I used them to veg/flower just recently (3 month grow, 3 plants), and did nothing to the plants except let them grow naturally in some MG soil and a little flowering nutes... ...got 2 oz's per plant. Just remember to use 3/4th's 6500K (blue) bulbs with 25% 3000K (red) bulbs for veg, and reverse for flowering. I had a 4' x 8 bulb T5...and increased my electric bill by about $30 - $40 per month.
I use it only for veg...I have a 600 w HPS for flower...but the bulbs can easily be changed to accomodate flowering plants.
Here is a post I made about my grow, with pics too. http://forum.grasscity.com/general-...cs-results-t5-veg-flowering-bagseed-soil.html The pics are from a month ago. The tallest plant is still flowering, actually. I took the pictures around day 60, and this sativa wanted to go 90 days. I'm about to chop her down today. Fun fun.