If you love gardening but hate waiting until spring to start growing, winter seed sowing is for you! This easy and low-cost method allows gardeners in Zones 5 and 6 to start hardy seedlings outdoors during winter using recycled milk jugs. When done correctly, this technique creates a mini-greenhouse effect that protects seeds and helps them sprout at the perfect time. Here’s how to do it!
Why Sow Seeds in Winter?
• Mimics Nature – Many seeds require a period of cold stratification to germinate. Winter sowing provides this naturally.
• Stronger Plants – Because the seedlings emerge outdoors in their natural environment, they are hardier and less prone to transplant shock.
• Saves Space Indoors – No need to clutter your house with seed trays and grow lights!
• Water Efficient – The enclosed jugs hold moisture, reducing the need for frequent watering.
What You’ll Need
• Clean, empty milk jugs (or similar clear plastic containers)
• Bleach to sterilize the jugs
• Utility knife or scissors
• Duct tape
• Permanent marker
• As potting soil use Deep Roots microbe-rich compost and worm castings mixed 1:1 ratio
• Seeds suitable for winter sowing
• Water
Step-by-Step Guide
1. Sterilize the jugs. Fill a large container or your bathtub with water and 10% bleach. Soak the jugs for about 20 minutes. Then soak in clean water for 20 minutes to remove the bleach.
2. Prepare the Jugs: Cut the milk jug almost in half, leaving a small hinge near the handle. Poke drainage holes in the bottom.
3. Fill with Soil: Add 3-4 inches of moist potting soil or seed-starting mix.
4. Plant the Seeds: Sow seeds according to the recommended depth on the seed packet.
5. Close & Label: Tape the jug shut and label it with the seed type and date.
6. Set Outside: Place the jugs in a sunny, sheltered location. Snow and rain will help keep them hydrated.
7. Monitor & Ventilate: As temperatures warm in early spring, check for condensation inside the jugs. If it gets too hot, open the top during the day.
8. Transplant When Ready: Once seedlings have several sets of true leaves and the risk of frost has passed, transplant them into your garden beds.
Best Seeds for Winter Sowing
Many cold-hardy flowers and vegetables thrive with this method, including:
• Flowers: Milkweed, poppies, echinacea, black-eyed Susan, columbine
• Vegetables: Kale, lettuce, spinach, broccoli, onions, parsley
• Herbs: Thyme, sage, chives, oregano
Tips for Success
• Use translucent containers—clear plastic may allow too much light and heat.
• Don’t overwater before sealing the jugs—moist but not soggy is ideal.
• Keep jugs in full sun to ensure proper warmth as temperatures fluctuate.
• Be patient! Some seeds take longer to sprout than others, especially native plants.
Why This Works So Well in Zones 5 & 6
These zones experience cold winters but still have enough late-winter sun to warm up the mini-greenhouses. Seeds naturally break dormancy when conditions are right, leading to healthier plants that are better adapted to outdoor conditions.
Winter sowing using milk jugs is a great way to get a head start on your garden while making the most of the cold months. Give it a try, and come spring, you’ll have strong, thriving seedlings ready to transplant!
Best Seeds for Winter Sowing in Milk Jugs
Winter sowing is ideal for cold-hardy plants and those that require cold stratification. While summer vegetables like tomatoes, peppers, cucumbers, and squash can be winter-sown, they are not the best candidates because they prefer warm soil and sprout best indoors under controlled temperatures. However, you can still give them a try using this method if you plant them later in winter.
Best Seeds to Winter Sow by Category
Cold-Hardy Vegetables & Herbs
Great for Winter Sowing - these plants can be started 10-12 weeks before the last frost
• Kale (10-12 weeks before last frost)
• Spinach (10-12 weeks before last frost)
• Lettuce (8-10 weeks before last frost)
• Swiss Chard (8-10 weeks before last frost)
• Broccoli (8-10 weeks before last frost)
• Cauliflower (8-10 weeks before last frost)
• Brussels Sprouts (10-12 weeks before last frost)
• Cabbage (8-10 weeks before last frost)
• Collard Greens (10-12 weeks before last frost)
• Onions & Leeks (10-12 weeks before last frost)
• Carrots (8-10 weeks before last frost)
• Beets (8-10 weeks before last frost)
• Radishes (8-10 weeks before last frost)
• Turnips (8-10 weeks before last frost)
• Parsley (10-12 weeks before last frost)
• Chives (10-12 weeks before last frost)
Perennial & Hardy Annual Flowers
Excellent for Winter Sowing - many flowers need cold stratification, making them perfect for winter sowing.
• Milkweed (12+ weeks before last frost)
• Echinacea (Coneflower) (10-12 weeks before last frost)
• Black-eyed Susan (Rudbeckia) (10-12 weeks before last frost)
• Poppies (10-12 weeks before last frost)
• Lupine (10-12 weeks before last frost)
• Columbine (10-12 weeks before last frost)
• Snapdragons (8-10 weeks before last frost)
• Delphinium (10-12 weeks before last frost)
• Foxglove (10-12 weeks before last frost)
• Hollyhocks (10-12 weeks before last frost)
• Bachelor’s Button (8-10 weeks before last frost)
Summer Vegetables
Summer vegetables are NOT the best candidates for winter sowing because they need warm soil to germinate. If planted too early, they may rot instead of sprouting. You can winter sow them later in the season - but you must wait until late winter/early spring (6-8 weeks before last frost) to avoid premature sprouting in cold weather.
• Tomatoes (6-8 weeks before last frost)
• Peppers (6-8 weeks before last frost)
• Eggplants (6-8 weeks before last frost)
• Basil (6-8 weeks before last frost)
• Cilantro (6-8 weeks before last frost)
• Cucumbers (4-6 weeks before last frost)
• Squash (Zucchini, Pumpkin, Winter Squash) (4-6 weeks before last frost)
• Melons (4-6 weeks before last frost)
Happy Gardening!
By following the Deep Roots Project’s transformational gardening methods through the seasons, you will create a thriving, nutrient-rich garden that supports both your plants and the soil. See the full list of our Grow Your Own Food blog posts. Each post is assigned ”tags” which are under the post title.
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