this may sound silly but i saw on tv this glass blown globe with a stem, basically you fill the globe up with water, you then bury the stem in the soil the way it work as the soil dries it realeses oxygen airbubbles up the stem and into the globe which then releases water slowely it supposed to be the perfect amount of water for any plant i think it sells for 5-10 bucks and it waters without refilling for 2 weeks. damn i wish i remember what it was called i just saw this last week. ill try to see if i can find it