Answer: Your plants need good strong direct light. The plants' leaves need to be quite close to the bulb, within just a few inches. (Raise the light as the plants grow taller.) The longer fluorescent bulb will probably work better if you have more than one plant. If you have a lot of plants, 24 inches with a single bulb is probably not going to light up a large enough area.
For seedlings like this that are only grown indoors temporarily, ordinary fluorescent bulbs are fine; in a shoplight hood (holding two bulbs) you might use one warm bulb and one cool bulb if you want to extend the spectrum a little bit but ordinary bulbs are fine. To give you an idea of how much space, you can fit two flats lengthwise under a single four foot shoplight hood. The number of plants per flat depends on what size container you use for each plant.
I hope this helps.
Q&A Library Searching Tips