Winter Growing & Season Extension

Video: Winter Sowing & Milk-Jug Greenhouses | With Niki Jabbour & Johnny's

Hi, I'm Niki Jabbour. And today I want to talk about winter sowing.

What is Winter Sowing?

Winter sowing is a seed starting technique where the seeds of certain flowers, vegetables and herbs are planted outdoors in containers in late fall or winter. The cold weather stratifies the seeds and prompts germination when the time is right.

The Benefits of Winter Sowing

There are many benefits to winter sowing. First, it's an easy way to start many types of plants without going to the trouble of indoor seed starting.

It's also budget friendly as there's no need to invest in grow lights or pots and seeding trays. Most gardeners use recycled items like milk and water jugs, soda bottles or salad containers for winter sowing. These containers act as miniature greenhouses and should be deep enough to hold at least 3 to 4 inches of potting mix and tall enough to accommodate the growing seedlings. Other supplies you'll need for winter sowing include seed-starting mix or an all purpose potting soil, labels and a waterproof marker, duct tape and scissors. And of course, something sharp to poke holes in the bottoms of the containers.

When to Sow Seeds for Winter Sowing

As you may have guessed from the name, winter sowing is done during the cold months of winter. I usually sow seeds in January once the holidays have passed and my seed orders have arrived. If you plant too early in autumn, the seeds may sprout and not survive the winter. On the other hand, if you wait too late in winter, there may not be enough cold weather left to stratify the seeds. Most types of seeds need several months of cold, moist conditions to prompt germination.

Prepping Your Winter Sowing Containers

When you're ready to sow, start by preparing the containers.

  • Add Drainage Holes & Ventilation Holes

    I poked drainage holes in the bottoms of my containers using a drill, pointed screwdriver, or old steak knife. Be very careful and wear safety glasses for this step. I also add ventilation holes to the tops of the containers to allow warm air to vent on mild days.

  • Cut A Lid Into The Container

    If planting in milk jugs or soda bottles, the next step is to make a cut about four inches up from the bottom of the container. Using scissors, cut almost the entire way around the container, leaving a small hinge at the back—this allows the greenhouse to open and close.

  • Add Potting Soil & Plant Your Seeds

    Add several inches of moist potting mix to the container and plant the seeds at the recommended depth. Check the seed packet for specific seeding depth information. Record the plant type, variety, and sowing date on a tag and tuck it inside. Using duct tape, close and seal the jug or container. I also write down the plant type and date on the outside surface with a waterproof marker.

Where to Place Your Winter Sowing Mini-Greenhouses

Once all the seeds are planted, place the containers outdoors in a sunny but sheltered spot like a deck, patio, alongside a garden shed or next to a raised bed. As the weeks and months pass, the containers will likely be covered with snow. That's fine as you want the winter weather to work its magic. Remove the caps every couple of weeks to make sure the potting mix is still moist. If it seems dry, sprinkle in some water.

As winter turns to spring, the seeds will germinate and begin to grow. At this point, keep a close eye on soil moisture, watering when necessary. And when the outdoor conditions are right, transplant the seedlings into the garden.

Vegetable, Flower, and Herb Crops for Winter Sowing

Winter sowing is a technique that's very effective in growing a wide range of plants like lupines, black-eyed Susans, coneflowers and milkweed. I also use it to start pansies, snapdragons, marigolds and calendula. And there are many edibles you can winter sow, including cabbage, kale, broccoli, onions, leeks, parsley, cilantro, lettuce and bok choy.

Happy growing!

Watch Niki's tutorial on building a DIY Cold Frame…