There are limitations to what you can grow using this method but I'd say that is limited more to tropicals or temperature sensitive plants. I grow mostly tomatoes, peppers, perennials and hardy annuals using my pots outside.
I use my husband's soldering iron to burn the holes and then cut the containers about 3/4's of the way up. Plant the seeds in the potting soil (anything cheap will do), tape the tops back down and leave the screw caps off for air and water to get in. Stick, them in a sunny spot in my backyard and wait for sprouts around March/April. I live in zone 7B.
I'm not good with html code but here's a good website with more info about this technique. http://www.wintersown.org/ I've been doing this for about 3yrs now. I now only grows heirloom tomatoes since I can finally grow them myself. I never had luck with indoor planting, unfortunately. Too many curious kids, dogs, not enough space and my own incompetence. lol
That sounds like a wonderful idea. I might try that myself starting in March and see what happens. Since I have no way to recycle my milk jugs anyway, this will be a good use of them.
I’m in Zone 5B. Just a little west (1-2 miles) of Lake Michigan.