My sweet friend Amanda is saving her filtered water jugs for me to use. You can use all kinds of containers, but gallon milk jugs are among the best. These giant water jugs are even better. You cut around the jug, about 3/4 of the way up, stopping at the back to make a hinged lid that can be lifted. Cut off the spigot and leave it open, so water can get in and evaporate out. I also made drain holes across the bottom, and a few venting holes on the side. Some wintersowing sites suggest you drill the holes or punch them out with an awl, but I found it to be easier--less likely to result in bloodletting for a clumsy person--to heat up a metal skewer in the flame of the gas stove, and use the hot metal point to poke holes.
Then you fill the bottom with moistened potting soil or seed starter mix (I used a combination of both, so it was light for germination but would nourish the seedlings as they grew,) and sow it with seeds. Most wintersowing sites suggest you close the halves of the jug with duct tape, but I found an idea I like better. You just poke a hole in the upper lid and one in the lower, and tie the them together with a twist tie, or I used garden twine. This keeps it closed in the wind, but allows a little venting on the sides. It also seems like it would be easier to check the seedlings this way. I like how the height of these containers will allow even tall seedlings to stay protected until it's time to plant them out.
Then you set the jug outside, and wait until spring. I put this jug next to a container of asters I started last week. If it's been very dry, you water the jugs through the top. This method is supposed to work especially well for plants that need a period of cold stratification, like some flowers that are perennial in Colorado. They can freeze and thaw in the soil to stratify, but there is heat and sun inside the jug and the seeds stay safe from birds until they have a chance to germinate and grow. They also don't travel around, like seeds in the open do when snow melts.
These are some of the flowers I'm planning to wintersow. I'm intrigued by this idea, of using the sun and snowmelt to grow some of your seedlings without the resources of lights and water indoors. I hope that at least some of them work. It would be a lot better than paying for flats of nursery flowers in the spring.
