my problem is during the winter I have to bring these inside and they are put in a back bedroom and almost forgotten about.  It may be two months... in the past it has been... before they get a drink.  They don't tend to do real well lie that.  But outdoors during the summer they get lots of rain and seem to do pretty well.  I had one in my kitchen window and drowned it though.  But your idea just seems like the perfect babysitter.

Perhaps I can try different types of cloth or widths to try and determine what one carries more or less water.  I have about six of these so I may have to turn the whole thing into a lab experiment.