You can use many types of containers, if you click on the winter sowing forum you'll find all types of ideas for what you can use. I found that foil pans are fairly cheap and reusable and take up little storage space. I learned a few tricks to prevent the mess I made the first time. I lined a couple of large cookie sheets with paper towels to absorb the muddy water that leaks through the bottom of the pans.
Probably most people would use a bucket full of potting soil and a shovel to mix the water in with rather than a large mixing bowl and spoon, but since all that stuff was outside and covered in dirt I used what I could find inside, besides isn't this a better use? Maybe that's because I'm not much of a cook?
There are holes punched through the bottoms of all these pans so that the muddy soil can drain. I fill them just about to the top, the soil is pretty wet.
Because I don't need huge amounts of plants I use half a pan for each type of seed. This year rather than trying to use tape to write names on each pan I just numbered the sides and lids and wrote the name of the seed on a piece of paper. I try to be sure to put seeds that will have different looking leaves from the one they share the pan with so I can tell which is which later on. The Columbine seeds are from Alison at Bonney Lassie and the Brunnera are from Lona at A Hocking Hills Garden.
I just sprinkle the seeds right on top, maybe pat them down just a little.
The plastic lids have holes punched in so that rain can moisten the soil. They will sit on the deck for the rest of winter and be transplanted after the last chance of frost. Some seeds germinate quickly while others seem like they never will and then surprise me right after I threaten them with the compost bin.
I will do more winter sowing in a few weeks and wait even longer to winter sow annuals since most of them seem to sprout quickly. There is a Facebook page for the winter sowers group that also has lots of information on it.
It feels so good to have started the first seeds of the season. Now I look forward to seeing blooms!