This is just to show you how easy it is to bury those long stretchy stems ,
After you replant them make sure you lower your lights so they wont continue to stretch
I do not have a pic of one of those seedlings with the long ass stem reaching for a light that's 2ft high
But i got this one that i internally let slightly stretch a little , you can see the slight stretch at the bottom of the stem
You do not want your soil wet when you do this
its best for the soil to be dry so the extra soil will come off the roots easier
After you take your plant out , GENTLY break lose the soil from around the roots
After you got the excess soil off the roots , put some soil back in the bottom of your cup or pot
you dont want to put your plant right in with the roots hitting the bottom of your cup because you dont want the chance for the roots to grow out the drain holes
so put some soil in the bottom first then put your seedling back in
position your seedling at desired height for your stem to be buried at
i would bury all the way up to the Cotyledon leaves ,
after your have replanted and buried your stem you can then give it just A LITTLE bit of water
the part of the stem that you buried will eventually start to grow roots
your plant will pretty much not go into shock at all from this
just make sure your gentle when your braking the lose soil off the roots
Like i said this is not a bad stretchy plant but the same principle applies with those long ass stretchy stems
hope this helps you all that has the long stretchy seedling stem problem
remember to lower your lights so they wont continue to stretch