By Sara Toler
Winter sowing is the practice of starting seeds outdoors in mini-greenhouses made from recycled containers (typically milk jugs, tupperware, plastic zip lock bags, rotisserie chicken containers) during the cold winter months. Seeds are planted in a damp potting mix, placed outside, and left to sprout naturally as the weather warms. This truly is a quick and easy way to get a headstart on your gardening.
This method works well in Michigan because:
- Seeds stay dormant during freezing periods.
- Snow and rain provide moisture.
- Fluctuating temperatures trigger natural germination.
- Seedlings grow tough, weather-ready, and acclimated.
Which Seeds Work Best For Winter Sowing in Michigan?
Not all seeds are ideal for winter sowing, but many thrive with this approach—especially those that require or tolerate cold stratification (the seed must experience winter before they will germinate). If your seeds require cold stratification, it is usually listed on the back of the seed packet.
Best options include:
- Perennials:Â coneflowers, black-eyed Susans, milkweed, lavender, yarrow
- Cold-hardy vegetables:Â kale, cabbage, broccoli, brussel sprouts
- Greens:Â spinach, lettuce, Swiss chard
- Cold-tolerant annuals:Â snapdragons, sweet peas, pansies
Avoid: heat-loving crops like tomatoes, peppers, and basil until later in the season (late March/April).
Step By Step Guide To Winter Sow With Milk Jugs:
1. Prepare the Milk Jug
- Rinse the jug thoroughly (water jugs work best).
- Cut around the jug horizontally, leaving about 2 inches connected beneath the handle so it can open.
- Remove the cap (this allows for ventilation and precipitation).
2. Add Drainage Holes
Use a knife or screwdriver to poke several holes:
- In the bottom for drainage
- A few around the sides for airflow
Drainage is needed to prevent waterlogging when thaws happen.
3. Fill with Potting Mix
Add 3–4 inches of pre-moistened potting mix ( not so moist that the water is dripping from the soil).
4. Plant the Seeds
- Scatter seeds according to packet instructions.
- For tiny seeds, gently press them into the soil without covering.
- For larger seeds, cover lightly.
Label the container clearly with a permanent marker.
5. Close and Seal
- Fold the jug closed and secure it with duct tape.
- Leave the top hole (where the cap was) open for air and moisture.
6. Place Outdoors
Set the jugs outside in an area exposed to:
- Full sun
- Snow
- Rain
Do not protect them from the weather. Exposure to natural conditions is part of what makes winter sowing successful.
7. Let Nature Do the Work
During winter, nothing appears to happen but inside the jug:
- seeds remain cold-stratified
- soil stays naturally moist
- light enters and warms the mini-greenhouse on sunny days
- by late March or early April you will start to see little green sprouts appear
Transplanting Seedlings
When daytime temperatures consistently reach the upper 50s–60s°F, seedlings will be ready to move out.
Steps:
- Gradually open the jugs fully for a few days to harden off the plants.Â
- Gently remove the seedlings from the container.
- Transplant into garden beds or larger pots when the soil is workable.
Winter-sown seedlings are typically sturdier and more cold-tolerant than indoor-grown ones, making transplanting easier.
Winter sowing in milk jugs is one of the most efficient and rewarding ways to start seeds in Michigan’s climate. Instead of battling for indoor space or relying on grow lights, you can let nature take the lead and end up with strong, resilient plants.
It’s beginner-friendly, sustainable, and surprisingly fun—making it a perfect method for gardeners of all experience levels.