OK!
It's not a lack of N.
Worm castings will supply plenty
Perhaps too much at that tender age?

Worm castings can make the soil hold water too.
The tip browning w/curl, looks like wet feet to me.
Let her get good and dry.
And not just "surface dry"

Best way to check, is the "lift the pot" method.
Every time you look in on the girls, lift each pot.
When it gets nearly as light as a similar pot filled with dry soil, it's time to water again.

You might as well get serious about your first grow.
I'm willing to bet, it won't be your last.

Aloha,
Weeze