You can grow summer plants outside in the Maine winter

There’s one way to grow plants right now that actually works better the colder it gets.

It’s simple to make mini “greenhouses” with household materials like clear plastic baggies, food containers or gallon jugs where seeds can grow through the winter.

Called winter sowing, it’s a way to start plants in the cold months that will prepare them to thrive in spring.

You can gather the materials you need around your kitchen without added expense, and the seedlings it produces are cold-hardy, ready to grow outside and can be started without lights, heat trays or other expensive equipment.

Some gardeners have also found that the method gives them a higher germination rate for their seeds and that the seedlings are less likely to be leggy. To get the timing right, many use the solstice as a starting date for winter sowing. This year, that’s Saturday, Dec. 21.

The method was developed by New York gardener Trudi Davidoff almost 25 years ago. There are now Facebook groups dedicated to education about winter sowing and numerous webinars with detailed guides.

The process varies a bit based on who you ask and what plants you’re trying. But, basically, you’ll start by poking drainage holes in the bottom of your milk jug or plastic container and air holes in the top half. One way to do this is with a heated screwdriver to burn through the plastic. Cut gallon containers mostly in half, leaving a small part connected like a hinge.

Fill it with 3 or 4 inches of soil, moisten it and sow your seeds. Tape the tops of the containers down. Leave them outside and wait until the seedlings have a few leaves and are ready to transplant.

You can do a similar process with slightly opened plastic baggies held up by dowel rods as well, and there are online gardening pages dedicated just to that method too.

Winter sowing is best suited to hardier vegetables; it can work with most greens, beets, onions, broccoli, cauliflower, Brussels sprouts, peppers and squash, perennial plants, herbs, shrubs and trees.

This method can work particularly well for wildflower or other native plant seeds that need stratification, or a period of cold weather, before they’re ready to germinate. Research how long the types you’re interested in will take to be ready for planting.

Varieties with longer germination periods or more cold-hardiness should be started soon. Seeds that mature faster can be started in late winter or early spring depending on your growing zone.