Ok, i have returned. Mint loves attention, but does best with hard times and abuse- like a weed. Poorer soil brings out its flavors more intensely, the constant cropping sends roots DEEPER, makes them stronger. All plants wilt in the heat and sun. It is a survival trait to withdraw moisture into the roots, then with the sun setting, the plant perks up once again. You might help it thru the changes, Not with water, but with a few hours of shade during the time the sun is strongest.
Good luck!
