Here is one dark color that works well with green. Of course, this is a wooded setting without the unsightly buildingscape I have surrounding my new garden. Will a color like this highlight the very view I want to de-emphasize? I like this effect, though I'd prefer a color with more gray/charcoal and less green. This is a rather dark color, but it has a surprisingly reflective surface, which increases the contrast with the dark green foliage of the plants.
Here's another similar color, but with more green. I prefer something closer to charcoal or gray.
Now this appears to be a black fence with a very flat, reflective surface. I definitely don't want this.
This putty gray color isn't bad. Not my preference right now, but something in this family may be an option. It would blend well with the surrounding building colors, and might make them less obvious.
I think the next step is to get samples and paint them on for an in situ test.
I've started a garden fence board on Pinterest (link on right side of this blog). If you have other examples, please let me know.