Tomato leaves drying

[snagfinder]

Just curious if anyone could help me with what to do. Started my tomatos a month or so ago i know it was to early but anyway they are about 9 inches tall and the tips of the leaves are drying up. I used a starter kit that swells up with water looks like a nylon. Thinkng it could be cause roots are sticking through and exposed to air and light. Usually use those peet pots and never had an issue before. This year also using grow lights for first time dont know if that could have an effect.

[terrywatkins]

Whenever this issue arises my friend used to sprinkle some chemicals on it.