How to Winter Sowing Seeds in Plastic Milk Jugs
What Is Winter Sowing?
Winter sowing is a super simple gardening technique that allows seeds to germinate outdoors during the cold winter months. This means less time starting seeds and more time to relax!
Winter sowing uses natural cold stratification, which is when seeds need cold weather exposure before germinating (source). This exposure to a cycle of freezing and thawing can help break a seed’s dormancy and mimics natural seasonal conditions.
One of the best parts about winter sowing is how beginner-friendly it is. Plus, you can grow a variety of plants—from hardy vegetables to beautiful perennials—using this effective and easy method. You will still need to do some Spring planting for warmer plants like Peppers and Tomatoes, but Winter sowing gives you a huge head start on your garden!
For Spring planting, take a look at our top choices for Herbs, Flowers, or Vegetables.
Benefits of winter sowing:
- Cost-effective and low maintenance: winter sowing is a great way to get a jumpstart on Spring gardening without the need for indoor grow lights or heating mats
- Hardiness: Seeds adapt better to outdoor conditions when they are not transplanted from indoor conditions
- Space: With everything cozied up outside, this reduces any indoor clutter and energy consumption you might have used from lights and mats
- Time: One good afternoon of hard work is all you need, winter sowing is not going to take weeks and no constant monitoring is needed
- Recycling: Using old milk jugs instead of throwing away repurposes your plastic waste, making winter sowing eco-friendly
Why Milk Jugs Are Perfect for Winter Sowing
Milk jugs are the best containers for winter sowing because they’re readily available, inexpensive, and it’s an easy way to repurpose. We ask our family and friends to save theirs throughout the Fall so we have plenty to work with (and we promise to share the bounty!).
When cut and prepped correctly, milk jugs act as miniature greenhouses. They trap in warmth and moisture while still protecting seeds from any extreme weather. Their translucent plastic material lets enough sunlight in without scorching and allows enough rain without flooding, which provides the perfect environment for seed germination.
Another advantage of using milk jugs is their portability. You can move them around your yard to optimize sunlight exposure or protect them from extreme weather. You can alternatively use clear plastic bins or totes if that is what you have around.
Supplies You’ll Need for Winter Seed Sowing
To get started with winter sowing in milk jugs, you’ll need the following supplies:
- Milk Jugs: Clean, empty plastic jugs without the caps
- Soil: Use a lightweight, well-draining mix to promote healthy root growth
- Scissors or Knife: For cutting the jugs in half to get soil and seed inside
- Drill: To making drainage holes in the bottom of the milk jug
- Duct Tape: For sealing jugs after planting and watering
- Seeds: Choose frost-hardy or varieties that need cold temperatures
- Markers or Labels: Use permanent marker or waterproof markers or vinyl printed labels (I prefer these)
- Watering Can: You will want to give an initial good watering, and then only occasionally if you see the soil is drying out
Best Seeds for Winter Sowing
Not all seeds will work for winter sowing, but many thrive under these conditions. Hardy seeds that naturally require cold stratification to break dormancy are the best choice.
You can check seed packets for phrases like “cold-hardy,” “frost-tolerant,” or “requires stratification” to find the best candidates. Here are some great seed variety (not an exhaustive list):
Hardy Perennials
- Coneflowers
- Black-eyed Susans
- Lupines
- Columbines
Cold-Tolerant Vegetables
- Kale
- Spinach
- Lettuce
- Broccoli
- Brussels Sprouts
- Cabbage
Flowers
- Milkweed
- Coreopsis
- Poppies
- Yarrow
- Snapdragons
- Calendula
Herb Seeds
- Chamomile
- Beebalm
- Butterfly weed
- St. John’s wort
- Comfrey
Step-by-Step Instructions to Winter Sowing in Milk Jugs
Step 1: Preparing Your Milk Jugs
- Start by cleaning your milk jugs thoroughly to remove any residue and to prevent mold. Let them dry completely before using. Remove lids to create ventilation holes.
- Drill or poke several drainage holes in the bottom of the jug to prevent water from drowning or causing root rot to your seeds.
- Using scissors or a utility knife, cut the jug horizontally about two-thirds of the way up, leaving a small hinge uncut near the handle to keep the two pieces connected.
Step 2: Adding Soil and Seeds
- Fill the bottom part of the jug with about 3-4 inches of soil. Don’t just use old garden dirt, try to find a regular potting mix or potting soil mixture to use.
- Sow seeds in the jugs according to the depth and spacing recommendations on the packet, typically around 1/4 to 1/2 inch deep. Some seeds you will just need to sprinkle on top of the soil.
- Lightly water to make sure the soil is moist but don’t flood it.
Step 3: Sealing and Labeling
- I like to put printed vinyl labels I make on my Cricut machine on the inside of the jugs. This seems to prevent washing away of ink. You can also put a labeled plant marker stick inside.
- Fold the top of the jug back into place and secure it with duct tape around the seam. Be sure to leave the caps off the jugs to allow for proper air circulation and for moisture to get in.
- You can also use a permanent or weatherproof marker to label your jugs on the outside. Just don’t forget to label because as hard as we try try we won’t remember!
Step 4: Place Jugs Outdoors
Place your jugs in a sunny, sheltered spot where they’ll get exposure to rain and snow, but can avoid strong winds or shade. You want the sun to help warm them during the day.
Step 5: Germination
As temperatures increase in late winter or early spring, the seeds will start to germinate naturally. There is no need to do anything else to assist this. Watch for tiny green sprouts, then do a happy dance!
Caring for Your Milk Jug Winter Mini Greenhouse
Once your milk jugs are prepared and in place, you just need to make sure they have a couple of things.
- Watering: You will only need to monitor your seed occasionally (more so if there’s been a long dry period). Every few days take a look to ensure the soil remains moist. If it is dry, water a bit through the lid opening. You want the soil to be moist but not soggy.
- Sunlight: Place the jugs where they can receive 6-8 hours of sunlight daily. Avoid areas prone to heavy winds or flooding. It’s okay if you need to move them from their first location.
- Seedlings: Once your seedlings have sprouted you may need to thin them a bit to prevent overcrowding and ensure healthy plants.
Transplanting Seedlings to the Garden
When your seedlings have grown strong and the danger of frost is gone, it’s time to transplant your plant babies into your garden. Follow these steps for a successful transition:
- Temperature: Check your local last frost date. Transplant once your garden soil has warmed and the weather is stable. Most winter-sown seedlings will be ready to plant late spring. Some you may be able to transplant earlier, just check the seed packet information.
- Hardening Off: Normally indoor sown seeds have to be hardened off over a few days time, but winter-sown seedlings are naturally more hardy. That being said, it’s never a bad idea to gradually get them used to life outside the jug. If the risk of frost has passed you can start giving your seedlings more fresh air by opening the top of the jugs during the day and giving them some partial sunlight a few days before transplanting.
- Prepping Your Garden: Amend the soil in your garden bed, remove weeds or debris.
- Transplanting: Carefully remove the seedlings from your jugs and plant them at the same depth they were growing in the jugs. I like to use a spoon to take them out to ensure some soil stays on the roots. Water plants thoroughly after transplanting. Your seedlings will quickly adapt to their new spot and begin to grow even bigger!
- Save the jugs: Don’t throw your jugs away, keep them for next year. Just give them a rinse, dry them out and store for next season.
Common Mistakes and How to Avoid Them
Even though winter sowing is beginner-friendly, there are a few common mistakes to watch for:
- Overwatering or Underwatering: Milk jugs need proper drainage to avoid root rot, but they can also dry out quickly during sunny winter days. Check the soil moisture periodically and water as needed.
- Wrong Seeds: I have made this mistake countless times, mostly for experiments sake, but don’t get discouraged. Seeds that aren’t frost-hardy or don’t require cold stratification may fail to germinate (although you may get lucky and sometimes it just depends on the weather!). Try to stick to seeds that are usually grown in early spring or the fall.
- Labeling: It’s easy to forget what you planted, especially if you’re sowing multiple types of seeds. Use waterproof markers, vinyl printed labels, or planter sticks to clearly identify each plant.
- Drainage Holes: The biggest mistake I see when winter sowing is that people forget to add holes to the bottom of their containers. Double-check that you’ve added enough holes in the bottom (about 4-8).
Whether you’re a seasoned gardener or a beginner, winter sowing in milk jugs is a simple way to start your growing season early. This method requires minimal effort and no really fancy equipment and you’ll be able to grow a variety of flowers, vegetables, and herbs with ease. So, grab those milk jugs, gather your supplies, and start winter sowing today!
How to Winter Sow Seeds in Plastic Milk Jugs
Start seeds easily with winter sowing in milk jugs. This simple sowing method will give you strong, healthy seedlings for spring planting.
Materials
- Milk Jugs: Clean, empty plastic jugs without the caps
- Soil: Use a lightweight, well-draining mix to promote healthy root growth
- Duct Tape: For sealing jugs after planting and watering
- Seeds: Choose frost-hardy or varieties that need cold temperatures
Tools
- Scissors or Knife: For cutting the jugs in half to get soil and seed inside
- Drill: To making drainage holes in the bottom of the milk jug
- Markers or Labels: Use permanent marker or waterproof markers or vinyl printed labels (I prefer these)
- Watering Can: You will want to give an initial good watering, and then only occasionally if you see the soil is drying out
Instructions
Step 1: Preparing Your Milk Jugs
- Start by cleaning your milk jugs thoroughly to remove any residue and to prevent mold. Let them dry completely before using. Remove lids to create ventilation holes.
- Drill or poke several drainage holes in the bottom of the jug to prevent water from drowning or causing root rot to your seeds.
- Using scissors or a utility knife, cut the jug horizontally about two-thirds of the way up, leaving a small hinge uncut near the handle to keep the two pieces connected.
Step 2: Adding Soil and Seeds
- Fill the bottom part of the jug with about 3-4 inches of soil. Don't just use old garden dirt, try to find a regular potting mix or potting soil mixture to use.
- Sow seeds in the jugs according to the depth and spacing recommendations on the packet, typically around 1/4 to 1/2 inch deep. Some seeds you will just need to sprinkle on top of the soil.
- Lightly water to make sure the soil is moist but don't flood it.
Step 3: Sealing and Labeling
- I like to put printed vinyl labels I make on my Cricut machine on the inside of the jugs. This seems to prevent washing away of ink. You can also put a labeled plant marker stick inside.
- Fold the top of the jug back into place and secure it with duct tape around the seam. Be sure to leave the caps off the jugs to allow for proper air circulation and for moisture to get in.
- You can also use a permanent or weatherproof marker to label your jugs on the outside. Just don't forget to label because as hard as we try try we won't remember!
Step 4: Place Jugs Outdoors
Place your jugs in a sunny, sheltered spot where they’ll get exposure to rain and snow, but can avoid strong winds or shade. You want the sun to help warm them during the day.
Step 5: Germination
As temperatures increase in late winter or early spring, the seeds will start to germinate naturally. There is no need to do anything else to assist
Notes
- Overwatering or Underwatering: Milk jugs need proper drainage to avoid root rot, but they can also dry out quickly during sunny winter days. Check the soil moisture periodically and water as needed.
- Wrong Seeds: I have made this mistake countless times, mostly for experiments sake, but don't get discouraged. Seeds that aren’t frost-hardy or don’t require cold stratification may fail to germinate (although you may get lucky and sometimes it just depends on the weather!). Try to stick to seeds that are usually grown in early spring or the fall.
- Labeling: It’s easy to forget what you planted, especially if you’re sowing multiple types of seeds. Use waterproof markers, vinyl printed labels, or planter sticks to clearly identify each plant.
- Drainage Holes: The biggest mistake I see when winter sowing is that people forget to add holes to the bottom of their containers. Double-check that you’ve added enough holes in the bottom (about 4-8).
FAQS
The best time to start winter sowing is between December and February, depending on your climate. This gives seeds enough time to germinate before spring.
An initial watering of the soil is required. After that, rain and snow usually provide enough moisture, but you should check occasionally and water lightly if the soil is drying out.
Cold-hardy seeds are best (cool weather plants that thrive in spring and fall). Avoid any summer plants like tomatoes, peppers, and cucumbers, as they need warm temperatures in order to germinate.
Once the soil warms up in early spring, you can remove the seedlings from the jug gently and plant them directly in your garden or containers. They have already been acclimated to the weather.
Yes! Winter sowing mimics natural germination, and cold-hardy seeds are designed to withstand freezing temperatures, and often require a cold period.
This is so great! I’ve heard about winter sowing and wondered what it means and what the fuzz is all about. Now I know! And I love the idea! I don’t have a whole lot of jugs, but I’ll try to find the ones I saved and start some cabbages! Thanks so much for sharing. This is super helpful!