Good thing you transplanted, was that thing in a paper bowl? Anyways, like shake said, you need to add Perlite to your soil mixture so that over time the waterings don't compress the soil so the water cannot penetrate. You need to water a plant when it needs it, that's the only way to say it, when the soil is dry, let it stay dry for a day or 2, then water it until a small amount comes out the bottom. Then let it dry out completely again. Its called weed for a reason, its doesn't need much water and can live through most anything that NATURE can give it. That should hold ya off for a bit, keep the good questions coming.

Also, for the initial question, yes the plant needs nitrogen during veg, as well as it needs phosphate and potassium at the same time, during flower you just want to cut and eventually eliminate the N to get rid of the harshness.

Sorry for rambling.

-C