I agree, the lily requires ericaceous soil, and I add grit and multi-purpose as I find straight ericaceous clammy and not fluffy enough.
Given this, if you don't have the right pH, it is best grown in a pot as it will die in alkaline soil over a couple of years. Cool roots and head in the sun, but 100F is asking too much of it and certainly the advice given above is helpful.
Worth the effort. In some the colouring and speckling is more coarse than others. The example you photographed almost has colour in the gold band. I think I have seen this before but not on L.Auratum. I'll have a scout around.
Regards,
Peter
