T5 is hot and expensive. Might aswell use 400w HID. I prefer flourecent. Mix of red blue cfl. Highest lumens per watt. 20+ watts per sq ft minimum. shoot for 50. Keep the lights 1-2 inches away.

In my opinion, 6500K T8 4-foot fluorescent bulbs are still the most cost effective. T12 bulbs are obsolescent. I get good results with just the cool white of the 6500K economy grade bulbs. You can get a box of 10 of them for about $25. Paying more for a higher CRI is probably a waste of money for plants. I have tried mixes with redder bulbs in the past, but my plants seem to prefer the 6500K blue white light. Overdriving the T8 bulbs can make them brighter. I do a fair amount of that, but only after I have crowded as many fixtures over my plants as will fit.

Are you unhappy with your fluorescent light results? Like BlackRecluse, I use mostly CFL, but if you have found a system that works for you, why change?

As for growing winter produce, I do it, with careful 'real estate' management...some plants grown in South facing windows, and some under lights. Red Robin tomatoes have been bred to produce in lower light and will fruit if your night temperatures are above 50 degrees. I have also had good luck with Sophie's Choice in a windowsill garden, but since both of these are determinate varieties, you need to have seedlings ready to replace them when they play out.

The miniature bell peppers produced abundantly for me, all winter long, in an unheated sunporch without additional light.

Greens and lettuces however, do well under the lights, if you can keep them from overheating.

Jan

T5's and T8's are the way to go. I agree 6400K-6500K is all you need to use. I prefer T5's as I like getting more light in a small form factor for growing in a small space, but T8's are probably the most cost effective. I've found that these are sufficient in pairs to grow lettuces, but you'll need a bank of them to grow light hungry plants such as peppers or larger tomatoes. In those cases, you'll want to use HID or high power LEDs.

i run t8 - lamps are cheap, and u can overdrive easily, if needed.