the 25 watt screw in one needs to be daylight, and a compact flouresent. normal white light bulbs that you would find in you avarage light socket are around 3500k which doesnt do much. it must be daylight. i read that heat lamps are actually bad for plants, it raises the temp and plants dont like that!
this is what you want!
you NEED DAY LIGHT!
"soft white" or "bright white" will not work
they should say something like 100 watt equivalent but is only 23 watts. and for the sake of growing plants, 23 watts means 23 watts, so ignore wat it is equivalent to.