I read about someone (I can't remember who) putting their seedlings into kiddie wading pools.
I have limited room for my seedlings (and not a whole lot of sun), so what I did last year was to get some plastic boxes, about 5-6" deep (the type used for clothes storage and such - you can get them at the hardware store). I potted my seedlings up into
9.5" high tree pots, and put 20 of these seedlings into one box, which got placed on my patio edge (one of the sunniest spots on the property). There was water in the bottom of the box all year (I would occasionally water it, and/or add some fertilizer), including the winter. (We are zone 9 here; although we had several days of frost and lots of dead plants this past winter, I don't know if the water in the box ever froze.)
I am happy to say that those seedlings have THRIVED! I hope to see bloom this season.
Re mosquitoes - yes, I found a whole bunch of babies
last week in a second box of seedlings which I am slowly filling. I poured in a little Dawn detergent (it was that or try olive oil - those were the two things I had at hand) onto the water, and the next day there were no more wriggling larvae. (I haven't noticed any negative effect on the seedlings from this, though I should probably keep an eye on them.)
One other hazard I should mention, though, is that I have had slugs and snails somehow get into the boxes. Sluggo in the pots is probably a good idea; I sprinkled in some of that last week, too. (I also once found one of our native frogs - very tiny critters - in the box, nestled way down between the tree pots. I have no idea how it got in there.
Maybe it was doing slug and snail patrol for me?)
Edit: I just checked on the tree pot size, as I had second thoughts and realized that 8" (as I originally wrote) seemed too short. They are in fact the Stuewe TP49 pots http://www.stuewe.com/products..., which are 4" x 9.5" and have a volume of around 0.44 gal (based on the data when I bought them). Sorry for that error!
