Tazman...
I think it depends on how far north or south you are. For example New York / Maine, vs Tennessee / Alabama.
Down here in southern middle TN, you just will not find it on hillsides that get too much towards the west or south.
North facing hillsides are best... and between due north and North East are Ok (anywhere from due north to north east) but on the average slope, when you get too far towards the east closer to due east it just will not grow (with one exception) which is very steep hillsides like bluffs that face due east.
Once the hill side starts turning a little south or west... you are just walking and not going to find any seng.
I am sure that applies to Alabama (even more than TN), and probably more so in west TN than in Middle TN.
Mountains may make a difference... keep in mind I don't have mountains here in Middle TN, just hills and hollows.
I think there is a point as you get in the more southern states where the north to north east thing absolutely does apply.
Not sure exactly where that is, but it is very true for my location.
Down here west and south facing hillsides are just TOO hot for seng. Most other companion plants and any soft green plants just do not exist on south or west hillsides either. Too hot for them too.
TNhunter