Ron,
regarding my previous #4.:
I don't know if you just started with panoramic stitching of if you have done this for years already but with the current software that's out there and I'm sure also with the software that you used you can stitch an (almost) infinite number of images together (until you run out of memory).
My Canon has a stitching setting but the Panasonic does not & that is what I used.
I know you "only" took 6 shots from left to right but my suggestion was to add another 6 shots above the ones you took also overlapping the previous ones to get more of the sky. Maybe that's clearer now.
Now I understand.
I assumed that all settings on your camera were locked. I'm not familiar with your camera body so I can't tell you what Av mode does but all settings need to be on manual. What you did with the lens, setting it to manual aperture is absolutely the best thing to do because the blades will always stay in the same position instead of using a "cheap" lens that won't allow manual aperture. In that case the blades will NEVER open precisely the same amount in each shot and you will have brightness variations which is really something you want to avoid.
In "A" mode the camera selects a shutter speed & that is likely why I got uneven exposures. Thanks to the input from folk in this thread I now know better. I think I will use a hand-held light meter next time & set the camera up in "M".
Nice property but I feel for you when it comes to "gardening"