I find that my plants(Seedlings) in general are leggy if not enough light - either to far away from light, or not enough. Last week had same prob with outside seeds just planted(not Dan's micro's) and i increased light and put more dirt up higher on stem seedlings and decreased water and added more light -- ok now
$6.87 walmart clamp on silver dome light and $4 Led bulb 75 watt equivalent(only draws 12 watts) and leave on all night then get by sunny window if the #!%$#$ sun will come out
I do use 2 or more at times - I am an no waste energy type and use only what is needed.
Careful not to over fertilize or over water - just adds to leggy, weak stem seedling problems......IMO
Those larger plants are Dan's Micro Multi Floral Trials ( They were planted 1/16/2018 and some have tomatoes, most have blossoms) for next winter - I will put them out as soon as weather is good and the ones that work I will start some more seed in July to grow inside next winter
Pete