Vacationers' houseplants can water themselves with the aid of gravity and a wick.
Martha Stewart Living, August 2001
cut a piece of nylon clothesline long enough to connect water source to plant. Soak rope for 30 minutes; water and drain plant thoroughly.
Place one end of the wet rope in water container; push the other 1/3 of the way into soil (below). Then, raise container on an inverted pot so it is higher than the potted plant. Use more than one wick for extra-large pots. To set up a system for more than one plant, place individual wicks in a generous water source, such as a garden pail.