Originally Posted by eyewtkas

A good way to find out if you have enough CFL lumens is to calculate your lumens per square feet.

First, get the square feet of your growspace by multiplying length x width.

In my case, I have a 1.875 Sq. ft growing space.

Next, get your total number of lumens.

In my case, I'm using x4 42w CFL's that give out 2600 lumens each, so a total of 10,400 lumens.

Next, divide the total lumens by your square feet growspace and you will end up with lumens per square foot.

2600 lumens x 4 = 10,400 lumens / 1.875 sq. feet = 5546.66 Lumens Per Square foot

And according to a post I saw (I will look for the link, but it might be from another grow site) you need:


a MINIMUM of 2,000 lumens per square foot. But expect crappy buds with the minimum.

5,000-7,000 lumens per square feet and you get decent sized buds

7,500+ lumens per square feet and you start getting nice fat buds.

of course, the more lumens you have in your growspace, the bigger the buds will be.

so use this as a little basis. it has always worked for me.