It sounds like a really nice idea, especially if you're not using the garage. I would be concerned about things touching gas or grease stains on the floor but is it really stinky? What were you thinking about covering it with? You of course wouldn't be able to get permeated stains out but if you do a great surface cleaning, it seems like a garage floor is likely a flat surface that could be easy to cover.

Thanks for your response, christinela! I was wondering if anyone else here has tried to garden-ify a parking lot or garage :) I think ideally I would bust up and remove the old concrete floor, stained almost black with grime, but I'm neither young or rich enough for this job. The garage floor isn't flat. It's eroded. Well, maybe not that badly. I would probably be satisfied with pavers set in gravelly sand. I can imagine the structure transformed by vines, moss, etc. I wonder if it won't cost me very much to have the roof removed because the material is reusable. Maybe I could leave the rafters in place and paint/weather-proof them? Maybe it's better to just give them away to whoever is willing to remove them. The garage has no electricity supplied to it, so that's not a concern. I believe I need to mortar closed the tops of the walls, but I could leave the block bare, not paint it since it never was painted. One exterior wall currently has English ivy covering it, yes, an invasive plant, but it is there already. :) I imagine filling in most of the front doors space with lattice and container vines. My asphalt driveway comes all the way up to the doors. I'll also mention here that the house is rustic rough hewn fieldstone, the property rustic looking in general, so that an old garage that became a courtyard wouldn't look out of place.