My own experience with these little gems, is that, yes, they are fussy. I have only seen them on hillsides or steep inclines, in clay, or gravelly clay with minimal humus,(less than 3% probably) and 6" down is not unusual. This is clearly not to protect them from cold, but from summer heat, I suspect. If you can grow oncocycli, you can probably do well with these, if you have the climate for it. Occasional summer rain even heavy rain is OK, but drainage must be "sharp". They would appear to be good rock-gardening subjects. Adam in Glenview, il