You should have a look at the

http://boards.cannabis.com/indoor-li...uch-light.html

thread, which is stickied and answers many/most of these questions.

Lumens are a measure of the power of light as perceived by the human eye. (And before anyone starts to talk about plants "seeing" differently...the human eye is able to perceive light in the wavelengths used to grow.) You can grow a plant with 3000 lumens per square foot, but you're definitely on the low end with that. 5000 lumens per square foot and up is what you want to strive for.

As noted, CFLs don't have much canopy penetration. Distance form the plant is much more important for CFLs. Light from any source decreases in intensity in exponential relation to distance; the amount is the square of the distance form the source. Double any distance from a source and the amount of light will be one quarter of the previous amount. If you've got an HPS light, the 1 1/2" difference between 7" and 8 1/2" won't be huge. With a CFL, the difference of 1 1/2"...going from 1 1/1" from the plant to 3" from the plant...is the difference between getting some buds and getting nothing.

For vegging, you want to find what will be called "daylight" or "full spectrum" bulbs. They should be 5500k to 6500k.

For flowering, you will want to use "warm white" bulbs. These are more common. They are usually 2700k.

Ignore the "watt equivalent." Watts have nothing to do with growing. Watts are a measurement of energy, not light. Lumens aren't perfect, but they're more than accurate enough to determine if you have enough light.
Roughrider Reviewed by Roughrider on . CFL'S Whats best for veg/flower? Watts, Lumens? Ok i have read a lot of grows here with cfl's and no one really has a standered of light as to how much to veg/flower for optimum growth. With all the cfl growers now, wouldn't it be nice to find some sort of standard guideline. As of now, its just the more the better it seems, or someone that thinks they can use 1 cfl from start to finsh. Im not saying some people have it dialed in, i could put out some names, but we all know who you are:thumbsup: I wondered if we could do some side by Rating: 5