Baking Maps - Alpha

Hey’all, got a question =D

I’m creating foliage and wish to bake it to a simple plane as you usually do. Problem is that it doesn’t add the background to alpha. I’ve been searching for answers but I’m not sure if this really isn’t possible? I know blender doesn’t like baking other transparent materials, 3dsmax have the same problem. These are meshes tho.

What I also find strange is that it can add padding around the edges of the meshes (something you usually disable of cause), so I would assume getting the transparent background into the alpha wouldn’t be a problem?

Here’s a img of the setup. A baking plane + grass meshes.

Any ideas?