I have been planting mine the same for many years now...
On depth (on average 3/4 to 1\" deep)... in softer loam or sandy soil deeper, in clay shallower.
In October 2009 me and my boy took a little hike down to the waterfall out back and there were a couple of pale yellow 3 prongs on the bank there that had a few red berries left.
We collected the berries and harvested the roots and I showed him how to do all of that.
Planted those berries back right there where we harvested the parent plants.
On April 21 2011 we made another trip to the waterfall and checked out the results... (see below).
Notice that some of them came up in pairs - for those both seeds from the berry actually germinated and sprouted.
I have been hunting these hollows for many years now... and I always plant my berries in a row/trench... and when you go back a couple years later you have all of these 3 leafers growing in a nice straight row. Then 6-8 years later you will have a nice string of 3 prongs all growing in a straight row.
It's a cool thing to see work out but does take some time.
TNhunter