Hi Chris..I'm a third year wintersower, from Ontario (Oakville), and I'd be happy to address your questions.

1.Lids are important to keep in the original moisture you add when sowing your seeds, plus, condensation and natural rainfall, or snow, approximates natural conditions for germination. (Mesh won't cut it, because the condensation does most of the watering).

2.The lid is not closed off to whatever snow or rain may fall on it,(open 2 litre bottles, milk jugs, slitted lettuce containers, etc.) so yes, moisture is required. The light they require is the same light that any seeds need to germinate...perennials need it throughout the winter, to aid in the striation (warm/cold) to germinate..annuals need it in April (in my zone).They need to be outside, not in the garage.

3. Yup, many seeds volunteer, but if you want robust seedlings that you can plant where YOU want them in the garden, and plant early in the spring (getting a great head start on sowing seeds after the "24") then this is definitely the way to go.

Please check out Trudi's (our Yoda's) site at wintersown.org. So much information..all your questions will be answered.

The lids hold in moisture, and they also create warmer air inside the lid when the sun strikes the plastic. They make the container into a mini-greenhouse. The containers are warmer than the surrounding air, the air is moist, and the seeds sprout sooner and have better growing conditions than outside the mini-greenhouse. With perennials, subsequent cold weather is not a problem--they just grow when conditions are good, and hunker down in the cold weather. With annuals, there is a risk that a warm spell will sprout them, and then the weather will get bad enough to kill them off. Frost won't necessarily do it, as the containers retain some heat through the night, it depends on how cold the weather is and for how long. Not every seed sprouts at once, so there are usually some seeds left in the dirt, and they will sprout at a later time--so a person would probably have seedlings of that plant even if some early-sprouters were killed. But that's the reason a lot of wintersowers choose to put out perennials first, then put the annuals out closer to plant-put time. Annuals grow really fast, perennials don't, plus many perennials need that cold-stratification. Trudi advocates a tough-love treatment of our containers when weather gets bad and annuals might be lost, but no police show up at your door if you cover the containers with a blanket or bring them in for the night!

If you had your containers in a garage, they likely wouldn't get the light needed to sprout. The sun really warms up the containers--remember, mini-greenhouses--and some seeds DO need light to germinate. Then, once they germinate, they really need good sunlight for photosynthesis. Wintersowing gets the seed-starting out of our houses, and the mini-greenhouses give us seedlings that are bigger than if we just direct-sowed or didn't have the added warmth and moisture given by the lid.

You asked about just keeping the seeds cold, in the packet; that won't break down the dormancy of the seed. It needs to be in contact with moisture, too. Before starting with wintersowing, some of us would do that by sowing a pack of cells, and putting it into the fridge and freezer. It's nice to not have dirt in my fridge!

I hope my extra info has added to your understanding of why we do what we do. And, Trudi, if I garbled anything up, sorry!