Well, we did end up losing the calla lily, and the mint didn't make it either. But, it looks like everything else is hanging in there so far. We might even get a tomato or two. I added 4 bags of mulch a couple weeks ago, and hopefully that will help retain the moisture. Fingers crossed we'll all make it to rainy season, especially since I won't feel much like watering at that point!
The front patch, on the other hand, could take over the sidewalk pretty soon! I think I'll take out the smaller, slower-growing plans and just let the other two enjoy the whole box.