I would suggest that the problem is not with your heat and humidity, since your fall and winters are not so much different than ours here in NE Mississippi, but with your drainage. Garlic just hates "wet-feet", the same thing I tell folks about my epiphytic plants (think orchids), so great drainage is so important. Heck, my raised garden started at 12-16" deep and is notw18-24" deep. Thus I have raised my garden two feet above that horrible clay foundation that I live on. Large pots more than satisfy that situation as well and are a lot less expensive than building up a raised garden. I have just started using Earth Boxes and don't know whether they are good to grow garlic in.
