What Kind of soil, Lights,RH, PPms,Neuts, if you know them. It will help get the right advice for you.
To me it may be to dry maybe? but that is just a guess not knowing what you are using.
Pictures of the top of your lady will help too.
Also make sure it isn't root bound,
There are so many things that can affect your girl, More info and pics will help people here identify your issue's
Good luck Hope you get it all figured out.
BTW Welcome to RIU