Here in Victoria, Australia we have some fiercely hot Summer and cold wet Winters. I tend to keep the rhizomes as uncovered as possible during the wet months to minimise rot. Even so, I still lose a few. In Midsummer I let a light covering of soil cover them to avoid them being scorched. I live fairly close to Barry Blyth's farm, and their rhizomes are very near the surface. I believe that it just depends on the local climate whether you cover them or not. That's just my opinion rhough.
