David,
>> My current thought is to use a "sham-wow" which really absorbs water, draped over both ends of a 1" thick block of styrofoam sized to fit the tray ... and as water was absorbed the styrofoam would drop.
That sounds like a neat idea. It is a way to keep the exact same height between the water surface and the soil surface, even as the water drops.
Visualizing it, I wonder if the floating support would be "tippy" like a raft. I don't see any reason to mind if it drifts back and forth an inch or so, and sideways motion could be prevented with shims, but the idea of "tipping" makes me a little nervous. I think that might be for no good reason. I doubt if the "raft" could tip enough to make pots tip over, and a plug tray would be totally stable even if the Styrofoam did a jig. It would probably be good for the seedlings: increase air circulation and strengthen their stems!
Hey, it would tell you very clearly which rows were growing faster than other rows, by tilting towards whichever side grows foliage fastest!
P.S. Several people have suggested finding "Sham-Wow" fabric for wicks. Do they have any kind of coating or starchy filler? I have no idea, I just haven't ever had one in my hand. Probably they have some "microfiber" content, which sounds perfect for a wick.
Danita,
I like the idea of using fluorescent light diffusers as a support to give a larger reservoir! Hmm, 4 for $13 ... $3.25 each ... I would shop for used ones at a Habitat for Humanity Restore.
But I don't often go away for as long as I did recently! When I used only the grooves in the trays plus the thick mat's "sogginess" as a reservoir, small seedlings lasted 2-3 days without watering.
