I usually keep my containers in the sun until they have sprouted and then decide what to do with them depending on weather and the type of plant. I remove the tops of the containers ASAP to avoid frying in the sun, and throw a sheet over the whole mess if frost threatens and I have tender sprouts.

Martha

I agree with Martha, in the sun and where your neighbor's won't complain.

Alright :) I just didn't wanna fry them :p (don't care about what the people beside me say they are plant people on one side and know I'm odd on the other) thanks :-)

I have mine on the sunny south side of my house. I have three of those little pop up greenhouses side by side up against my porch railing. I tie the greenhouses to the railing to make sure they don't get blown over or anything.
Right now I only have 8 kitty litter jugs on the top rack, but soon that will be filled with 16 more jugs.. then two shelves down I will be filling with milk jugs.

Beesneeds, why do you have them in greenhouses?