Odd Yellowing Top Leaves

Alright I've had my first plant problem and am hoping one of you might help me out. I've noticed on a couple of my plants the top leaves are starting to get a rather odd look; see pictures. These are outdoor plants in pots, bag seeds. Any ideas are greatly appreciated.

NIP

sre you feeding them any nutes?

What are they growing in?

They are growing in a pot of soil. The mix is of perlite, top soil, and peat moss. I added nutes once which was miracle grow, simply because thats all i had. After i used it they showed signs of burn so i decided to not use it again and have been waiting to get better stuff.

NIP

Any ideas?