Plz help. Switching soils on three week old plants w/pics

I have three week old plants that are on the small side because ive used mg soil on some, and dirt from outside on others. and are growing very slowly. the pic is them at three weeks.

i want to switch to an organic mix. whats a link or recipe for a basic starters organic soil that i could make from basic stores.

3 weeks? Really?

Try FoxFarms.... Here's mine right now that are only 2.5 weeks.. I started them in Jiffy seed starter soil mix and then transplanted into the FF after about a week..

Normally I would call BS and say there's no way those seedlings are 3 weeks, unless you are counting the time the seeds were planted in the dirt? But I know MG soil sucks and way too hot for seedlings.

Man believe me I wish you could call Bs on this. They sprouted after about 4-5 days in the humidity dome. This is them three weeks after that

I was looking for more of a mix I could make from home depot, or lowes. Or something of the such. I dont have any shops around me, and would like to know an organic mixture i could make at home. Do you know how to make the one containing spaghum moss, perlite ?