How to Wintersow
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Starting seeds indoors may save money, but it can be a major undertaking. You have to have grow lights and space to set them up; you have to stay on top of watering and repotting as everything grows; and then, when it’s finally time to take your plants outdoors, you have to harden them off and hope that they survive transplant.
Being a fan of all things simple, I’ll be skipping all of that and wintersowing for the fifth year in a row.
What is Wintersowing?
Wintersowing is outdoor seed starting. Basically, you make mini greenhouses out of milk jugs and other empty food containers; fill them with a few inches of seed starting mix; plant your seeds; water them; put the lid back on; and stick them outside for the winter. They’ll germinate at the right time, and your plants will be better adapted to your climate than any plants that you started indoors or bought at the store. Don’t you love when the easy way is actually the better way?
I usually start saving my milk jugs in December. With a family of four, it doesn’t take long to accumulate them. Then, I do my planting in December and January. There’s zero urgency with wintersowing, so I just do it when I have time. The process couldn’t be easier.
How to Use Milk Jugs to Wintersow
What You’ll Need:
Milk jugs, with lids removed
A knife or scissors
A hole punch
Seed starting mix
What You Do:
Use a knife or awl to poke drainage holes in the bottom of your milk jug.
Cut the milk jug open four inches from the bottom. Leave an inch uncut at the back of the jug to create a hinge.
Use a hole punch to make two holes in the milk jug on the corner that’s directly across from the handle. This will give you a place to insert a twisty tie, so you can close your greenhouses. I’ll show you that in a bit.
Fill the milk jugs with two to three inches of seed starting mix.
Then, plant your seeds following the instructions on your seed packets. I usually plant nine seeds in each milk jug greenhouse.
Be sure to label all of your milk jugs, so you don’t forget what’s planted inside. I recommend using a black permanent marker for the job. The sun tends to fade anything else out (even colored permanent markers). One year we used a blue permanent marker, and all of my labels vanished. Not fun to sort out.
Water your seeds deeply. Then, use a twist tie to close your milk jug greenhouses. This will keep the wind from blowing them open, and keep curious animals out.
Then, place your mini greenhouses outdoors in a sunny spot. Check on them occasionally to see if they need water, and your plants will be ready for planting when spring gets here.
The milk jugs do a really good job of retaining moisture, so they shouldn’t require much watering or attention from you. I’ve tried other containers (berry boxes, take out containers, etc, and they just don’t work as well as milk jugs.
Oh, and don’t sweat it if your jugs get covered by snow. It won’t hurt them a bit.
Here are some broccoli starts from 2012. I got a 100% germination rate out of this container. Can’t complain about that! I’ll try to remember to post pictures as this year’s seeds start to do their thing.
Have any questions about wintersowing? Already a fan of wintersowing? I’d love to hear from you.
I must learn to ask you about all things garden before I begin. I am bookmarking this for next year and probably for a comparison study this year. Thanks for the tip. I’m just the lucky one who gets to live next to you and get the hands-on information straight from the horse’s mouth.
I used close to your idea for 28 years in Milwaukee WI. I always had a beautiful garden because I cut the bottoms off the milk and water jugs and placed the tops over the plants to keep the cold and snow off of them. I want to Thank You for the idea to use the whole jug. I never thought of it.
You know, it would be great to marry the two ideas — make the milk jug greenhouses to wintersow your seeds. Then, cut off the tops, and use them as garden cloches (as you did) to protect your tender plants when you’ve first planted them.
What state are u in? I usually start tomatoes, peppers and zinnias inside every year. I’m in Wisconsin and am going to try this. I suppose I should get a moving on it soon!
Hi Kris, I’m in TN, but it’ll work just as well in Wisconsin. Most seeds benefit from being exposed to cold temperatures, and even if your milk jugs get completely buried in snow, they’ll be just fine. I know of one blogger who wintersows in upstate New York. I’ve seen pictures of his jugs absolutely covered in snow.
Hi Erin! I have started seeds in pots and put them out early in cold frames. I’ve also done some overwintering of spinach that begins growing again when conditions warrant. I’m trying overwintering beets and carrots I planted late last year in a cold frame. I will let you know how they do. I will definitely try this method too. It sounds a lot easier than using the cold frames!
I’ll be interested to here how all of your overwintering goes. I have some parsley that’s planted close to the house. It’s survived all winter, and I didn’t do anything to protect it. If it just hangs on for a few more weeks, I should be golden.
Will this winter seeding work in a cold climate line northern NJ? Love you article!
Yep, I know people who wintersow in NY with great success.
So…when your plants are ready in the spring – do you just gently separate the starts and plant them in your garden? Is there a trick to do this without damaging the roots?
Yep, that’s exactly what I do. They’re usually pretty big by the time I transplant them, so the damage is minimal. I’d say it’s no worse than what happens when you slide a plant out of a store-bought container.
Hi Erin, what month do you begin to wintersow?
I usually start my wintersowing in Jan/Feb, but you can start it as early as you’d like.