looking to produce optimum growing conditions, you'll follow Mother Nature's example with the Earth-Sun distance. I myself use several thousand lumens per square foot, and I can still see room for improvement.

    Cannabis requires a lot of light -- as much as we can provide. This means that we'd need to replicate the environmental conditions seen outdoors -- 10,000 footcandles/lumens per square foot on a sunny day. Three thousand, like what is suggested on some cannabis cultivation sites, is minimal and typically produces lower yielding plants of sometimes questionable quality [ i.e.: less dense buds ].

    And a 4' x 4' SCRoG/SoG space under a 1000w HPS/MH isn't unheard of, even in cabinet grows. The key is ventilation, which includes good intake and definitely good exhaust, especially around the light.

    Air-cooled hoods, anyone?
    "I didn't inhale." - Bill Clinton
    [ A Presidential candidate at the time ]

    "Make the most of the Indian hemp seed, and sow it everywhere!" - General George Washington
    [ A note to his gardener at Mount Vernon, on the year 1794 ]

    "First they ignore you; then they mock you; then they punish you; then you win." - Mahatma Ghandi
    [ Indian independence leader ]

  9. #8
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    [QUOTE=Kush Over]Well, if you're looking to produce optimum growing conditions, you'll follow Mother Nature's example with the Earth-Sun distance. I myself use several thousand lumens per square foot, and I can still see room for improvement.

    Cannabis requires a lot of light -- as much as we can provide. This means that we'd need to replicate the environmental conditions seen outdoors -- 10,000 footcandles/lumens per square foot on a sunny day. Three thousand, like what is suggested on some cannabis cultivation sites, is minimal and typically produces lower yielding plants of sometimes questionable quality [ i.e.: less dense buds ].

    And a 4' x 4' SCRoG/SoG space under a 1000w HPS/MH isn't unheard of, even in cabinet grows. The key is ventilation, which includes good intake and definitely good exhaust, especially around the light.

    Air-cooled hoods, anyone?[/QUOTE]



    No need to be a smartass! Sorry I asked the fuckin question. I figured that is how folks learned to grow on this forum. Maybe I should have started by posting "What do I need to know" and skipped the 3 weeks of reading I have done. In the future, I will make sure I ask as few questions as possible. Please, accept my apology.

    And, by the way, I am familiar with air cooled hoods, but I was NOT aware with ventilation and fresh air you could keep temps low enough to use that many lumens per sq. ft. A legit question I thought, but what the fuck do I know?


    b0nger

  10. #9
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    Quote Originally Posted by bongerstonerd00d
    No need to be a smartass! Sorry I asked the fuckin question. I figured that is how folks learned to grow on this forum. Maybe I should have started by posting "What do I need to know" and skipped the 3 weeks of reading I have done. In the future, I will make sure I ask as few questions as possible. Please, accept my apology.

    And, by the way, I am familiar with air cooled hoods, but I was NOT aware with ventilation and fresh air you could keep temps low enough to use that many lumens per sq. ft. A legit question I thought, but what the fuck do I know?


    b0nger
    Erm... hes being a smartass by teaching you something new (telling you that you need fresh air coming in and the hot, old air going out) in order to maintain decent temps?
    To me it looks like hes teaching you something... to which you start whining and being bitchy at him. Jeez, smoke a spliff, chill out.
    Quote Originally Posted by SensiRide
    Swizzy I'm going to have to be honest with you here. When I saw you photo the 1st thing I thought is that you look really old, like in your thirties or something then I had a second look and realised you were probably a bit younger, like 28 or 29, so I'm shocked to find out you're only 18.
    ^^^ I reckon thats pretty cool actually.
    Photos of Herb I upload are MY property. Its our right to smoke Herb freely, as it was put on this planet by Jah and is my free will to do what I and I want.

  11. #10
    Zandor's Avatar
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    The goal is to give the plant 10,000 lumens of the proper color light for the plants life cycle.
    That said there is nothing wrong with more lumens either.

    You can argue how you get it 10,000 lumens but that does not change the minimum goal.
    Peace
    Zandor

    If you go cheap you grow cheap. - Me

  12. #11
    Mr. Ganja is offline Registered
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    I will aim for around 4,000-5,000 in my planned flower room. Thanks.

  13. #12
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    Will be excellent for a first grow. Ive got 7,000 lumens per square foot from a 250w HPS, and I would still use the 600w HPS but the heat that it generates just isnt funny. In the winter it would be fine, but my room would be bloody freezing because Id have to leave the window open. Get a few sheets of mylar aswell if you can, its dirt cheap if you shop around and worth every penny/cent.
    Quote Originally Posted by SensiRide
    Swizzy I'm going to have to be honest with you here. When I saw you photo the 1st thing I thought is that you look really old, like in your thirties or something then I had a second look and realised you were probably a bit younger, like 28 or 29, so I'm shocked to find out you're only 18.
    ^^^ I reckon thats pretty cool actually.
    Photos of Herb I upload are MY property. Its our right to smoke Herb freely, as it was put on this planet by Jah and is my free will to do what I and I want.

  14. #13
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    Quote Originally Posted by Swizzy89304
    Will be excellent for a first grow. Ive got 7,000 lumens per square foot from a 250w HPS, and I would still use the 600w HPS but the heat that it generates just isnt funny. In the winter it would be fine, but my room would be bloody freezing because Id have to leave the window open. Get a few sheets of mylar aswell if you can, its dirt cheap if you shop around and worth every penny/cent.
    Well, I wont be growing right now, but I'll be getting a house in about a year. Right now I'm just doing my homework and making blueprints. And I've got some money saved up solely for growing. I'm gonna devote a basement room to growing. A 10 x 10 x 8 should be good. I'll make partitions with wood, so I'll have a flower room, which I'm aiming to be around 25 square feet. The Veg room will be slightly smaller.

  15. #14
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    Sounds nice, Ganja

    My flower closet/room will be 8'x4'x8', and my veg is going to be 4'x4'x8' high. I plan on having a clone cabinet also. Will you be using hydro or soil? I am hoping I can fit a 24 pot (http://www.hydroponics.net/items/details/multiflow.asp) << this one in my flower room/closet. If I cant get all 24 in, I am figuring I can run at least 18. Pots are only 9 inches in diameter, so it'll be close. I guess I'll go with Super Sun 2 1000 watt HPS (2 of them in flower cabinet). That will give me around 8100 lumens per sq.ft. I figure with 18 pots I can get at least a pound per harvest. Space is not an issue with me, I live alone in a 14 room house, but I am going to use a spare bedroom I can close and LOCK the door on.




    good luck when you get started,
    b0nger

  16. #15
    latewood's Avatar
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    Quote Originally Posted by Mr. Ganja
    What's a good rule of thumb for lumens per square feet?
    your question is vague... Even though you have been answered...Did you get the answer you were looking for?
    What are you asking? do you want to know the minimum lumens per sf necessary to grow under?
    Or, Do you want to know how many lumens to equal the sun's Output?
    what rule of thumb are you asking about?

    Glad to help, but didn't know what to tell you. lw

  17. #16
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    My grow room is no where near my bedroom, but the lighting in there is SO hot it basically warms my whole house.. I havnt used the heating in ages.

  18. #17
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    LW

    Got my answer bro. I figure if I use the 2 1000 watt lights I will have enuf lumens per sq. ft. (32 sq. ft.)

    Lip, I am going to be venting my heat outside bud, I have existing duct work that comes from basement I use to vent furnace with. I can easily tie into that with little problem. Will actually make furnace vent better because it will cause a draw since I am blowing the exhaust into it. Will check for outside noise, and if needed, I can add mufflers on the fans. But I am figuring (and this fucks me most of the time) but due to the length of the run, and I am going to use insulated duct, I should not have a noise problem.


    b0nger

  19. #18
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    Quote Originally Posted by bongerstonerd00d
    I have done a great deal of reading, and I have yet to see where it was suggested that you have 10,000 lumens per sq. ft. That would mean to have optimal growing conditions you would need 1000 watt HPS in a grow cabinet that measures 4 x 3.5 feet, roughly. Damn, how the hell would you keep that cool? If 10K per sq. ft. is the number, then all the hydroponic sites are dead wrong on their suggested coverage area per light, and advertising falsely. I wish some of the other experienced growers would shed some further "ight" on this (no pun intended).

    I am just a noob idiot, but I love to read.

    peace all,
    b0nger
    the hydro lighting co's are telling you the maximum coverage area for a particular light with a reflector
    250w...2x3
    400w...4x4
    600w...6x6
    1000w...8x8, they are not telling you that you are equaling the footcandles per sf. that the SUN puts out.

    gotta go...will check back later. lw

  20. #19
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    lol

    i don;t know how anyone would grow with out venting it dude =) the cooler it is the more nutrishion your babys eat the hotter the more water they go throu Lip my be heating his house but his babys i bet could use more Co2 than Stale air

  21. #20
    latewood's Avatar
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    Hellllll yeah...2-1000's...I like Zandor's answer...

    If you want a real good lighting read. Aside from the good
    info here @CDOT...then go to Weedfarmerdot.

    I have 2 1000's in my flower room now 1mh agrosun gold
    1hps eye horilux. that is as close to the sun as you'll get I suppose. goodluck lw

  22. #21
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    Quote Originally Posted by latewood
    your question is vague... Even though you have been answered...Did you get the answer you were looking for?
    What are you asking? do you want to know the minimum lumens per sf necessary to grow under?
    Or, Do you want to know how many lumens to equal the sun's Output?
    what rule of thumb are you asking about?

    Glad to help, but didn't know what to tell you. lw
    Well, I meant how many lumens per square feet would be needed to produce some good bud that I'd be able to smoke and do other things with.
    I think I'll be well short of matching the sun's output, I'll aim for half of that amount and try to develop the top colas.

  23. #22
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    Quote Originally Posted by bongerstonerd00d
    My flower closet/room will be 8'x4'x8', and my veg is going to be 4'x4'x8' high. I plan on having a clone cabinet also. Will you be using hydro or soil? I am hoping I can fit a 24 pot (http://www.hydroponics.net/items/details/multiflow.asp) << this one in my flower room/closet. If I cant get all 24 in, I am figuring I can run at least 18. Pots are only 9 inches in diameter, so it'll be close. I guess I'll go with Super Sun 2 1000 watt HPS (2 of them in flower cabinet). That will give me around 8100 lumens per sq.ft. I figure with 18 pots I can get at least a pound per harvest. Space is not an issue with me, I live alone in a 14 room house, but I am going to use a spare bedroom I can close and LOCK the door on.




    good luck when you get started,
    b0nger
    Thanks.
    I'm gonna go hydro. I like the DWC system, everyone here seems to get good results with it.
    Space wont be an issue with me either, I'll have the basement to myself. Which could be mean 2 to 3 rooms and a large closet.
    A pound per harvest would be ideal, that's 5 grand in the bag right there.

  24. #23
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    Interesting read, this thread....

    I wanted to comment something:
    In my grow cabinet, I have one 400W MH, and one 600W HPS.
    So... let's say we've got 35,000 lumens in the MH... and, say, 90,000 lumens in the HPS... (figures are "conservative", I would think).

    The eternal question::: Can these lumens be added?
    If not, I would be having with the HPS
    90,000 lumens / 5.55sq.ft. = 16,216 lumens/sq.ft.

    With the MH only
    35,000 lumens / 5.55sq.ft. = 6,306 lumens/sq.ft.

    (cabinet dimensions: 20"x40" = 800sq.in./144 = 5.55 sq.ft. )

    Ideas?

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