What do I do wrong?

[Sirtastic]

I've got 2 54 l tanks, 1 with normal gravel and the other one with something more like sand/gravel, this one has nutriens in it. But my plants dont look good. They have been in the tanks for like 2 weeks. I dose iron every week.
Sand/gravel

Gravel

 

[Bert2oo1]

Plants don't just need iron. You should be dosing both seachem flourish and seachem flourish excel. Also would hurt to be dosing seachem trace aswell. I'd go out and buy all of those and dose to recommended

 

[Fresh2o]

What is the height of the tank and what kind of lighting are you using?