Get your hands dirty this winter by starting seeds outdoors using a practice called winter sowing. This method forgoes supplemental lighting and pricey seed-starting kits and lets nature’s rhythms coax seeds to sprout. Winter sowing is simple and yields sturdy seedlings that are ready to grow. If you have avoided starting seeds because you lack space or sunny windows, check out winter sowing.
To get started with winter sowing, you’ll need supplies you probably have around the house. Plastic containers, like milk jugs, 2-liter bottles or clear-lidded clamshell-type containers serve as a mini-greenhouse for the seeds. Use a box cutter or pen knife to cut around the middle of the container. Leave roughly a one-half inch section uncut to act as a hinge. What you’re doing is creating a hinged container that opens. Clamshell containers don’t require cutting.
Punch drainage holes in the bottom of the container. Use a lighter to heat the tip of the screwdriver to make punching through plastic easier. The container forms a mini-greenhouse for your seeds. Cut slits in the lid of the container to provide ventilation and prevent heat build-up. If your container has a lid (milk jug, 2-liter bottle), remove it.
Fill the container with 2 to 3 inches of soil. Winter sowing works best with a soil a mix that’s light and drains well. Bagged commercial peat moss and perlite mixes work great. Avoid mixes that feature water retention agents or moisture control properties. Wet soil thoroughly, place seeds on the surface, and add additional soil as needed to cover seeds. Pat the soil lightly to ensure good seed to soil contact, and close your container. Use a piece of duct tape to hold the container closed. Be sure to label containers with planting date and seed.
Set your planted containers outdoors in a spot that’s protected from winds, but receives sunlight, snow and rain. You might want to place your containers into a greenhouse flat or plastic tub to ensure your little greenhouses stay upright. Make sure the tray has drainage holes—if not, create them.
Winter sowing relies on cycles of freezing and thawing to loosen seed coats and prepare seeds to germinate. When spring first arrives with sunny days but still freezing nights, you’ll start spotting seedlings. At this point, on a day when temperatures are above freezing, open containers and check soil dryness. Water if needed, using a gentle spray. Replace lids.
As spring settles in and air steadily warms, open containers during the day for a few hours to start hardening off seedlings. Continue to tape containers closed at night to protect seedlings from chilly air. Eventually as nights warm, you can leave container lids off permanently. Plant seedlings into the garden or containers on a cloudy day to reduce transplant shock.
Winter sowing works with perennials, hardy annuals, vegetables, herbs and tender annuals. You just have to get the timing right. Sow seeds for plants that are hardy in your zone—including hardy annuals and vegetables—anytime during winter. Tender plants—including annuals and vegetables—should be sown closer to spring (March or April in Zone 5). Heat-loving vegetables, like tomatoes, should be planted a month later.