Bill, there is no stand alone spice/herb forum. Typically, spice herb questions appear in the forum appropriate for the dish that's being prepared. For example, seasoning a pasta sauce or stew.
Otherwise, they would fit into the Misc or General forums.
What types of spice/herb questions do you envision in such a new forum?
"If you want to make an apple pie from scratch, you must first create the universe." -Carl Sagan