Lumens Per Squarefeet

[Mr. Ganja]

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

Mr. Ganja Reviewed by Mr. Ganja on 05-03-2006. Lumens Per Squarefeet What's a good rule of thumb for lumens per square feet? Rating: 5

[Swizzy89304]

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!!!

[LIP]

As many as poss

[Kush Over]

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.

[LIP]

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!

[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

[Kush Over]

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?

[bongerstonerd00d]

[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

[Swizzy89304]

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.

[Zandor]

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.