Please help diagnose what's wrong - Yellow bits

[callmelizzy]

Hello – new grower here. I have 5 plants, all very young. 4 are lovely and green and the 5th is showing signs of yellow on the tops of its leaves and the lower leaves are all yellow. At first i thought it was nitrogen deficiency yet now thinking it could be something else.
Thanks in advance for your replies

 

[Richard Richardson]

Epsom salts

 

[Emilya Green]

two things come to mind...

possibly rootbound... that is a lot of plant in that little container

possibly improper watering. Are you letting her dry out all the way to the bottom each time between waterings?