Beginner grower

[LovelyJuva]

What is going on with my plants??? I have a total of 7 plants actually 8 I doubled up one which is doing well. This is also my first grow and I really don't know what I'm doing. I took everything I learned from my research online and know I'm stumped. Buddy is the baby which is 5 weeks wilting and bottom leaf yellowing. Juicy 6 weeks today had a nut burn still growing but still not looking healthy as it was ( no photo.see previous post). Santana 6 weeks today canoeing under and bottom leaf yellowing I have been having problems with this one since I started. Chico 6 weeks today is the biggest has a brown spot on one leaf started two days ago.

[TheDude777]

I took a look at your pics but I couldn't see how big the pot was. It could be that you need to transplant.. Are you checking PH ??? You can get test kits for cheap at Wally World. $3ish