I grow Tumeric in Florida (zone 9B) and I grow them under pine trees so it's semi-shaded & naturally pine needle mulched. Mine do not mind sandy soil but they do at times get brown leaves and look kinda sick then suddenly they perk up again. I just sprinkle Black Cow around them once a couple of months.

I've grown them for 4 years and harvest the rhizomes (leaving 50% undisturbed) twice a year, usually around mid-spring and early fall. I try to leave some rhizome & most fiber roots intact then re-plant the uprooted plants. After harvest I clean & cut the rhizome into portion-size & freeze.

So Turmeric can overwinter?

Yes, but to my knowledge, in zone 9. The leaves may turn brown & even "disappear" for a while but come spring, new shoots will emerge.