Such. A. Fabulous. Idea! During one of my herbal apprenticeship classes our teacher devised a mini greenhouse from an old 1 gallon plastic jug to grow her goldenrod seeds in.
I mean the science behind this greenhouse concept is truly amazing considering that you are paying nothing to get the wondrous affects of a greenhouse - insulation, heat, moisture, protection from harsh sun rays that can burn your little seed babies. She cut it out in the middle so you can put the soil in it; took the cap off the bottle so it can have air, circulation and some filtered sun...and wallah! Goldenrod seeds popping up in half the time.
I tried the same technique but with using old plastic spinach containers.
I made sure to puncture some holes through the top and bottom so there would be good drainage and also air circulation. I planted about ten seed pods per box and made sure the soil was moist at all times (it mostly stays moist by itself because of the humidification affect). I kept the top on and the boxes got about 6 hours of sun a day. I ended up planting calendula, luffa/gourd, and chamomile which all sprouts about 3-5 DAYS earlier than normal and grew/outgrew their little greenhouses really fast. The best part about this is that the plastic boxes are reusable, I washed mine out and set it aside until it's fall planting season.