# Lumens per square foot?



## DUTCH_MASTER (Sep 12, 2009)

*Are lumens per square foot really important during veggin?  I understand it is during flowering, but when veggin only to 12 inches do I really need to live by this?  What's a cheap but effective light for veggin 10 plants?*


----------



## Locked (Sep 12, 2009)

Lumens are always important but you can get by with flouros and CFL's during veg...and then go to HPS for flower....


----------



## DUTCH_MASTER (Sep 12, 2009)

Hamster Lewis said:
			
		

> Lumens are always important but you can get by with flouros and CFL's during veg...and then go to HPS for flower....


Thanx.  Are U using CFL'S?  If so how many will I need for 10 plants?


----------



## Locked (Sep 12, 2009)

DUTCH_MASTER said:
			
		

> Thanx.  Are U using CFL'S?  If so how many will I need for 10 plants?



I only use cfl's for my seedlings now...then they go into the tent under Hid lighting...look up in member list Mentalpatient...he does some great grows with nothing but cfl's....


----------



## DUTCH_MASTER (Sep 12, 2009)

I been getting great feed back.  How can I thank members? My screen does not have the thank you tab any longer.


----------



## Locked (Sep 12, 2009)

DUTCH_MASTER said:
			
		

> I been getting great feed back.  How can I thank members? My screen does not have the thank you tab any longer.



They did away with the thanks button in order to make the site run faster...


----------



## DUTCH_MASTER (Sep 12, 2009)

That sucks.  But thank U Hamster.


----------



## Locked (Sep 12, 2009)

DUTCH_MASTER said:
			
		

> That sucks.  But thank U Hamster.



No problem...that's what we are all here for...keep it green


----------



## The Hemp Goddess (Sep 12, 2009)

You might want to check out the T5 fluors.  They are tube fluoros and are high output.  They have a higher watt/lumen ratio than some of the lower wattage MH lights.  The 54W tubes put out 5000 lumens and are available in 2' or 4' fixtures with 2-8 lights in each fixture.  I used to use a 400W MH to veg, but discovered that my 216W T5 does just as good a job at half the energy usage and heat.


----------



## mountain man (Sep 12, 2009)

Thanks Hemp Goddess ! Good tid bit on Veg lighting !


----------



## DUTCH_MASTER (Sep 12, 2009)

The Hemp Goddess said:
			
		

> You might want to check out the T5 fluors. They are tube fluoros and are high output. They have a higher watt/lumen ratio than some of the lower wattage MH lights. The 54W tubes put out 5000 lumens and are available in 2' or 4' fixtures with 2-8 lights in each fixture. I used to use a 400W MH to veg, but discovered that my 216W T5 does just as good a job at half the energy usage and heat.


Can a 4' four light T-5 fixture provide enough light for 10 or 16 veggin plants?


----------



## ozzydiodude (Sep 12, 2009)

Yes, jusy try to fit all the plants under the lights or rotate them every day to get good light to all the plants.


----------



## DUTCH_MASTER (Sep 12, 2009)

ozzydiodude said:
			
		

> Yes, jusy try to fit all the plants under the lights or rotate them every day to get good light to all the plants.


Ozzy, thanx a million man.  Where did U get Ur avatar?  Its awesome.


----------



## ozzydiodude (Sep 12, 2009)

I been trying to remember myself. it works for me I want to spread Green Mojo around the would. Have someGreen Mojo for your ladies.


----------



## The Hemp Goddess (Sep 12, 2009)

DUTCH_MASTER said:
			
		

> Can a 4' four light T-5 fixture provide enough light for 10 or 16 veggin plants?



LOL--size is relative--how large a plants are you talking about, how large is your space?  I have a 4' 4 tube T5 in a closet that is 4 x 2 x 4.  I get thick lush growth, but think that if the space was any larger, I would add more light.


----------



## DUTCH_MASTER (Sep 12, 2009)

The Hemp Goddess said:
			
		

> LOL--size is relative--how large a plants are you talking about, how large is your space? I have a 4' 4 tube T5 in a closet that is 4 x 2 x 4. I get thick lush growth, but think that if the space was any larger, I would add more light.


  The grow tent is 4x4x6.5.


----------



## Rolling Thunder (Sep 24, 2009)

DUTCH_MASTER said:
			
		

> *Are lumens per square foot really important during veggin? I understand it is during flowering, but when veggin only to 12 inches do I really need to live by this? What's a cheap but effective light for veggin 10 plants?*


 
Yes, I believe you need to live by that rule, if maximum yields are what you're after. I guarantee you that those growers who are averaging 1.5 to 2.0 grams per watt, on a consistent basis, are not vegging under a different kind of light, at lower lumens/sq ft, than they flower under. For maximize yields, you need to get the little ladies into the fastest cycle of growth possible during the veg stage. That usually means giving them the same amount of lumens/sq ft, as soon as they're out of the gate, as they'll receive during the bloom cycle. 

Now, once you have attained a maximum level of momentum in the veg cycle, you want to maintain that momentum going into the bloom cycle. However, that momentum can be easily broken or disrupted by changing changing the light and lumens/sq ft going into bloom. The change of light spectrum and greater lumens/sq ft is enough to stress the ladies and slow their growth; which means a loss of momentum during the transition from veg into bloom. 

However, this advice is relative only to those indoor strains that receive a proper veg period. As you likely know, there are some indoor strains, like Neville's Haze for example, or some tropical pure sativas, that receive no veg period, that is, in terms of the 'veg' light cycle. But for those that do receive a proper veg light cycle, that first 12 inches of growth, and how fast they achieve that height, will have a big impact on their speed of growth during the bloom cycle. - RT


----------



## StoneyBud (Sep 24, 2009)

Hey Dutch Master, there is an easy way to understand this.

It's NOT the size of the room that is a consideration.

It's the size of the PLANT CANOPY.

Plants grow as a result of Photosynthesis. There is a DIRECT relationship to the quantity of lumens striking the plant canopy and the amount of growth and what type of growth a plant will have.

You can use candles from 8 feet above your plants to veg with. You'll end up with skinny, long legged, unhealthy, wispy little half dead plants, but they'll grow some.

However, if you're looking for healthy, thick stemmed, short node, fast growing, thriving plants, you need to approximate what the Sun does in natural light.

The sun, at high noon on the equator, provides about 10,000 lumens per/square foot of surface.

It's not feasible to use 10K lumens in a grow room, because the costs would be astronomical, so 5,000 lumens per/square foot of PLANT CANOPY is an amount that most experienced growers accept as a standard to provide as good of growth as can be, inside.

When the plants are small, they have a much smaller "footprint". That is to say that the PLANT CANOPY is much smaller than it will be when the same plants are flowering.

If you have 12" plants or less, they can be placed closer together where the PLANT CANOPY is a much smaller area to light.

When this is done, it takes less light to make 5,000 lumens per/square foot of PLANT CANOPY than it will later when the plants take up much more area.

So, to make your plants grow at the best overall rate and with the best overall health, you should use 5,000 lumens per/square foot of PLANT CANOPY.

(I've emphasized PLANT CANOPY to make it clear to everyone that the room size IS NOT what you base your light levels on.)


----------



## Rolling Thunder (Sep 24, 2009)

Rolling Thunder said:
			
		

> However, this advice is relative only to those indoor strains that receive a proper veg period. As you likely know, there are some indoor strains, like Neville's Haze for example, or some tropical pure sativas, that receive no veg period, that is, in terms of the 'veg' light cycle. But for those that do receive a proper veg light cycle, that first 12 inches of growth, and how fast they achieve that height, will have a big impact on their speed of growth during the bloom cycle.


 
Oppps! The above statement in not very clear. Not sure what I was thinking about, but the above advice, about vegging under the same light as you flower under applies to all indoor strains, regardless of whether (or not) they`ll receive a proper veg light cycle. 

About the 5000 lumens per sq ft rule, I`m not sure where that came from. I`ve never heard of that before I ventured upon this website. Im one that believes you can do better indoors with far more lumens per square foot, especially if you`re growing a long flowering pure sativa, for example; or sativa dominant hybrids. I would regard 5000 lumens per sq ft as a bare minimum, and not an optimal range for maximum yields. - RT


----------



## StoneyBud (Sep 24, 2009)

Rolling Thunder said:
			
		

> About the 5000 lumens per sq ft rule, I`m not sure where that came from. I`ve never heard of that before I ventured upon this website. Im one that believes you can do better indoors with far more lumens per square foot, especially if you`re growing a long flowering pure sativa, for example; or sativa dominant hybrids. I would regard 5000 lumens per sq ft as a bare minimum, and not an optimal range for maximum yields. - RT


The 5K lumens is the current cost effective amount. More than that, up to the 10K that you get from natural sunlight, is cost prohibitive.

Dealing with electrical costs, heat build-up, air movement and IR from the lamps make 5000 about as much as anyone would want to put on an inside crop.

It's the maximum you'd want, not the minimum.

More than that and you start running into lots of other problems.


----------



## Disco94 (Sep 24, 2009)

Istart of seedling with 4 ft fluros I got at Home Depot for $10 a piece just like the ones you see in cielings but more portable.  Bulbs are cheap.  Once they get bigger I move the fluros to the sides and put CFLs in over them and then HPS for my last 2 weeks.


----------



## StoneyBud (Sep 24, 2009)

Disco94 said:
			
		

> Istart of seedling with 4 ft fluros I got at Home Depot for $10 a piece just like the ones you see in cielings but more portable. Bulbs are cheap. Once they get bigger I move the fluros to the sides and put CFLs in over them and then HPS for my last 2 weeks.


That really doesn't tell us anything about what lumens per/square foot of plant canopy you're using.

Can you tell us that about each stage of your grow?


----------



## Rolling Thunder (Sep 24, 2009)

StoneyBud said:
			
		

> However, if you're looking for healthy, thick stemmed, short node, fast growing, thriving plants, you need to approximate what the Sun does in natural light.
> 
> The sun, at high noon on the equator, provides about 10,000 lumens per/square foot of surface.


 
I totally agree with the above statement; which means 10,000 lumens per sq ft is the natural target range, for growing equatorial sativas (indoors). The further north a plant originates, the less of a difference the extra lumens will make; since we are seeking, after all, to reproduce the plant`s natural habitat indoors.



			
				StoneyBud said:
			
		

> The 5K lumens is the current cost effective amount. More than that, up to the 10K that you get from natural sunlight, is cost prohibitive.
> 
> Dealing with electrical costs, heat build-up, air movement and IR from the lamps make 5000 about as much as anyone would want to put on an inside crop.


 
It would certainly make it cost prohibitve if there was no difference in the crop yield; or if one was not interested in yielding 1.5 to 2.0 lbs per sq metre. That is the question, essentially: Will a maximum of 5000 lumens per sq ft produce the largest possible indoor yield? 




			
				StoneyBud said:
			
		

> It's the maximum you'd want, not the minimum.
> 
> More than that and you start running into lots of other problems.


 
I`m just curious, but is that what the majority of grow guides say? Are these problems insurmountable? CO2 supplementation is just one method of effectively dealing with heat stress, but it seems to be the last choice for many growers. I don`t know why? 

Dealing with all the issues arising from a higher lumens per sq ft ratio takes some work, to be sure, but it can be done, profitably, imo. But then we`re talking about intermediate to advanced growing techniques. - RT


----------



## StoneyBud (Sep 24, 2009)

Rolling Thunder said:
			
		

> I totally agree with the above statement; which means 10,000 lumens per sq ft is the natural target range, for growing equatorial sativas (indoors). The further north a plant originates, the less of a difference the extra lumens will make; since we are seeking, after all, to reproduce the plant`s natural habitat indoors.
> 
> 
> 
> ...


If you used 10K lumens, your yield would increase, but not double from what a 5K lumen grow would produce. It's simply not cost effective to use more than 5K lumens per/sq ft. 

If you want to squeeze out every single gram you can, and don't care how much it costs you, then sure, set up 10K and use it. You'll have to setup WAY more ventilation. It would probably double your crop costs and give you maybe another two ounces per/pound grown under 5K lumens per/sq ft.

With an indoor grow, reproducing a plants natural habitat isn't what the goal is. Maximizing the plants growth is. Those are not the same thing.

The "extra" lumens given a plant strain that originates far north of the equator will make that plant grow far better than it would in it's natural environment. The natural environment *limits* the plants growth, it doesn't maximize it. By adding more lumens than the plants natural environment, the plant will outgrow what it *would* have done in that natural environment.

The difference between the crop yield when grown in 5K lumens per/sq ft and that of an identical grow in twice the lumens wouldn't be worth the difference in dry weight or potency.

If I grow a second crop of weed at 5K per, I'll end up with WAY more weed than you will if you use 10K per on a single crop, and our costs would be very close to being the same. As an example, I would end up with 40 ounces of weed and you would have 25, maybe.

Why would anyone want to do that?


----------



## BBFan (Sep 24, 2009)

I'm not sure I agree with the lumens per square foot based canopy measurement Stoney.

Let's suppose I have a plant that is approximately 24" in diameter under a 400 watt hps with a good reflector in a 10 ft x 10 ft room.  Am I giving that plant 12,500 lumens (based on an average initial output of 50,000 lumens from a 400 watt hps)?  How does disbursement of the light factor in?  Isn't that why we use reflective walls in our grow space, to capture some of that otherwise lost light?  The spread of the light plays a major role in the efficiency of our space, doesn't it?

When lamp output is rated in lumens, that's at about an inch from the bulb.  You get to 12" and you're down to a quarter of those lumens- at 3 feet from the lamp I think it's around 1/9th the lumens.  Now if we can measure lux at the canopy, that would probably be a more accurate measurement.

As far as mimicking / improving on the plants native environment, there is simply no way any light is going to give you the penetration of light that the sun gives.

I grow in a 2.5 ft x 4 ft box under 2- 400 watt units.  I supplement that with some smaller HID units for side lighting.  I started out with 1 - 400 watt unit in that same box, and I can tell you that adding the additional light has more than tripled my yield.  Granted, my canopy has increased, but still, that's a marked improvement.


----------



## StoneyBud (Sep 24, 2009)

BBFan said:
			
		

> When lamp output is rated in lumens, that's at about an inch from the bulb. You get to 12" and you're down to a quarter of those lumens- at 3 feet from the lamp I think it's around 1/9th the lumens. Now if we can measure lux at the canopy, that would probably be a more accurate measurement.


 
Dude, as I told you in my PM, I've just returned from a party. I'm toast.

However, the first thing we have to fix is what you think are the criteria for measuring lumens is.

It's a measurement of the light that strikes the surface of a globe, from exactly 12 inches. Measured in protons.

Please, reform your question into the limitations of those parameters, and tomorrow, when I haven't as much to drink or smoke, we'll progress from there.

I know that you are coming from a stance of what you consider to be the facts of the problem, but you and I need to discuss the problem in detail before drawing conclusions.

Ok, I'm seriously toasted. I'm hitting the sack.


----------



## BBFan (Sep 25, 2009)

Hey Stoney-  Hope you enjoyed the party!

This is from Wikipedia, and basically sums up my understanding of lumens and the rating of the different lights we use in terms of output:



> The lumen (symbol: lm) is the SI unit of luminous flux, a measure of the perceived power of light. Luminous flux differs from radiant flux, the measure of the total power of light emitted, in that luminous flux is adjusted to reflect the varying sensitivity of the human eye to different wavelengths of light. The lumen is defined in relation to the candela by
> 
> 1 lm = 1 cd·sr
> That is, a light source that uniformly radiates one candela in all directions radiates a total of 4&#960; lumens. If the source were partially covered by an ideal absorbing hemisphere, that system would radiate half as much luminous fluxonly 2&#960; lumens. The luminous intensity would still be one candela in those directions that are not obscured.
> ...



I understand that to mean when discussing the lumens produced by a particular bulb, we are discussing the output in terms of energy at the source.

I'm no expert Stoney, so I welcome any insight you can offer.  Thanks.


----------



## StoneyBud (Sep 25, 2009)

Hey BBFan, you've shown an example of the dissipation rate of lumens, but not how the industry standard of the measurement of lumens is accomplished.

One lumen is the light of one candle power on each square foot of a surface of a sphere at a radius of one foot from the light source. 

This is the standard used by all light manufacturers so that the term retains meaning.


----------



## StoneyBud (Sep 25, 2009)

BBFan, are you telling me that if you grew one crop in a 24" x 48" area with one 400 watt HPS, and another identical crop in the same size area with two 400 watt HPS, that the addition of the second bulb would triple the cured weight of your crop when compared to the one bulb crop?

This would have to be done from seedling to harvest on both crops.

Have you done this?


----------



## BBFan (Sep 25, 2009)

Hey Stoney-

I was misinformed on the true definition of lumens, thank you for clearing that up.

So as an aside, would you think that if I am able to keep my plants closer than 12" to the bulb, that I am actually getting more lumens on the canopy?  I knew I should have paid more attention in Physics (oh wait I didn't take physics, I didn't even graduate high school  ).

But dissipation of lumens is critical to what we do.  Under 1 single 400 watt bulb, again using a good reflector, the plant directly under the light at 12" away is receiving significantly more light (presumably the full 50,000 lumens that the bulb is putting out) than a plant to the side, at say 24" from the bulb- at that distance isn't it only 1/4th the amount of lumens?  Is that your position?

To answer your second post- Yes, I grew in a 30" x 48" home built box, from seed, 2 separate grows: the first under 1- 400 watt unit, the second under 2- 400 watt units.  And on a plant by plant comparison, I yeilded 70% more dried and cured bud on the second harvest than the first.  Overall yield was actually 4 times the amount of cured product, but I was able to grow more plants.  There were other factors and differences involved here, but the lighting was by far the single greatest differentiating component.  I am not stating this as any sort of proof, but rather as anecdotal results.

Thanks again for your comments and I look forward to continuing this discussion.


----------



## StoneyBud (Sep 25, 2009)

BBFan said:
			
		

> Hey Stoney-
> 
> I was misinformed on the true definition of lumens, thank you for clearing that up.
> 
> ...


I think you're digging a little deeper than necessary on the lumen count.

The basic rule of thumb used by most of the experienced growers here is that 5K lumens per/sq ft of plant canopy is the most cost efficient amount of light to use. 

I have no idea what the highest amount of light that can be used by MJ is, but I'm sure that if you managed to put that amount of light on your plants without harming them, it would be more cured weight than what 5K lumens per/sq ft produces.

I still say that if you grow one crop under 10K lumens and another under 5K lumens, with an identical set of all other parameters, then the 10K grow would be less than double in cured weight of bud.

Growing more plants in one test than the other isn't a proper test. It has to be the exact same in both grows. What you've said is that by growing more plants, you had more weight....(I should hope so).

Two 5K lumen per/sq ft grows of four plants would out produce the single 10K grow of four plants.

Let me know if you ever try that. Put a watt meter on everything you use to keep that 10K grow going without any heat stress. When you're done, your costs will be much greater than just the difference in light wattage.

We're talking cost effectiveness.


----------



## The Effen Gee (Sep 25, 2009)

DUTCH_MASTER said:
			
		

> *Are lumens per square foot really important during veggin?  I understand it is during flowering, but when veggin only to 12 inches do I really need to live by this?  What's a cheap but effective light for veggin 10 plants?*



Not really but it helps immensely.

I veg under a 600 hps, and would never use anything else.
Flouros just make weak plants and MH seems to be lacking as well.

I can get fully rooted clones in 9 days from cut under a 600. Actually not direclt under, but off to the side.

With proper rotation, I can fully flower 12 plants under 1 600 that is on a 24 hour straight cycle by rotating the plants in and out of light/closet.

I would recommend vegging under a 600 as I have noticed a 400 can cause weak stalks and other problems.

10 plants, depending on the size can be stored under 1 600.


----------



## Rolling Thunder (Sep 25, 2009)

StoneyBud said:
			
		

> It's not feasible to use 10K lumens in a grow room, because the costs would be astronomical, so 5,000 lumens per/square foot of PLANT CANOPY is an amount that most experienced growers accept as a standard to provide as good of growth as can be, inside.


 
I realize you did not say ``all`` experienced growers think that way, which is a good thing, because it shows your willingness to recognize that there are some who disagree with that rule of thumb; but, I`m curious to know what you think of Rosenthal and Soma as growers. Would you regard them as ``experienced`` or maybe even ``advanced`` growers? - RT


----------



## StoneyBud (Sep 25, 2009)

Rolling Thunder said:
			
		

> I realize you did not say ``all`` experienced growers think that way, which is a good thing, because it shows your willingness to recognize that there are some who disagree with that rule of thumb; but, I`m curious to know what you think of Rosenthal and Soma as growers. Would you regard them as ``experienced`` or maybe even ``advanced`` growers? - RT


Why are you asking me of my opinion of Rosenthal and Soma? If they have done something that you wish to make a point of, why not just say it?

Please keep in mind that I've been growing weed since 1949 when Ed Rosenthal was 5 years old.

The 5,000 lumens per/sq ft of plant canopy is something that is used as a benchmark to new growers to let them know what is a good level of light to use, not as an absolute.


----------



## ozzydiodude (Sep 25, 2009)

Quit lying about your age Stoney we all know you were born in the B.C age And gave JC his first bag


----------



## Rolling Thunder (Sep 25, 2009)

StoneyBud said:
			
		

> Please keep in mind that I've been growing weed since 1949 when Ed Rosenthal was 5 years old.


 
I had no idea about the length of your cultivation practice, but it is a good thing to know, as I can now see that there is deep roots to your knowledge. I meant no disrespect. To the contrary, I take my hat off to you. But anyway, to the point: 

Rosenthal has been in the profession for a long time, though clearly not as long as yourself, to be sure. His thick grow guide, co-authored with Mel Frank and published back in the mid-70`s, was my first exposure to serious cultivation practice. I use to make a habit of skipping off classes in high-school just to go and burry my nose in that text. (Not that I recommend that sort of thing today. LOL) My first indoor grow was in 1981, under florescent grow tubes. Pure Columbian sativa. 

Rosenthal`s knowledge and skill, like everyone else`s, has been developing over the years. He doesn`t know everything, to be sure, nor does he pretend to; but in a recent publication of his, he states the following: 

"To produce good buds that are dense and filled with sparkling resin glands, the garden requires a minimum of 35 watts of electrical light input per square foot. The buds grow denser and more potent when the plants are supplied with an electrical input of about 65 watts/sq. ft. At a higher intensity a 1000 watt lamp lights an area of about 16 square feet. A 4' x 8' table is illuminated using two 1000 watt lamps ... etc." ( Marijuana Success Indoors, 2002 copyright, p. 10)

``The garden requires a minimum of 35 watts,`` he says, ``per square foot:`` 35w x 140 lm/w = 4900 lm/sq ft. Now, Soma agrees with Rosenthal, and states the following in his book: ``I have five, 600 watt grow lights above the beds giving me a total of 3000 watts. That`s about 60 watts per square foot, or just over 600 watts per square metre ... etc.`` (_Organic Marijuana Soma Style_, p. 29) Another dude by the name of Mel Thomas, author of _Cannabis Cultivation: A Complete Grower`s Guide_, writes the following: ``Indoor cannabis gardens require 3000 to 9000 lumens per square foot. Successful gardens receive at least 6000 lumens per square foot ... etc.`` (Copyright 2002, p. 14) 

For those who are unfamiliar with Thomas, he was a big-time commercial grower based in London, England. The FEDs code-named him `Mr. Big`, and it took four different police forces working together to bring him down. He was busted for $3.5 million of Skunk weed. The trial judge designated him `a horticultural expert involved in a resolute and successful attempt to produce cannabis on a commercial scale.`(Foreword, p. ix)

There is a good sampling of some experienced growers that take a different view of the question. It would be redundant to quote any others, for the point has already been made, that there are a few well-known and very experienced growers who always grow way above the 5000 lm per sq foot benchmark; which in no way detracts one iota from their skill level as growers. 




			
				StoneyBud said:
			
		

> The 5,000 lumens per/sq ft of plant canopy is something that is used as a benchmark to new growers to let them know what is a good level of light to use, not as an absolute.


 
Well, I can certainly accept that it is a `good` level of light to grow at, especially for a newbie. That is a far cry, though, from saying that one would never, for any reason, want to exceed 5000 lm per sq ft. Respectfully - RT


----------



## Rolling Thunder (Sep 25, 2009)

Rolling Thunder said:
			
		

> For those who are unfamiliar with Thomas, he was a big-time commercial grower based in London, England. The FEDs code-named him `Mr. Big`, and it took four different police forces working together to bring him down. He was busted for $3.5 million of Skunk weed.


 
Just a note of interest, that was $3.5 million worth in the early 1990`s. He and his partner were sentenced to over 14 years in maximum security lock-up; and they were ordered to pay over $210,000.00 in fines, or serve an additional 3 years each, on top of the 14, without parole.


----------



## BBFan (Sep 25, 2009)

StoneyBud said:
			
		

> What you've said is that by growing more plants, you had more weight....(I should hope so).


 
Actually, what I said was this:



			
				BBFan said:
			
		

> And *on a plant by plant comparison*, I yeilded 70% more dried and cured bud on the second harvest than the first.


 
I based it on a plant to plant comparison, not a net weight to net weight comparison. Specifically, my yield was 33 grams per plant at 400 watt relative to 57 grams per plant at 800 watts. And I would venture to say that had I grown the same number of plants, the differences would have been greater due to increased light penetration with fewer plants.

I guess this all started with the lumens per square foot relative to grow space versus canopy. And maybe I'm thinking about it too much. What I am pretty confident about is that 100000 lumens in that space is still not the maximum amount of light I can give them. But I'm working on it.



			
				Rolling Thunder said:
			
		

> "To produce good buds that are dense and filled with sparkling resin glands, the garden requires a minimum of 35 watts of electrical light input per square foot. The buds grow denser and more potent when the plants are supplied with an electrical input of about 65 watts/sq. ft.


 
Don't you think though that this info, even though it's less than 10 years old, is dated, particularly in consideration of LED's?

Forgetting heat issues for a moment, do you think running 400 watts of cfl's in a 10 foot space would be the equivalent of 400 watts of HID?  Is there a difference in the quality of light?  Or is a watt equal to a watt, regardless of the source?


----------



## StoneyBud (Sep 25, 2009)

Rolling Thunder said:
			
		

> Well, I can certainly accept that it is a `good` level of light to grow at, especially for a newbie. That is a far cry, though, from saying that one would never, for any reason, want to exceed 5000 lm per sq ft. Respectfully - RT


Who said that? I surely never did. I said, many times, that 5000 lumens per/sq ft was the most cost efficient amount, and with your examples, you also said it. 

May we quit beating this dead horse?


----------



## Rolling Thunder (Sep 25, 2009)

BBFan said:
			
		

> Don't you think though that this info, even though it's less than 10 years old, is dated, particularly in consideration of LED's?


 
Yes, it is very dated! His magazine coloumn(s) will contain his very 'up-to-date' knowledge and practice. I know for a fact Rosenthal is currently working on a test project with an LED company. Just as he was one of the earliest to go totally HPS, and promote solo HPS growing, I suspect he'll become one of the very first 'big' promoters of LED as well. I myself have full intentions of going all LED before long, and then eventually plasma; if I can convince myself that the plasma light source is superior to LED. 



			
				BBFan said:
			
		

> Forgetting heat issues for a moment, do you think running 400 watts of cfl's in a 10 foot space would be the equivalent of 400 watts of HID? Is there a difference in the quality of light? Or is a watt equal to a watt, regardless of the source?


 
To be honest, I have'nt given cfl's much thought. My attention has been more focused on MH and HPS, until recently. Now it is more focused on LED and Plasma lighting, though I still have my doubts about the grow capacity of Plasma lighting. From what I can see, or my limited perspective, the immediate future belongs to LED lighting. If you have money to invest, invest it in some LED light stock(s). Plasma lighting will still take a while to get it together.

Based on the little I know about cfl's, I'd chose 400 watts of HID over 400 watts of cfl, any day of the week; but as I say, I'm not that knowledgable of the state of the art cfl, and its true growing capacity. - RT


----------



## Rolling Thunder (Sep 25, 2009)

StoneyBud said:
			
		

> May we quit beating this dead horse?


Most certainly. As I said, no disrespect was intended. :48:


----------



## stonedrone (Sep 25, 2009)

I'm going to go ahead and jump in here. 

I have seen several very successful grows on this site using well below 5k lumens per sq. ft. Many of the grows that I have witnessed just shot for over 3k psf. That square footage was based on the size of the grow room in each of these grows. 

Stoney this is the first time I have seen somebody say that the room size is not what is important but rather the size of the canopy. While that does make some sense to me as you need sufficient lumens to penetrate said canopy, you will actually increase the amount of lumens that hit the plant with a good reflective surface close to that plant. There is such a thing as lumens dissapation that is why all manufacturers test under the same circumstances. I do agree however that you can have a successful grow with one 400w light over the top of 2 to 4 plants in any sized room however you will increase the amount of lumens that hit said plants in a smaller room with reflective walls, hence increasing growth rate and overall yield.

One more thing that I am sure of is that every time you double the distance from a light source you decrease the amount of light hitting a certain point by 75%. For example if you have 50k lumens at 1 ft you have 12.5k lumens at 2 feet.


----------



## StoneyBud (Sep 25, 2009)

stonedrone said:
			
		

> Stoney this is the first time I have seen somebody say that the room size is not what is important but rather the size of the canopy. While that does make some sense to me as you need sufficient lumens to penetrate said canopy, you will actually increase the amount of lumens that hit the plant with a good reflective surface close to that plant.


The reason I said that is for this example:

Mr. Smith has 4 seedlings that are each 2 inches tall. He places the seedlings in his grow room which is 12 feet by 12 feet in area.

His seedlings are in the center of the room.

Now:

1. If room size were the way to determine your light amount, then Mr. Smith would need lights creating 720 thousand lumens to cover his entire 12 foot by 12 foot room at 5,000 lumens per/sq ft.

2. If plant canopy is used to determine how much light is used, then Mr. Smith would find he needs 5,000 lumens over his seedlings.

Please, the 5 thousand lumens is just an example. Don't freak out on me about the 5 thousand lumens per/sq ft.

My question is this; Why would Mr. Smith use his room size as the determining factor for his lights on the 1 square foot of plants in the middle of his room? What if his room was 200 feet by 200 feet and he only used the center 1 square foot of area?

So, with that in mind, THAT is why I said to use the plant canopy size to determine the number of lumens needed. The plants are what is being lighted, not the entire room.

NOW PLEASE FINISH READING THIS:

Later, when Mr. Smith uses topping and LST to FILL the entire 12 foot by 12 foot room, his canopy would then BE THE ROOM SIZE and he would use the room size as his determining factor for light needed.

Do you understand what I'm getting at here?


----------



## stonedrone (Sep 25, 2009)

I'm not trying to disagree with you Stoney, on the contrary as a matter of fact. I am sure to read every single post of yours that I see on this site. I just feel that it is more beneficial for Mr. Smith to put those 4 seedlings into a smaller area as the light that would normally escape would be reflected back onto the plants. My statement about the 5k lumens was not directed towards you, I was just pointing out that 5k is plenty for a good grow. Most of the experienced growers on this site say 3k is what we need and 5k is what we should be trying for. 

Although I may ne be all that eleoquent in my statements I am not trying to say that any one person is wrong. I like to take part in these debates because I tend to retain more information this way. It seems to me that an edjucated debate is more likely to produce facts and proof than just a collection of statements which are usually based in opinion.


----------



## StoneyBud (Sep 25, 2009)

stonedrone said:
			
		

> I'm not trying to disagree with you Stoney, on the contrary as a matter of fact. I am sure to read every single post of yours that I see on this site. I just feel that it is more beneficial for Mr. Smith to put those 4 seedlings into a smaller area as the light that would normally escape would be reflected back onto the plants...


I agree also. Lots of people here start their grows with huge lights over tiny seedlings. I was attempting to show that if someone had a smaller light to start off with, they could save some money AND have great results by lighting only the plant canopy initially. That would take much less light.

Some growers also have very limited funds and use only small CFL's to light their grows. By lighting only the canopy, they can also save money by using only the amount of lights needed at each stage of the grow.


----------



## stonedrone (Sep 25, 2009)

I like the way you explain things Stoney. Thanks.
:48:


----------



## Rolling Thunder (Sep 25, 2009)

stonedrone said:
			
		

> It seems to me that an edjucated debate is more likely to produce facts and proof than just a collection of statements which are usually based in opinion.


 
Hey there stoned, 

How's it goin' dude? You would'nt be implying anything, would you? Let the record note that educated people read and take into consideration the opinions of others better educated and trained than themselves. I deferred to Rosenthal, Soma, and Thomas because I regard them as superior growers, to myself. Try and get through College or University without ever "quoting" other sources of information. The quotes I posted are firmly grounded on years of empirical observation and first hand knowledge of the subject at hand. Peace bro'! - RT


----------



## stonedrone (Sep 25, 2009)

That's exactly what I'm talking about Rolling Thunder. Although not in the context you seem to have taken it. What I mean is that when you are debating with somebody you are almost required to show some sort of proof or a quote from a professional rather than just answering a question with your thoughts. I'm a straight forward person and I don't tend to imply anything I may disagree with. 

You quoting Rosenthal, Soma, and Thomas is part of what makes this an edjucated debate rather than just a collection of opinions. Cheers.


----------



## Rolling Thunder (Sep 25, 2009)

stonedrone said:
			
		

> You quoting Rosenthal, Soma, and Thomas is part of what makes this an edjucated debate rather than just a collection of opinions. Cheers.


 
Well, just leave it to me to get my wires crossed again. Thanks for clearing things up for this stoned homer. Btw, great signature you got there. I just noticed it! Socrates was the man, indeed! :48:


----------



## stonedrone (Sep 25, 2009)

:bong: :48: :argue: :bong: :48:


----------



## Pepper (Sep 25, 2009)

DUTCH_MASTER said:
			
		

> *Are lumens per square foot really important during veggin? I understand it is during flowering, but when veggin only to 12 inches do I really need to live by this? What's a cheap but effective light for veggin 10 plants?*


 

To answer your question in a very simple way  

The very simple answer to your question is *YES the more light the better*, and if someone tells you otherwise they are full of it, plain and simple, and if you are looking for yield leave the word cheap at home because it does not belong in the garden  A plant 12" tall tells me nothing. How wide is the plant? You can have a plant 12" tall that is 8" wide and you can have a plant that is 12" tall that is 20" wide so has you can see that makes a HUGE difference in the amount of light you will need. If I were you I would use a minimum of a 400w hps for vegge 600w hps would be even better, and a 1000w hps even better in my experiance hps works much better for vegge than MH that is why I do not vegge with MH bulbs.

Many growers make the mistake of "ignoring" the vegge period but little do they know the vegge period is THE most important phase of a plants life IT will make or break your final yield.

First question you need to ask YOURSELF is. *What is the main reason I have a garden, and how much yield do I want? *THE answer to that question will dictate how much light you will be using in your garden plain and simple.

Always mesure light usage by plant canopy, and not by the size of the floor space, also VERY important idially the plant canopy should be no more than 1' away from the walls of your room, the reason for that is better light penetration throu the plant canopy.


----------



## uptosumpn (Oct 1, 2009)

Ok, so I think I got it......If using a 400HPS, (limited funds right now) which produces around 55,000 lumens, I can get the "benchmark maximum" of 5000 or more amount of lumens per SF "plant canopy" If I put 12 plants in 7" wide 3gal bags with 3" spacing between them in a 3.5'w x 3.5'd "plant canopy area??


----------



## BBFan (Oct 1, 2009)

uptosumpn said:
			
		

> Ok, so I think I got it......If using a 400HPS, (limited funds right now) which produces around 55,000 lumens, I can get the "benchmark maximum" of 5000 or more amount of lumens per SF "plant canopy" If I put 12 plants in 7" wide 3gal bags with 3" spacing between them in a 3.5'w x 3.5'd "plant canopy area??


 
If you're planning on growing in a 3.5' x 3.5' under 400 watts, you'd be better off only doing 4 plants in 5 gal pots.  My space is very similar to that (2.5' x 4') and I use 2- 400 watters.  The most I fit under there is 8 plants, and I didn't maximize yield.  I'm trying the less is more approach.

Good luck to you!


----------



## uptosumpn (Oct 1, 2009)

Ok, I just realized I had the plant count wrong...after talking with a friend who used 3 400watt hps, (130,000 lumens) in a 24sf area.(3'd x 8'w) He put 8 plants in 2gal bags under each light and got an average of 2oz dry per plant ...(autos) which is what i'll be growing:hubba: So yes, less is more, but not 4?! BTW, I already have 3gal bags..so gotta use what i have. Thanks




			
				BBFan said:
			
		

> If you're planning on growing in a 3.5' x 3.5' under 400 watts, you'd be better off only doing 4 plants in 5 gal pots. My space is very similar to that (2.5' x 4') and I use 2- 400 watters. The most I fit under there is 8 plants, and I didn't maximize yield. I'm trying the less is more approach.
> 
> Good luck to you!


----------



## The Hemp Goddess (Oct 2, 2009)

uptosumpn said:
			
		

> Ok, I just realized I had the plant count wrong...after talking with a friend who used 3 400watt hps, (130,000 lumens) in a 24sf area.(3'd x 8'w) He put 8 plants in 2gal bags under each light and got an average of 2oz dry per plant ...(autos) which is what i'll be growing:hubba: So yes, less is more, but not 4?! BTW, I already have 3gal bags..so gotta use what i have. Thanks



  I'm sorry, but I have a very (very, very, very, very...) hard time believing that your buddy was getting this kind of dry yield--over 1 gram per watt with autos in 2 gal bags that were only given 1 sq ft each????????

Do not expect anything close to this, especially when you are starting out.  If you get 1/4 oz per watt with autos when starting out, this is good.


----------



## uptosumpn (Oct 2, 2009)

My mistake! Hemp Goddess,  I was quoting his yeild amount from his other grow using 2 x 1000hps in a 25sf area...! with 23plants @ 2+ oz each....

But, with the 3 x 400hps he got 1oz dry per plant! with 7 plants underneaath each 400hps...I was high.. {1oz per. is the amount i'm going for:hubba: }




			
				The Hemp Goddess said:
			
		

> I'm sorry, but I have a very (very, very, very, very...) hard time believing that your buddy was getting this kind of dry yield--over 1 gram per watt with autos in 2 gal bags that were only given 1 sq ft each????????
> 
> Do not expect anything close to this, especially when you are starting out. If you get 1/4 oz per watt with autos when starting out, this is good.


----------



## BBFan (Oct 2, 2009)

uptosumpn said:
			
		

> My mistake! Hemp Goddess, I was quoting his yeild amount from his other grow using 2 x 1000hps in a 25sf area...! with 23plants @ 2+ oz each....
> 
> But, with the 3 x 400hps he got 1oz dry per plant! with 7 plants underneaath each 400hps...I was high.. {1oz per. is the amount i'm going for:hubba: }


 
He must be an amazing grower.  You should listen to everything he tells you and not bother with the people here.  That's still over 2 grams per watt  - tell him to sign up here- I could use some advice from him!


----------



## MrNorCal (Oct 2, 2009)

BBFan said:
			
		

> He must be an amazing grower.  You should listen to everything he tells you and not bother with the people here.  That's still over 2 grams per watt  - tell him to sign up here- I could use some advice from him!



Hey BBFan I think your math is a little off. Either that or mine is(which is entirely possible) But when I plug in the number I am getting 0.644 grams per watt with the 1000's and 0.49 grams per watt with the 400's for this guy's grow.


----------



## BBFan (Oct 2, 2009)

MrNorCal said:
			
		

> Hey BBFan I think your math is a little off. Either that or mine is(which is entirely possible) But when I plug in the number I am getting 0.644 grams per watt with the 1000's and 0.49 grams per watt with the 400's for this guy's grow.


 
Hi MrNorCal- How's the grow room going?

You're absolutely right!  It's my math that was off!

Please accept my apologies uptosumpn.


----------



## uptosumpn (Oct 2, 2009)

No problem man...that's what this site is for right? to have constuctive criticism.....

anyway, he is a member here...and here is his journal from start to finish.....! big room sf with small plant canopy sf...just like what Stony Bud has been saying.....
http://www.marijuanapassion.com/forum/showthread.php?t=20531


----------



## MrNorCal (Oct 2, 2009)

The grow room is going good. The girls are just about 3 weeks now from seed. They are really starting to take off. Soon, I hope within 2 weeks, I will start taking clones.


----------

