Growing/starting with lights information (quick run through)

[Michibacy]

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If you're growing with lights or even starting with lights, it's important to have a light bulb that puts out the correct amount of light and the correct spectrum of light. (and not break the bank)

A lot of people use CFL light bulbs to grow on a budget (the MHD and and HPS bulbs can be very expensive and power consuming).

Utilizing the chart above you can choose which bulbs work the best for yourself. Consider the different light outputs using the Kelvin scale for Color Temp

When choosing between inc., CFL, FL, etc you will notice "watt" as a power rating, this is good as a over all reference, but many professional growers (of all sorts of plants) use the amperage scale to measure electricity usage.

Watts are good to note so you know how much power can be consumed, but the amperage scale is a much more accurate measurement.

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[jekylnz]

This will b a handy post for people to work out wat to use Mich.
Hey also do u know much about L.E.D lights?? I was wondering is it just the color of the bulb,or do they have a uv coating like other bulbs? Cause they work pretty well and r cheap to run,but very expensive here(ova $1000 nzd for good size ones)cause if its just color,..they're real easy to make

 

[Michibacy]

I'm not 100% sure but I believe LEDs use different filliment materials for different color. I know a purple led doesn't necessarily put out UV light though. Uv specific LEDs are needed. A led assembly will have a watt equivalent " rating. If you're good at math you can reverse convert watts to amps knowing your voltage. This helps if you're building a unit or your product doesn't provide the conversion.

Cfl equivalent is roughly 1:4 to inca
led equivalent is roughly 1:10 to inca

 

[Jitterbugdude]

Watts or amperage, it doesn't matter. Since your voltage is constant so will your amps or watts. Use either scale.

 

[jekylnz]

Cheers for that,I wasnt to sure wether u could just get red&blue LEDs and the light color is all that puts out uv &ir

 

[Michibacy]

If it's a red light with clear lens I think it'd work, but putting a film on the plastic lens of a white LED doesn't actually change the color spectrum, if anything it just reduces the output.

Another thing to keep in mind is the lumen output. This is the amount of light you are putting out. A lot of sciency stuff goes into it, but the thing to keep in mind is the efficiency of the unit you are using.

Light type	Typical luminous efficacy (lumens/watt)
Tungsten incandescent light bulb	12.5-17.5 lm/W
Halogen lamp	16-24 lm/W
Fluorescent lamp	45-75 lm/W
LED lamp	30-90 lm/W
Metal halide lamp	75-100 lm/W
High pressure sodium vapor lamp	85-150 lm/W
Low pressure sodium vapor lamp	100-200 lm/W
Mercury vapor lamp	35-65 lm/W

Choose your lm/w rating and use the following formula.

lumens = watts × (lumens per watt)

Higher the lumens, the more light comes out. (essentially)

 

[johnlee1933]

I'm surprised LED's are such low efficiency. Since they are light emitting diodes with electrons directly to photons with no emitter (filament/ gas discharge) I would have thought they would be better. A two watt LED runs a lot cooler than a 2 watt incandescent.

 

[Michibacy]

My charts don't say, but I'm guessing LED's put out a certain part of the light spectrum we can't see, or such high intensity of light that efficiency starts to fluctuate. A good example is coming up on a cop with his lights on, old style halogen bulbs are "easy" on the eyes, you can be pretty close to them without having your retinas effected. If you do the same with an LED, you will surely have temporary blindness do to the intensity.

Maybe it's the lens material?


I could be completely wrong in my assumptions allbeit though.

It appears colors have a huge impact on efficiency
(wikipedia)

Color	Wavelength range	nm Efficiency
	Red	620 < λ < 645	72
	Red-orange	610 < λ < 620	98
	Green	520 < λ < 550	93
	Cyan	490 < λ < 520	75
	Blue	460 < λ < 490	37

(sorry for the rough chart)

 

[Lakota]

This is taken from an led site http://www.stealthgrow.com/facts.htm#intensity and http://www.stealthgrow.com/advantages.htm. I have ordered my led's. I will use them this year on 300 plants and will start another 300 without the lights. I guess in a few weeks I will know if the lights work
[h=5]Forget what you know
about Lumens.[/h] Lumens are a measure of what appears bright to the human eye. Lumens do not reflect what plants see. Yellow light is most visible to the human eye, therefore lights that measure high in yellow light measures high in Lumens. Plants absorb red and blue light during photosynthesis along with trace amounts of other spectrums, including yellow. LED grow lights have lower wattage draw and heat output because they eliminate most of the unnecessary yellow light and give the plants the ideal spectrum for growth and flowering.

 

[grgfinney]

Last year plants took forever to grow till i put a light on them then they went crazy this year i started with leds and they are way ahead of where they were last year

 

[Lakota]

grgfinney how many light do you use and what watt are they?

 

[Michibacy]

This may be considered spam but due to my lack of brain activity at the moment, I burst out laughing saying "what watt" whilst sitting at my desk...

 

[Lakota]

Just think about getting older, most of my days are like that lol

 

[Michibacy]

Another thought on color spectrum. Like I said earlier, 6000-7500K is best for vegetative growth, while the lower is great for fruit.

I wonder if having say 1/3 in the 2500k spectrum would aid in thicker stalk growth and bud growth (keep in mind I'm talking about tobacco)