I've dug some nice roots at 0-500' on up to 2300'. Soil and light, moist and cool is what I key on. Then just when I think I've got it figured out, I find a spot like I did last year with 12 roots over 2oz each, 4 of which were over 4oz each, one 5.7oz. All in one little patch, west facing, top of a mountain at about 2000', mixed in through a rock slide, ..... but the nicest, fluffy black soil you ever did see! Go figure!