WINTER SOWING 101
What is it and Why is it So Popular?
In a nutshell, winter sowing, or winter seed sowing, is sowing seeds indoors in the winter in mini greenhouse-like containers, like milk jugs or other recycled containers, and setting the containers outside in the winter elements until Mother Nature germinates the seeds in the spring. That basically is the winter sowing method.
Benefits of Winter Sowing
- There are very few things in life that are SO easy and work SO well as this does!
- No figuring out sowing dates for each specific seed.
- No indoor grow lights or set up. You sow the seeds in the winter sowing containers and you put them outside.
- When seeds germinate outdoors, the seedlings and plants they will produce are naturally hardier and their rate of survival is greater.
- It gives you your gardening fix in the middle of winter!
Why is Winter Sowing becoming so Popular?
Very simply. It works!
What kind of seeds can I sow with the winter sowing method?
Flowers, vegetables, and herbs! A further explanation later.
First, a Bit about Timing
It is generally accepted that you can begin to winter sow anytime after the Winter Solstice when the days are at their shortest and typically the temperatures are at their coldest.
The problem that I found with starting as early as the Winter Solstice is that here in Zone 6 Ohio, we often get some unexpected warm stretches in December. If I put the containers out that early and we get a warm spell, the seeds may germinate too early and the coming cold temperatures will kill the seedlings.
By planting a bit later when the threat of those warm-ups is passed, I can be confident that the seeds won’t germinate until spring, as planned.
For more specific timing for Zones 3 through 7 where the weather gets cold enough to winter sow, here is a general guideline for times to sow each category of seeds.
Zones
Zone 3
- February - Perennials and Hardy Annual
- March - Herbs
- April - Frost Tolerant Vegetables
- May - Tender Plants
Zone 4
- January - Perennials and Hardy Annuals
- February - Herbs
- March - Frost Tolerant Vegetables
- April- Tender Plants
Zone 5
- December/January - Perennials and Hardy Annuals
- January/February - Herbs
- February/March - Frost Tolerant Vegetables
- March/April - Tender Plants
Zone 6
- December - Perennials and Hardy Annuals
- January - Herbs
- March - Frost Tolerant Vegetables
- March/April - Tender Plants
Zone 7
- December - Perennials and Hardy Annuals
- January - Herbs, Frost Tolerant Vegetables
- February - Tender Plants
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Want to know more about planting zones and ways to extend your season? Try this book.
My Winter Sowing Method
After ten years of trial and error, my technique for winter sowing is based on sowing the seeds in two stages. One for the perennial seeds of cold-season plants, and a later one for annual flowers and warm-season plants.
You can, of course, sow continuously through the winter months, but keeping it to a simple two-phase sowing system is much easier for me.
The First Sowing
(8 to 10 weeks before your average first frost date)
For us here in Ohio, it's January 15 to February 15.
My first sowing is always around January 15 because there are seeds, like perennials, that need weeks of cold weather before they become stratified and can germinate in the spring, they are the first ones to be winter sown.
Examples of my first sowing include:
Flowers: Lavender, Veronica, Phlox, Rudbeckia, Delphiniums.
Herbs: Rosemary, Sage, Oregano, Parsley, Mint, Thyme.
Vegetables: Brussel Sprouts, Broccoli, Cabbage, Kale, Lettuce and Beets, Salad Greens.
If you're not sure if your seeds need this cold treatment, you can look on your seed packet for words like “self-sow,” “direct sow in the fall,” “direct sow in early spring,” “cold hardy,” “cold stratification,” as well as any perennial plant.
The Second Sowing
(4 to 6 weeks before your average last frost date)
For us here in Ohio, that's March 1 through April 15)
My second sowing is on March 1. The second sowing is done more towards the Spring for annual flower seeds and warm-loving plants in general. You could sow these in the first sowing earlier, but you risk the chance that the seeds become waterlogged over the long winter, and I don't like to take the chance.
Examples of my second sowing include:
Flowers: Annuals like Marigolds, Coleus, Cosmos, Zinnias.
Herbs: Basil, Dill.
Vegetables: Tomatoes, Peppers, Squash, Cucumbers.
A Note about Vegetables.
Root vegetables are just easier to direct sow into the garden rather than have to transplant them through winter sowing. I don't winter sow root vegetables and vegetables that are easy to direct sow like peas and beans.
One word of warning. The seeds of some warm weather veggies can sprout well in the spring, but in colder climates, they will sprout later and there may not be enough time to get a harvest. Sowing indoors may still be necessary for long-season plants in colder areas.
About the Winter Sowing Containers
I have had my best success with winter sowing in milk jugs and don't use anything else.
Why do most Winter Sowers Prefer Milk Jugs?
- Milk jugs will let light in. (Only use the clear ones.)
- They are tall enough to give the seedlings plenty of headspaces to grow if you can't transplant right away.
- Having the lid off will let in just enough rain and snow to keep the soil moist.
- They're wide enough for your hands to scoop out those seedlings.
- They're plentiful – (At least at my house!) If not, have people save them for you and save them from the landfill.
Some gardeners clean them and reuse them again. I put them in the recycle bin. I am able to collect plenty to start with fresh ones each winter.
Other container possibilities.
As long as the container has these features, they will work:
- Must be plastic, or at least sturdy enough for winter use.
- Must have a clear top so the light can get through.
- Must be able to hold 2-3” of soil and have some room for headspace. The plants may get 6” tall if you leave them in there long enough.
- Must be something you can put several drain holes in the bottom. (and top if there's no lid spot)
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Examples of these include:
- Ice cream buckets
- 2-liter soda bottles
- Clear plastic restaurant food containers
- Deli container
- The list is endless.
Preparing the Container
We'll use a milk jug for the instructions.
First, THROW AWAY THE LID OF THE MILK JUG OR 2-LITER BOTTLE! The lids have to be removed to let moisture in when it's placed outside!
Cut the milk jug around three fourths of the jug like the picture. I start with a knife to break the plastic and then use scissors to circle around to the handle.
Cut drainage holes in the bottom. In a milk jug I put at least five. You can use anything that works; a drill, a knife, some people use a soldering iron.
If you're not using something that has a lid that you can take off, like a deli plastic container, you will need holes also in the top of the container to let rain and air through.
Bend the handle back to open the milk jug. You're ready for the soil and seeds.
About the Soil
You will find various opinions on what type of soil works best for winter sowing. I've always used normal potting soil (the cheapest I can find) and have had absolutely no problems.
They usually contain a little fertilizer which helps the seedlings grow while they're waiting on me to get to them.
How much soil?
Two to three inches of soil in the bottom of the milk jug is plenty. You just want enough soil to germinate the seed and help the seedling along until you transplant it into its final spot in your garden.
If you do a lot of jugs (I do a hundred or so), soil gets expensive. You don't need more than 3 inches and you don't need the expensive stuff.
Important Step – Moisten the soil thoroughly before sowing the seeds so as not to dislodge the seeds later!
Sowing the Seeds
Since the intention is to transplant the seedlings out in the garden and not grow them very long in the winter sowing container, you can space the seeds much closer than you normally would.
How many seeds you put in each container will depend on:
- What kind of plant you're growing.
- Whether you intend to transplant them very small or wait until they're larger. I prefer to give them room to grow inside the milk jugs. Spring is a very busy time and my attention gets lost in other projects and before I know it, they're 6” tall. (The stems are also stronger by this point and easier to handle when transplanting.)
Plant the seeds at the depth recommended. On average, the sowing depth of a seed is one and a half to two times the width of the seed. For very small seeds, just place them on top of the soil and tamp down to get soil contact.
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All about Winter Sowing
Sealing the Container
Here are a few options:
Good ole' Duct Tape. One piece in one area should do it, usually across from the handle vertically. I found if I use more duct tape than that, I have a heck of a time taking it off later.
I have also done the bread tie trick. Put a hole in the top and bottom half and close with a bread tie. I have found this to work better than the Duct Tape, but it's a lot of work when you have a lot of containers.
Labeling
Some people consecutively number their containers on the outside with a magic marker or paint pen, and then have a chart noting which seed is which number.
Some people write the name of the seeds directly on the outside of the container. Markers will fade in the sun; paint pens are great!
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Word of advice
Whatever you write on the top half, also write it on the very bottom. Why? One, the sun won't fade it as quickly when it's labeled underneath.
I tend to cut off the entire top half as the seedlings start to grow and need more air circulation and light, and when I did that with the label only on the top, well, you can imagine. A lot of seedlings look alike when they're that young!
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When do you usually plant your winter sows? The rule around here is about mothers day for regular plants. Does this mean I can plant earlier because they have been outside for months already? When you plant, do you use fertilizer? Help. Thank you
ReplyDeleteWinter Sowing is sowing them in milk jugs and putting them outside for Mother Nature to germinate later. Step by step in the article.
DeleteWhen to sow is determined by your seed packets. If the seed packet states to start indoors 6-8 weeks before the last frost, you count back 6-8 weeks from that date; that is when you sow your seeds. I love milkjug gardening!
ReplyDeleteNo, you cannot transplant these milkjug plants any sooner than your store bought plants. The milkjug serves as a mini greenhouse and protects your plants through their growing season. These plants are still susceptible to frost and would die if exposed to frost. The nice thing about these plants is they do not require hardening off if you have had the milkjugs open for a few days. Hope you enjoy milkjug gardening as much as I do. Good luck!
ReplyDeleteThanks for your answers, Suzy-Q!
ReplyDelete1/21/2022 Sun. 12:49am.. Hello Susan I love your article and I'm wondering if this method can be used here in zone 9 San Antonio, tx.? Also would it be too late for me to start it now? Thank you for your insight and Be Blessed!
ReplyDeleteLove the article, going to try it here in Zone 7B, I might run into warm days too
ReplyDelete