Winter Sowing
A popular northern climate alternative to indoor seed starting, I first learned about winter sowing from an enthusiastic and passionate gardening and volunteer friend back in 2012. It’s safe to say, she was well ahead of the trend, and while I never got into it, I thought of her every year as I carried on with my indoor rituals and she set her rows of jugs out with glee, abandon, and confidence.
No one system is the right system for all gardeners, and that’s what makes this a great alternative for those who are new to gardening and want to try growing flowers from seed but find indoor seed starting overwhelming. It’s especially effective for native seeds, things like milkweed, echinacea, and blazing stars that are pollinator power houses but need exposure (a few months’ time) to cold and damp conditions in order for the seed to break dormancy and germinate.
Winter sowing can also be as simple as sowing annual seeds outside and letting them germinate when conditions are right. Our heavy self-seeders do just that each winter. For us that’s larkspur, viola, and chamomile, annual flowers with small seeds that we sowed indoors once — and they just keep coming back on their own!
Poppies, snapdragons, and calendula are three other flower seeds that would do well sowed outdoors in winter. And I mean setting the seeds out in late fall before the snow flies or in early winter if you’re in a milder climate — and letting them take cues from the soil and moisture as to when to germinate. Most of these seeds also need light to germinate, and that’s why sowing directly on bare soil or a prepared bed in fall makes this a set it and forget it task.
I will see chamomile, larkspur, and snapdragon seedlings in early April in our garden every year. It even seems like the chamomile and larkspur germinate UNDER the snow because they have true leaves by the time the snow recedes. It’s garden magic, to be sure.
Sowing native seeds is also done by winter sowing. This is how we do it. Damp potting soil and evenly distribute the seed mix throughout. Toss like sprinkles on a cake over a prepared area, preferably with snow on the ground AND snow about to fall to cover them up and protect against nibbling birds. The snow really helps you see where you’ve already sowed seeds so you don’t throw too much seed in any one place. The end-game is usually a 12”x12” plant spacing.
For those that want more control over where and when native flowers germinate on their property, winter sowing in jugs is the perfect project. First, you need to mimic this cold stratification by placing them in damp potting soil inside their fridge for 60 days before planting. Outside, nature simply goes about its business and this is done with the passing of the seasons. And we can capitalize on nature and the benefits of these micro greenhouses and produce seedlings a good bit earlier than if they were simply seeded on top of snow and left to their own devices. I think of this as an intermediary between indoor seed sowing and direct seeding our gardens.
The benefits of this alternative seed starting method include:
Less resources than indoor seed starting (no grow lights, shelves, or heat mats needed)
No need to harden seedlings off
A modest jumpstart on the growing season over direct seeding, which means earlier blooms and yields
Here’s how I made mine.
Cut gallon jugs about in half, with the bottom tall enough for several inches of potting soil.
Cut about 95% around the container. You want the back to hinge open with ease. I left about an 1.5 inches (4cm) attached on the back side.
Do as I say, not as I do. Using a drill for these bottom drainage holes would be easier. I used the box knife, because I was trying to make this as accessible as possible for people who don’t own a drill. It worked, but required a different kind of muscling than a drill would involve.
Fill with damp potting soil in the bottom 3” or so. Space seeds a reasonable distance apart. These are calendula and 1” spacing will work fine for teasing apart at transplant time. Smaller seeds like larkspur, alyssum, and snapdragon were more densely sowed and I may need to thin them out a bit.
For seeds that needed covering, I then added more potting soil on top (calendula). I did make a mess watering them in, but I wanted this very gentle stream. Doing this in the kitchen sink would have been smarter.
The final step is to close the containers back up and seal them shut with duct tape. The caps are disposed of for both air flow and allowing moisture in over the weeks and months. Set outside in a snow back, preferable a western or northern aspect (I broke this rule and these are on our south-facing deck, which is where I’ve always done this).
Share your experiences with the community! I know of at least one very enthusiastic MGG winter sower who has transitioned almost all her flowers to this method. Brassicas and lettuce which are both cold hardy are also excellent seeds to winter sow. I hope to hear from folks in the comments about how they’ve used this and what their favorite veggies are to winter sow.
