And can i use a 100w reptile bulb

No for the first question.
Probably no for the second question.

Watts aren't really relevant in growing things. You need to find out how many lumens the bulb is putting out, and at what spectrum.

I use bulbs that are only 45W - but put out 2800 lumens at 5500K. They work great, but cover a small area (fit into a regular socket). If you are growing more than a few small plants at once it would be easier to use a long fluorescent type.

added: Also, my 2800 lumens is on the low end for a grow light. I've had some issues because of it, with certain plants getting leggy or pale in color because they want something stronger.

It works for me---but will depend on what you are trying to grow and how quickly you can adjust things if needed.

This post was edited by SaraElise on Fri, Apr 26, 13 at 19:47