Originally Posted by psteve
So only 90 actual watts.
That is almost enough light enough for a 1 foot by 1.5 foot canopy (canopy is the lateral space occupied by the top of the plant, that is exposed to the most direct light), of a plant less than 24 inches tall.
If you want a bigger plant to produce satisfactory buds, you will definitely need a lot more light.
If you are going to use exclusively fluorescent light, you should be trying for more than 70 ACTUAL watts per square foot of canopy, and still try to keep your plant height as low as possible by using a scrog, LST, or some other supercropping technique.