Watts are really a secondary issue when it comes to LEDs. The first and most important being that LEDs emit light in a very directional manner, so the first question is what are the dimensions of the light.
According to the site it says:
Dimensions - 12.25 x 12.25 x 1.2 in
And that is about all the area it will light, about a foot sqare. Anything outside of that area will not grow. So to do one plant through to about a foot tall you would probably need about 4 of those LED lamps.
The next issue is light penetration. If you bought 4 of them and positioned them on 4 angles around the top of your plant you could quite easily veg them up to a foot without causing stretch. But if you went with the single LED lamp overhead then that light, because it is so directional, will only penetrate the top 2 levels of leaves and you will see slowed growth in the lower branches.
Then there is the issue of flowering. I have tried once to flower with LEDs using 7 LED lights at 16watts per light. The results were crap....
So I veg with my 112 watt LED lamp and then slowly introduce it to the 400 HPS for flowering. I did a CFL flower once too and the results were excellent although I did not save anything in watts, it was basically watt for watt 390 watts of CFLs in all.
socom3riot: as for side lighting, Ive tried that too and side lighting is actually worse than overhead lighting. The LED light is so directional that unless your leaves are droopy, very light of the light touches the leaves and goes right thru to the stem. Then again, I wasnt budding with the LED when I tried that.
In terms of vegging though the LED is fine, as long as you use a ratio of about 1:3 one watt LED where you would use 3 watts of HPS or mH.
Almost all of the online info regarding LEDs has been written by people selling them so the results are usually tainted by that.
Sometimes not overtly tainted though, just not comparable to growing weed.
Example,
LED Testing - HomeGrownLights.com
Their test comparing the 100 watt Procyon to a 400 watt HPS resulted in more weight in lettuce leaves with the LED than with the HPS. I can believe that would be correct....if I or you were growing lettuce, however the height issue is the bit thats missed there.
If they had vegged a plant that grew to say 2 feet under both lamps, the HPS would have won hands down in the end because as mentioned earlier, as the plant extends less light from the LED gets through to the bottom branches than does under the HPS, and I mean, 'a lot less'.
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