Wind is a big problem with bottles screwed into the ground. Frezing and thawing loosen the bottle from the soil and away it blows.

Also, when can you should you plant the seeds out that you want to winter sow?

WINTER

Here is a link that might be useful: WinterSown.Org

Well, just how much snow do you get there in zone 4? It seems to me that your proposal of sowing the seed on the bare dirt and then putting the bottle over it (technically called a cloche) would only work if you have no snow on the ground.

One of the nice things about winter sowing is that we can sow seeds in the middle of a blizzard. It sounds like for your idea to work you would have to wait till spring to sow, when your snow has melted. If you do that, anything that needs cold to germinate will fail. Or you could plant in late fall, before snow starts to fly, which could result in your seeds frying if you have an autumn heat wave.

Plus, winter sown seedlings (honest, honest, believe me!) seldom, I might even dare to say never, suffer transplant shock. And if you sow them in paper pots or toilet paper rolls, you can plant the whole thing in the ground without disturbing the roots at all.

One thing I do to avoid the problem of drying out and inconsistent watering, is I set the winter sown containers in plastic trays with holes drilled about an inch up the sides for drainage, so they get bottom water when I don't have enough time to water them every day.

Hope this advice helps!