If the plants are grown in a hydro set up or soil has yrs are the same rule's apply the grow medium wants to be moist not sodden dripping wet.Allow the seedling to dry out a little this will promote good roots but not so dry that it becomes crumbley,get the light has close to the top of the seedling has possible without causeing it to burn or it will just become too leggy.Same has if you are growing in a hydroponic sytem you must allow the plants if in rock wool to get a good root structure through the small cube then put in the next size up wait untill this cube has good roots comeing through the bottom before even thinking about turning the hydroponic stem on unless you are useing a aeroponic system with no media then the mist sould come on reg basis.But i would say that the seedlings at the size yrs are at will need prob one water a week perhaps a little top up round about day 5 but when you water let the excess water run off you def don't want a young seedling sat in stagnent water.........tyke.........