Have only been gardening a year or two. I live in Northern VA (USDA Zone 7a, if that helps) and recently bought a "Kentucky Colonel" spearmint plant at my local garden center and transplanted to a pot. I had used up all my pots with holes and new mint didn't mind wet soil as much as other plants, so i filled the bottom of the pot with rocks for drainage then added soil and planted the mint. I keep them on our back deck, which, I believe gets a strong Northwest exposure. A few times when the rain was heaviest, i'd tip the pots that didn't have drainage holes to empty excess water. The past week or two the sun's been stronger, so I moved the mint to a place where it still gets sun, but gets shade earlier. A slight green moss has grown over the top of the soil and today when i got home i noticed several of the bottom leaves and a couple of the stems turning brown/black. Any ideas what I can do to remedy? I'm probably giving way too much information for this little problem but I don't know much about gardening so want to give as much info as possible.