I think there are 13 episodes in season five. Not sure though.
And we get season six as well.
The first episode I saw on Showtime is episode one of season five. We got Showtime. And I randomly clicked on that channel, and you get the super funny scene where Nancy is telling Esteban that she's pregnant so he can't kill her. And basically one of the bad guys shoots the other two in the same room, and Nancy is like, "well, I think I have to go."
Just a funny introduction!
By the way, this first scene is so funny because you see a jealous Nancy:
YouTube - Weeds - Nancy & Andy - 5x04
The way she is going off about Andy sleeping with her sister.