root stuning

ok so i have a plant that is a month and a half long and it started to show some brown color on the tips which lead to the whole leaf turning that color and i had to cut it of. i thought that was normal since it was the fan leaves but now the leaves that come after the fan leaves are showing the same problem and i dont wanna cut them down... i read what the problems could be and it seem to me is root stunning ... any help with this?