How to overlap an object - ie - petals of a flower (with pictures)

Hey Guys, 

I'm looking to fix this issue which im sure has a relatively simple remedy, but i just don't know what to type into youtube to find out. 

When adding petals and maunually rotating them (as opposed to duplicating them around a path) the last petal sits on top of the others. What I want this half of the petal marked out in green to look like the half marked in blue.  

Any suggestions? 

Much appreciated