Just wondering, since it looks like theyre stretching more than growing for 18 days, whats your light setup? The aluminum foil might not be ideal either, if youre wondering
Either the light is not strong enough or not close enough. On you next grow or when you transplant the ones in the smaller containers I suggest adding a lot more perlite to your soil mix. Good luck.
And try using fabric pots. They drain better and air prune the roots which will prevent your plants from becoming root-bound. And they are just better in general lol “Tyranny anywhere is a threat to freedom everywhere.” — someone awesome
I was using halogen lights I know they stretched and halogen are terrible but now I got a t5 fixture and I hang it close to the plants