I have a blog post about a recent backpacking trip that I went on, which I would think would be of interest to multiple communities on Google+, such as the outdoor adventure community, the backpacking community, and Southern California hiking communities. Unfortunately, Google+ only allows you to to share a post with one group at a time, which is mildly annoying.
I solved this by just resharing my original post — so for instance, the first share of my blog post I just shared publicly, and then I reshared that with the various groups that I wanted to share it with. It seems like there is some discussion about whether this is a good practice or not. I think I\’ll just plan on using it sparingly and only ever share a post with a few communities.
This did cause a minor annoyance on my google+ posts page — the same post was appearing a couple times, since I shared it twice. To stop this from happening, go to the settings page (https://plus.google.com/settings), scroll down to the "Profile" section, and then uncheck the box next to "Show your Google+ communities posts on the Posts tab of your Google+ profile.". This should keep your post and reshare from appearing twice.