Plant Stunted and yellowing

Hey all ... my plants have been growing well and are about 3 weeks or so in however one of my plants has slowed right down in the growing process and is turning yellow. My other two are growing really strong. I'm only growing in soil, no ferts or nutrients added, just water. Got a 400 watt lamp also. Basically the leaves has stopped growing but the stem appears to have grown upwards though. The leaves are turning yellowy and slightly drooping. Could this be a drainage problem ? If so wat should i do as dont really want to transport the plant in case of damage ... looks like it might be quite delicate.

Cheers for any help.

Bob

Young plants can be healty and seem to droop. Yellowing may be from lack of oxygen to the roots do to not letting the bottom of the pot dry out. What size pot are you using and how much do you water? Most of the time it would be overwatering but it is hard to tell with a young plant with out seeing it.