If you want to do a foliage scene, it's not bad to do the tutorial first, since as far as I know it's a fairly standard and generic way to make foliage. I'd say, just make sure after you done it, to grab a couple of references of trees you like, and just make a set of trees/flowers/plants that weren't done in the tutorial.…
I want to do more organic stuff, just want to be sure I show what im good at first. I do have some tree's but I referenced the 3d motive tree tutorial a lot and I don't think having something done along with a tutorial would be good for a portfolio.