fiat: Usually with the double pot method, the bottom pot has no drainage and acts as a reservoir to hold the water. The second smaller pot (with the plant) sits inside the "reservoir pot" with a wick trailing down through the soil and out the drain hole. The wick draws up water to the plant as needed. I've known people who've used nylon twine for plant wicks as well as yarn and nylon stockings cut into strips. When I grew AV's I tried the nylon stocking strips but they drew up way too much water and I found the soil staying too soggy, causing rot.
Some folks like to use just regular shallow plastic pots for their AV's and they place a piece of felt in the bottom of a rectangular tray and sit the pots on top of the felt. Water is added to the tray to keep the felt moist and the capillary action draws water up into the soil.
You can read more about self-watering pots here at the Optimara site:
http://www.optimara.com/selfwa...
