Aspirin is a remedy for fungal plant problems (black spot, powdery mildew, and rust are a terrible trio of fungi). Dissolve two uncoated aspirin tablets milligrams each) in 1 quart of water and use as a foliar spray to thwart these diseases.
How to make a Sub-Irrigated Planter. I'm not sure I would use a two liter plastic bottle though. Over time I would fear the plastic breaking down enough to poison the plant. Perhaps a wine bottle instead.