# Rooting Clone Light Requirements



## MeNtAlPaTiEnT (Apr 18, 2008)

Alright, it was either here or the light section...

I recently purchased an 18 watt flouresant tube, warm light. I was expecting it to be a little brighter than it is... It's... well, not too bright. I bought it to give future clones some light to be able to root. About how many lumens would be sufficient for them? I'm GUESSING the light I bought is probably 700-1200 lumens... This light came prebuilt into a ballast and all I had to do was plug it in. No lumen statements on the box whatsoever. I was expecting a much better lumen output until I turned it on. Should I return it or would it provide an adequate light amount for clones? Thanks all!


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## Hick (Apr 18, 2008)

I use tubes for cuttings, but I use the 4' , 40 watters, with a mix of cool and warm bulbs.
 Tubes are pretty inefficient, near both ends. I try not to place anything within a foot of either end. The best lumenocity is found in the center. An 18" tube, probably has less than a foot of good quality light.


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## trillions of atoms (Apr 18, 2008)

Tubes are pretty inefficient, near both ends. 


something that isnt well known rooks' ....listen up!


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## smokybear (Apr 18, 2008)

I would get a couple of the 4' fixtures with a mixture of warm and cool bulbs. That will be perfect for clones to root in. Just my thoughts. Take care and be safe.


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## NorCalHal (Apr 18, 2008)

Hick said:
			
		

> I use tubes for cuttings, but I use the 4' , 40 watters, with a mix of cool and warm bulbs.
> Tubes are pretty inefficient, near both ends. I try not to place anything within a foot of either end. The best lumenocity is found in the center. An 18" tube, probably has less than a foot of good quality light.


 
I use the same.


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## MeNtAlPaTiEnT (Apr 19, 2008)

Hey guys, thanks for the help. I'm going to keep the tube plus I'm going to add a couple 15 watter CFL's installed into a cloning box. This, I hope should be enough as I read they don't really need tons of light.


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## MeNtAlPaTiEnT (May 19, 2008)

Would less light mean slower rooting? Would copious amounts of light mean some rooting and more photosinthesis?


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## md.apothecary (May 19, 2008)

I am using 5 (23w) CFLs both warm and cool whites and have no problems with root growth on an 18/6 schedule. However, after roots start to peek through the netpots (hydroponic) I put them under a HPS light to finish growing.

But... IMO I think that light is very important for root growth, but then again there are other variables as well that can make or break you in veg. Temps, and water/nutrient quality, and pH.


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## swalke1888 (Dec 5, 2008)

Check out my post on lighting calculations...

1200 initial lumens

If your grow room is 3ftX3ft and you keep the light 3 inches away....

The lux at the plant is:
I = P/(A*d^2)

I = 1200/(1m^2)*(.25^2) = 9600 lux

Which should be more than enough for your cloning project.  Of course at the edge of this garden the distance is far more than the 3 inches it is at the center.  So to calculate the maximum distance you should be away from the plant:

d = sqrt(P/(A*I))
For cloning I = 4000 lux

so 
d = sqrt(1200/(0.33m^2*4000lux))= 1ft

Therefore this light can properly illuminate a 1 foot radius circle from a little less than a foot away.


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## Hick (Dec 5, 2008)

swalke1888 said:
			
		

> Check out my post on lighting calculations...
> 
> 1200 initial lumens
> 
> ...


..hmmm..... I see lotsa' impressive calculations, that make absolutely no sense at all...to "me".


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## TheEnhancementSmoker (Dec 5, 2008)

Hick said:
			
		

> ..hmmm..... I see lotsa' impressive calculations, that make absolutely no sense at all...to "me".


 
+1

Does not compute.


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## swalke1888 (Dec 5, 2008)

That true lotsa calculations to get to the same spot...more light = better...luckily for those less inclined to crunch numbers lamps come in various standard wattages (100,175,250,400,600,1000,...) and generally the same kinds of initial lumens these calculations are pretty much standard...but with the advent of new technologies including CFLs I think its important to revisit the whole issue and make sure that its still all worked out


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## TheEnhancementSmoker (Dec 5, 2008)

A lot easier to just figure about 50 watts of HID, or 5000 lumens, per square foot than that Calculus problem you have.


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## I Eat Valium (Dec 5, 2008)

you could get a T-5 4' for about 30 bux. That would be way better.
They are 5000 lumens.


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## swalke1888 (Dec 5, 2008)

TheEnhancementSmoker Im sure that you have your grow all figured up but for the person that asked the question and many more that havent I figured that they may want to know the math behind all of the "rules-of-thumb" that seem to cloud every light question on this forum.  Exact calculations come in handy when trying to save on the light bill and maintance costs as well as when new technologies come along.  I ran the numbers and it seems to have been working but its your call...


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## TheEnhancementSmoker (Dec 5, 2008)

It's just too complicated.  I'm not John Nash or Einstein.


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## swalke1888 (Dec 5, 2008)

Technically speaking, those calculations arent complicated enough; they assume a point source in a far field with no reflection, but lets not get picky.  The amount of light your plants receives is based on the light intensity which has the SI units of lux;  a given light such as a 50W HID provides an intial flux of say 5000 lumens but that is only at a foot away.  This thread is about CFLs which can be kept anywhere from an inch to a foot away from a plant.
Flowering plants need 107500 lux
Veg plants need 27000 lux

Has little to do with lumens...


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