Winter Sowing: The Easiest Way to Start Seeds in Cold Weather
Winter sowing involves sowing the seeds outdoors in miniature greenhouses during the winter, allowing them to germinate naturally in spring.
Starting seeds indoors can feel like a whole production between grow lights, watering, and remembering to harden things off. I used to think it was the only way until I discovered winter sowing. I stopped trying to control every step, and the plants honestly did better.
Winter sowing is simply starting seeds outside, in covered containers, and letting winter and spring do their thing. It’s perfect for gardeners in northern climates like Maine and works really well with hardy vegetables, herbs, and flowers.
Here’s how I do it and what I’ve learned along the way.
What is Winter Sowing?
Winter sowing is an easy way to start seeds outside using recycled plastic containers as mini-greenhouses. The seeds go through real winter conditions, which helps them break dormancy and grow stronger once spring arrives.
One thing I really like about winter sowing is since the seedlings germinate in outdoor conditions, they’re already adapted to temperature shifts and sunlight, so no back-and-forth every day trying to harden things off.
My biggest seed-starting struggles were forgetting to water seedlings or hardening them off too late. With winter sowing, nature takes care of those steps for me!
How to Sow Seeds in Winter
Winter sowing is simple, but there are a few basics you’ll need to get started. The container just needs to protect the seeds while letting in light and moisture. Here’s what I use and how I get everything ready.
Choose Your Containers
You’ll need a clear or translucent plastic container that holds at least 3-4 inches of soil and allows light to pass through. These are the containers I’ve had the best luck with:
- Milk jugs (my personal favorite)
- 2-liter soda bottles
- Large plastic take-out containers
- Big pretzel or snack tubs
I like milk jugs because they’re sturdy, easy to line up, and the caps come in handy later.
Preparing the Containers
Once you’ve chosen your containers, it’s time to get them ready for winter sowing. Before anything else, make sure water has somewhere to go.
Create Drainage Holes
Use a drill or knife to poke 3-4 holes in the bottom and sides (about ¼ to ½ inch up). This prevents water from pooling and causing rot. Freeze the container with water inside before drilling. It keeps the plastic from collapsing under pressure.
Cut a Hinged Lid
Using a sharp knife or utility blade, carefully cut around the container, leaving about an inch uncut to create a hinge. This hinge will allow you to easily open the container for planting, watering, and checking on your seedlings as they grow. Be sure to cut high enough to allow at least 3-4 inches of soil in the bottom portion while leaving enough room for seedlings to sprout and develop inside their mini greenhouse.
If using a thicker plastic container, score the cut line first to make slicing easier and ensure a clean, controlled cut.
Planting in Your Milk Jug
Now that your mini greenhouse is ready, planting is easy. Here’s how I do it.
- Fill the container with moist potting soil about 3-4 inches deep.
- Sprinkle seeds according to the packet instructions for depth and spacing. (I tend to overseed a little, and it still works out fine.)
- Duct tape the lid closed and remove the cap (or poke holes in the top of the container) to allow rain and snow to enter.
- Label the container with a waterproof marker or plant tag to identify the seedlings in spring.
Placing Your Mini Greenhouses
Once your containers are ready, it’s time to put them outside. This is where I put mine:
- Somewhere visible but protected from foot traffic. If you have kids who love building snowmen, you might want to mark the area!
- In an open area where they’ll get direct rain and sunlight. Avoid spots under eaves or trees.
- In a sunny location to warm up naturally in spring so I don’t have to mess with them later.
When to Start Your Seeds in Maine (5b)
This is the rough schedule that works well for me in Zone 5, but you can adjust based on your local last frost date.
January
- Perennial Flowers
- Hardy Annual Flowers
- Brussels Sprouts
February
- Spinach
- Kale
- Peas
- Broccoli
- Thyme
- Sage
- Oregano
- Cilantro
March
- Lettuce
- Carrots
- Basil
- Parsley
- Bok Choy
- Beets
April
- Tomatoes
- Onions
- Peppers
Need a different planting schedule? Find winter sowing dates for your growing zone here.
If your containers didn’t sprout the way you expected, or seedlings stalled once they did, you might be dealing with one of these common winter sowing mistakes. I break down the small setup and timing issues that can derail your results so you can fix them before next season.
Recommended Reading
If winter growing grabs you, these are good ones to have on the shelf.
Winter Gardening for Beginners by Lindsey Pylarinos
If you’re brand new to winter gardening, this is an easy place to start. It walks through cold-weather growing in a way that’s approachable and not overwhelming, especially if you’re still figuring out what’s realistic for your space and climate.
The Winter Harvest Handbook by Eliot Coleman
This is a classic for a reason. Eliot Coleman focuses on practical, low-tech ways to grow food through the winter using season extension tools like cold frames and hoop houses. It pairs really well with winter sowing if you want to keep pushing your growing season.
Four-Season Harvest by Eliot Coleman
This book goes deeper into planning, timing, and storage for year-round food production. If you like understanding the why behind growing methods and want to fine-tune your approach, this one’s worth the read.
The Year-Round Vegetable Gardener by Niki Jabbour
One of my favorites for cold-climate gardening. Niki Jabbour shares realistic planting schedules, crop ideas, and season-extension strategies that work for backyard gardens, even in shorter growing seasons.
Still Wondering How Winter Sowing Works?
If you’re new to winter sowing, this is the stuff you’re probably wondering about.
Have a specific plant in mind or wondering if winter sowing will work where you live? This winter sowing guide goes deeper into timing by growing zone and answers a lot of the questions that tend to come up once you’re ready to try it.
Pin this for later if you want strong seedlings without grow lights or hardening off.
For me, winter sowing has been the easiest way to start seeds. There’s no grow light setup, no transplant shock, and no tedious hardening-off process. I set them up, put them outside, and let the weather do its thing. There’s no need to obsess over frost dates with this method.
The biggest learning curve with winter sowing is timing, especially across different growing zones. Knowing your gardening zone and frost dates will help you determine the best planting schedule, while understanding how to read a seed packet makes sure you’re choosing the right seeds for your climate.
Have you tried winter sowing before? What plants have worked best for you? Drop your experience or questions in the comments below!
I would love to use this article as a link. We are homeschoolers, and are trying this method for our gardening unit. Pretty please, may we link?
Absolutely! Thank you so much Jodie 🙂
Love this idea! Question, do you keep the cap on or off?
Cap off so the rain can water them 🙂
thanks! I have a ton of these jugs,so I’ll be busy making these this week!
Great idea, thanks! I do have one question. Do you lift the lids on warm days, or leave them taped shut until you’re ready to transplant?
I leave them taped up until I’m ready to put them in the ground, but I do move them in the shade if they seem to be getting a bit toasty.
Thank you!
I used my hot glue gun without any glue to melt the holes in the milk jugs. Worked like a charm!
That’s a great way to get holes in your carton without hurting yourself. Thanks for sharing!
What a good idea! My seeds normally get killed off because of the cold whether and nothing germinates. Thanks.
You are so welcome!
I live in montana and one day the weather is 60 then is 20 below. My question is : wouldn’t the constant warm and cold trigger germination? Also second question. Can you use these for sweet peppers that need to be in Soil that is 75-80 degrees? Thank you.
Your best bet would be to wait until close to spring, but winter sowing should give you a bit of a head start and you won’t have to worry about hardening them off.
I saw you’re a Maine girl, I am too! 🙂 Shared this on my facebook page.
Welcome Mainer friend! And thanks for sharing 🙂
I am too! Cant wait to try this! So excited to see we can do this here. I want to garden economically and it doesnt get much better than this!
I am too! Cant wait to try this!
I am not sure that planting in plastic is safe because of the leaching out of the chemicals. I usually start my plants in peat pots. Do you have any information on this subject?
I assume that the milk jugs need to be the clear (soda type), or semi transparent sort (water type), not the white ones (milk type), correct?
As long as it isn’t opaque, you should be find. You are correct, though, that those light-block bottles won’t work.
So we cannot use the regular milk jugs then? They need to be mostly clear? Also so the seed just freezes in the wet soil and then in when it starts to warm up, it thaws like the ground outside does?
Correct and correct. Light block bottles won’t work since they do just that, block light. Standard “milky” milk bottles work just fine though. As far as the seeds freezing, that’s okay. The idea behind this method is that the seeds take their cue from nature and begin sprouting when nature says it’s time. They start sooner than they would normally because your container heats up like a mini greenhouse.
LOVE the idea!! Will work excellent here in cold Norway. 🙂
I don’t know much about gardening in Norway, but cold and snow are no problem with this method. Make sure you swing by on Thursday when I talk about how to winter sow for the various gardening zones. I’m not sure if yours work the same way or if they are a US thing, but it should give you some direction.
The easy way to make holes in plastic is poking it with hot soldering iron. That’s what I do anyway.
Why did I never think of that. Great idea!
Or the tip of a hot glue gun.
how many seeds do you, put in the milk jug and what time of the year would I plant, we live in Thomas,Wv
I was wondering how difficult it is to transfer The plants from the container into the garden without damaging them? Have you ever tried peat cups to plant in?
How many seeds per milk jug? Do I use the whole packet?
<3 this idea!! I've decided this year to just grow heirloom veggies so I can save the seeds and know there are no GMO addititves. I plan on getting the containers I've been saving for cloches and use them now to start my seeds. What a wonderful site! Thanks for sharing and answering all our questions. 🙂
I really think im gonna give this a try. Sure would take alot of stress off of me! Thank you! Sooo glad i found you
I really think im gonna give this a try. Sure would take alot of stress off of me! Thank you! Sooo glad i found you
This will help so much as I have cats that eat all my seedlings that I start inside. I love that you dont have to harden the plants. I also deal with high winds most of the time. Going to have to get creative on how to keep them from blowing away. I need to look up my zone. Central KS. Ill be checking back on Thursday! Thanks!
Cats and small children are the reason I was instantly drawn to this method.
I would put some rocks in the bottom of the milk cartons, and then the soil, to help keep them stable in the wind!
What kind of soil do you use? Do you purchase a bag from the store? My ground is too frozen to dig anything!
I’m excited to try this!
I buy starting soil from Home Depot. I keep planning to store soil from my garden and creating my own mix, but I haven’t done it yet.
Want to try this but live in southwest New Mexico. Any ideas on my zone.
I’ve gotten a lot of questions regarding zone-specific guidelines. I am going to address all of that on Thursday, so be sure to check back.
What about super cold nights? In February, we normally have a few 20 below zero or colder nights – won’t this kill the seeds before they can germinate?
They are protected in their little greenhouse. Before they begin germinating (which is triggered naturally by the warming weather), they are dormant, so no harm will come to them.
I live in Northern BC zone 2b . I am wondering if we can do this here as well. Our winters are pretty cold and smow is usually gone by May. We usually don’t plant until Mid May.
I’ve gotten a lot of questions regarding zone-specific guidelines. I am going to address all of that on Thursday, so be sure to check back.
you never really explain what to do with the lids. could you please elaborate?
Sorry I didn’t elaborate. You remove the caps to allow for the rain and snow to water the soil inside.
Last Fall, I made a hoop tunnel garden (3′ x 15′ x 20’+). What would you suggest for planting seeds in this?
Last season, I had volunteer tomato plants in my garden, that sprouted the same time I was planting purchased plants from dealers. Both plants produced tomatoes at the same time, making me wonder why I spent $$$ on the larger plants. This year, I will plant more interesting tomato seeds. I am so looking foward to planting your way. Thanx much!
You can certainly start plants and seeds earlier when you use a plastic hoop setup. Not knowing the specifics of your growing area, I can’t tell you for sure when a good time to start would be. I would suggest sticking a thermometer in the covered area and tracking the temperatures for a bit.
I have been doing this for years and it does work well. You can skip the ice and drill if you use an ice pick or awl to make the holes in the top and bottom of your jug. I have also used 1/2 gallon oned, but did not have good luck with quart size as they tip over too easily.
Great tips Liz! Thanks so much for sharing.
I live in central Mississippi, zone 7 I think. Would like more info. on Winter Sow planting for my area, especially what can be planted and when. Thanks.
I’ve gotten a lot of questions regarding zone-specific guidelines. I am going to address all of that on Thursday, so be sure to check back.