Winter sowing trick to extend the season for higher latitude gardening

Found this interesting article about how to leverage plastic containers as micro-greenhouses for winter sowing in high latitude climates with short summers: https://www.cbc.ca/news/canada/calgary/how-to-garden-in-the-winter-no-gr...

The gist, in case the article disappears, is as follows (quoted from the article):

First, you'll need a clean and empty plastic milk jug, Smyth says. It can be a two-litre or four-litre container, or any clear takeout container with a lid.

If using milk jugs, toss out the cap so the plants can get moisture from the snow. If using a takeout container or clamshell with a lid, cut some slits in it so water can get in. "They do need venting," Smyth said.

Punch six to eight holes in the bottom of the container for drainage. Then, make a cut about four inches from the bottom, leaving an inch near the handle area intact, acting as a hinge.

Fill the jug with potting soil to a depth of 3½ inches and pat down into a smooth seeding surface.

After that, you can plant your seeds, ensuring you follow the directions on the package. Plants like spinach, kale and lettuce work well in cooler weather, she said. "Space them out a bit, [..] don't just dump the whole package in."

Then, tape up the jug with duct tape and label it with the seed planted inside.

The next step might seem counterintuitive: place them outdoors. Smyth says the jugs can be placed in a snowbank and they should be out of the wind and out of direct sunlight, though it's OK for them to get some sun.

"Over at the horticulture society in the gardens there, we tucked them in among the shrubs and along the fence line where the sun stays on them [in the morning] and they germinate," she said, adding they pick the spot so the snow will gather on them and create insulation.