This is a guest post from Gardens by Barby. I was intrigued when I read about this ingenious method involving winter sowing of seeds. Other methods prefer waiting until March to sow seeds, and involve heat lamps, a large designated space and more. I have yet to be overly successful with those methods. Inspired by this post, I raided my recycle bucket for plastic clamshell containers and started my mini greenhouses on my back deck…If I find success with this method I will have lots of annuals and perennials to plant in my gardens come spring.

Compulsive gardeners can get quite morose in the dead of winter. It’s one thing to pour over the new seed catalogues, dreaming about how those perfect flowers will look in your garden. But what gardeners really want is to DO something. Create, grow, nurture. We’re just itching to get out there.

In all my years of gardening, I had never heard of winter sowing until last fall. A friend bequeathed me with a garbage bag full of recycled jugs, bottles, clam shells and jars. She said I could use them like mini greenhouses for germinating my seedlings. What? How?

She grabbed a clear clam shell that once held a sandwich and instructed me to get some potting soil and some seeds. She cut some holes in the bottom and poked holes in the top. She wet the soil and filled the clamshell half full. I sprinkled some sunflower seeds on top, added a bit more soil, and sprayed it with water. We set it in a large planter on the deck. And that’s it. She said that come spring, the seeds will sprout at their own pace with virtually no effort on my part.

Well…. let me tell you that I suddenly envisioned the possibilities. No overloaded window sills, and no seedling rotations to ensure they all get some sun. No angst about who gets to be planted in February… March… or April. No dilemma about whether or not to lay out the bucks for lighting, heat mats, trays, and pots.

Could it be true?

So I dove right in and started to research. The term, “winter sowing” was coined by Trudi Davidoff in the early 2000s. She was looking for a solution to a problem. Too many seeds, too little space. It occurred to her that Mother Nature sows her seeds outside in winter, so perhaps she could do the same.

The idea of winter sowing is not new. Seed packets will sometimes instruct you to direct sow outdoors in the fall. These plants are adapted to winter conditions and have evolved to lay in wait in the cold before germinating in the spring. But the life of these seeds is precarious. Many are fated to fail due to, for example, predation or heavy spring rains.

Winter sowing changes the game. By sowing the seeds in a confined environment, they are protected from the vagaries of nature. Will it work with all seeds? No. It will NOT work for plants that come from tropical areas where they would never be exposed to cold. It WILL work especially well for seeds that require a period of cold stratification to come out of dormancy.

Step One – Prepare

Assemble and clean your containers. You should use either clear or cloudy plastic containers that will hold 3 to 5 inches (7 to 12 cm) of potting mix, allowing room for sprouting seedlings to develop at least two sets of true leaves. Remove and discard labels and caps. Cut drainage holes in the bottom.

Slice the container about three quarters of the way around the middle, leaving a ‘hinge’.

Step Two – Sow

In a large bowl, moisten your potting mix. Spoon it into your containers and pack it a bit to remove air pockets.

Sprinkle your seeds on the potting mix and press them into the soil. Sow more than you need, but not so many that they will be too crowded. Cover the seeds with sifted dry potting mix. Note that many seeds require light to germinate, so don’t cover too thickly. Gently spray water to thoroughly soak the potting mix, but not to the point of being muddy.

Step Three – Label

Label your containers with species and date. There are several ways to do this. You may use a thickly-applied permanent marker directly on the container. (Note that it is common for the lettering to fade with long-time exposure to the sun.) You may simply write a bold number on the container and keep a list of the corresponding seeds in a safe place. OR you may write the information underneath the container so it is not exposed to the sun. OR you may insert a popsicle stick or other labeled item directly into the container. Some people do ALL of these things, just to be sure. You may then seal the top to the bottom with strong tape.

Step Four – Place Outside

Put your containers outside somewhere safe, perhaps on a table or along the edge of the deck. Keep in mind that you want them to receive snow and rain as part of the process.

As spring approaches, you will see condensation forming, which is exactly what you want. The ventilation will allow air and water to circulate in your little greenhouses. Watch to ensure they do not dry out as the sun gets stronger. Use a gentle sprayer to add water through the vent.

Step Five – Monitor

Watch for your seeds to sprout. As the weather gets warmer, be aware of them overheating. Move them into a shadier area if necessary. If your seedlings are threatened by a cold snap, cover them with an old blanket, or move them into an unheated garage, or even the trunk of your car. Do NOT move them into your house.

As Trudi Davidoff says,
“ … the warmth fosters fast top growth which may not be as cold hardy as the seedlings that sprouted outside in early spring weather. If you must protect your seedlings, give them tough love, no coddling. Sometimes a few seedlings will falter and die, but those that survive grow on to be hardy plants.”

Step Six – Plant

Ideally, transplanting should be done while the seedlings are small. If there are only a few seedlings, gently pull them apart to plant individually. If there are many seedlings, gently pull apart hunks of seedlings and roots. Plant these hunks into a nicely prepared bed and let nature thin out the weaker seedlings. Make sure everyone is watered in well and then give a light feeding.

You should expect that your winter-sown seedlings will be more robust and tolerant of weather conditions than nursery stock. As with any new plants, monitor them daily and keep them moist until established. Give them a regular boost with a quality fertilizer and feel great about the money you saved on flats and potted plants.

This is my first year trying Winter Sowing. I’ve read everything I can find on the subject and gleaned much through the stories and experiences that others have shared. I am both nervous and excited!

Have you tried winter sowing? What plants did you try? Would you do it again? Please share your experiences in the comments.

Until next time ….