Growing mint and lavender in humid and hot area

[TessV]

I've had almost no success with lavender, but I absolutely adore it. I've tried grosso, Munstead, and Spanish lavender and all have died as soon as the rainy season started. I've tried containers and adding a lot of shgarp sand to help with drainage, but my plants still rot.

The same thing has happened with all of the mint varieties I've tried; I can keep them alive from about December to late May, then they start looking ragged. By July they're dead. I know it's best to just accept your climate and grow what's suited for your yard, but I desperately want to grow these two plants. Does anyone have any tips or tricks, please?