Yellowing Leaves on D. anosmum in the dead of summer

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That's more a bract than a leaf. It happens to all bracts as growths mature. I wouldn't worry about it.

I agree you could probably grow this plant outside almost all year in bright to dappled shade. Mine has experienced 100+ F / 38C days without any problems. You would need to water plentifully during hot weather. I bring my plant inside during our summer heat, and put it outside when nights are cooling. I leave it out all winter except on frosty nights. I bring it in when days start getting hot.

I don't recall whether San Antonio gets frost. This plant can tolerate temperatures all the way down to freezing, and some people say a few degrees below.