I've been looking around the net for a tutorial on how to make your own plants, but I dont seem to find any. I tried using the Start to Finish Object Creation Tutorial by J.Woods. But I screw up at the UVmapping part, which ever UVMap I use (box, cylindrical etc.) none of them seem to look right. Which makes it impossible to work with in Photoshop.

Does anyone know of any tutorials about this or maybe have any tips on how to succeed?

Try taking a look at some existing plants - Maxis and custom, to see how they're made.

I think in most cases you will find that the pieces are various types of planes (which may be curved/manipulated/shaped), mapped flat, then arranged repeating through the plant. Edges of the textures will have alpha cutouts (transparency) to create the illusion that half a sphere really has edges that make it look like the petals of a flower, or that a simple diamond-shaped plane has a gently sweeping curved and serrated edge, like the edge of a leaf.

You'll see more specific examples and techniques when you look at some existing plants and pick apart what their creators have done to make what you see in terms of mesh parts, mapping, and texturing.

Okay, thank you very much. I'll try that and see if I can figure it out