You can start any time, just like mother nature would, BUT I usually start mine once the snow starts to fly. I don't have enough time before that. So December is good, or January, or February. Some seeds need a longer cold period, so that should be taken into consideration. Check out the winter sowing forum on the garden web. There is a lot of good information there,....especially Trudy, whom I believe founded the movement.

You can also check out the Canadian Winter Sowing Forum. One of the posts there is concerning when to start.

Here is a link that might be useful: Canadian Winter Sowing Forum.

I prep my containers now (I use those large 10 litre water jugs cut on their sides to allow more room to grow things in, and actually recycle about 75% of the previous years jugs that survived the cold without cracking too much) and fill with soil outside (where the mess still can be hosed down). Then I bring them down to the cellar to wait until the week after New Years, when I can concentrate on exactly what I want each jugs to contain, and then I plunk those jugs back outside until spring.

One year I started too late and it took ages for the bags of soil to thaw indoors - I had left the bags of soil in a pile outside, and because of the rains & subsequent freezing, the job of even trying to separate the pile of bags from each other was an adventure I don't want to repeat. The bottom bag never did get used as it was frozen to the concrete.

Best wishes.

Thanks for the good feedback. I'm moving and will have to create a new garden from scratch once more (dare I say, yeepee)