your problem is your dirt, walmart topsoil is shit, look at all that leftover bark mulch mixed in with it... those plants look like they are suffering from a BAD pH problem and possibly nute burn as well.... you need to start seeds in seedling starting soil , NOT jiffy pellets, their pH is TERRIBLE, and then transplant into better dirt, even miracle grow is better than that shit.. I think the floodlight is not your major issue, as long as it's in the blue range and doesn't run too hot it should be fine.
That one plant that looks like it has good structure, bushy and short internodes even though it's burnt, says to me that your light is adequate.