PP Help?

[Turnerea]

I've learned enough about PP (I use Gimp) to stitch panoramas together relatively well, but I have a more extensive PP project which I've tried and failed at numerous times.

I'd like to take the grass out on the left, and possibly even the building just above the grass horizon. I tried my hand at using the clone tool, and copying parts of the right side over to the left and trying to mesh it back in..... but to no avail.

What would you do here? If anyone is so inclined, feel free to do it and post it back here, but what I'm more interested in is the strategy required to get this done.

Thanks!

ISO 100, 1/125s, f/9, 35mm

 

[Samanax]

In case you didn't know about this web tutorial - Grokking The GIMP