The problem may be with how color is used and not with any single color choice. This link will take you to a post that states it much better than I could:
May I Ask A Favor?.......
Maybe I could use a different shade of green.
If it helps, main topics have a lighter background color and then alternate between darker and lighter colors. In an established topic, you can find out if any new posts have been added by using the preview feature before submitting your post. It's still possible for a post to be submitted a split second before yours, so it's a good idea to look over your post (you can set your Look and Layout preference [in your profile] to return to the topic after posting) in case you want to click the modify button and edit your color choice.
However, it's very possible that the current color scheme of the forums will change, AND that themes may at some point vary individually.
All that having been said, here's a suggestion for a green against posts with a lighter background:
This is darkgreen in size 4.