Whats wrong with my plants?

Can anybody tell me what is wrong with my plants? I'm growing outside a WW and Blue Cheese strain and then i started noticing that the leaves were turning yellow and falling off.

What scroglodyte said

Best way to grow weed is to only ever do half of the stuff you think that she needs.

Thinking of watering, just cos you're worried she's thirsty? Don't...dry plants are very easy to spot, and will recover within an hour of a watering. If you over water on the other hand then you might have days of weird symptoms before you fix it.
Thinking of pumping your plant so full of nutes the THC burst out of her? Think again. A plant will only ever use as much as she needs. Plants aren't greedy in that way like humans. If you give her more than she's using you'll end up with major problems. If you give her too little, chances are you'll see very obvious yellowing (N deficiency) and you can use that to tell you that it's time to give more.

Less is more, because more appears to kill plants more often than less. (for a new grower particularly)

Edit: Just saw your last post. You shouldn't be adding nutes at this stage. OF has nutes in it already doesn't it? Certainly plenty for the first 3-4 weeks.