A couple years ago, I made a large shelf to start my seedlings on. After learning a thing or two about starting seeds this year, I modified the shelf to what you see below. The entire unit is 4′ wide, 2′ deep, and about 6′ tall. There are three shelves, and the top two have florescent lights (three double fixtures per shelf). The light height is adjustable, and I keep them low enough to touch the tops of the plants. One end of the light may be lower than the other depending on the height of the plants on either end of the shelf.
The bottom shelf is being used for storage for now because I don’t have enough outlet space for another three lights. I’ll figure that out next year. I have all of my lights plugged into a surge protector (power strip), which is plugged into a lamp timer that turns the lights on at 6am and off at 10pm.
Each shelf is large enough to fit 4 regular size flats. With the newspaper pots I made, I can fit 36 seedling pots in each flat. Go HERE to see instructions on making the seedling pots. Once my tomato plants got huge, I moved them outside to a small greenhouse. Unfortunately, we had a hard frost a few days later and all of them froze. They still have strong stems and roots, and I can see some of them putting out new leaves.