How to make my bf stop smoking weed or at least cut back?

I've been with my bf for 8 years now, he's been smoking since he's 15 (he's now 29) I didn't really m ind it at first but now we bought a house, have an 8 month old baby and are getting married next summer. He smokes way to much, it's the first thing he does when he wakes up in the morning. How could I make him cut back a little, I don't want to raise a child like this...plz help! only serious answers please.