No practice greens per se...what you can do is play practice rounds and putt around on the greens...you should be able to hit 8 or 9 putts (if the ball does not go in the hole) before you reaching the maximum strokes allowed.
Joey
^ Joeyola has told you about only option for now. Works for other shots too.
MrNASCAR29:My putting is killing me.Is there somewhere on here were I can practice putting only?
If you haven't read it look at WGTNiv's Putting Tips in the FAQs. He lays out a method, with pics, on how you can fine tune your putter.
MrNASCAR29: