Winter Sowing: A lesson about growing


Photo by Evie S. via Unsplash

Author: Shazia Y. Hussain, Master Gardeners of Ottawa-Carleton; published with permission

I am an avid gardener and a lifelong learner. My garden is an ongoing experiment, as well as a source of awe and pure inspiration.

Even before I put it to bed in the fall, I find myself planning and dreaming about the upcoming year. I reflect on which plants have flourished and which ones have flopped. I am always on the lookout for practical ways to improve my gardening practices. For instance, although I have had success growing different types of seedlings indoors, I have found the process cumbersome. Then I discovered winter sowing.

What Is Winter Sowing?

Winter sowing is a seed-starting process that emulates the natural cycle of cold, moist stratification. The freeze-thaw cycle helps seeds break dormancy in order for them to germinate.

Seeds may be sown in a variety of repurposed containers. However, two-liter plastic pop bottles are the most commonly used. These are clear, vented, and have drainage holes added. They are placed outdoors for the winter, so the seeds will undergo a period of dormancy. The containers protect the seeds from being ravaged by critters and from being displaced by precipitation.

Germination is ‘kick-started’ once the weather becomes warmer and there is more daylight. The seedlings should develop healthy, strong roots before being transplanted directly into the ground.

Trudi Davidoff, a gardener from New York, introduced winter sowing. She developed the method in response to a lack of indoor space for germinating seeds.

What Can Be Winter Sown?

Look for key words and clues found on seed packets: self-sows, reseeds, refrigerate, freeze, require pre-chilling, stratify, cold (moist) stratification, sow outside in late autumn, can withstand light frost, are cold-hardy, and can be directly sown early.

Examples: Agastache foeniculum (anise hyssop), Aquilegia (columbine), Rudbeckia hirta (black-eyed Susan).

Plants with common names that have the word wildflower or weed in them, such as Eupatorium maculatum (spotted Joe Pye Weed) and Asclepias tuberosa (butterfly weed), are great candidates for winter sowing.

When to Winter Sow?

Between December and February, sow seeds requiring cold stratification. For example, Delphinium elatum (delphinium) and Lupinus perennis (wild lupine). Around mid-March, sow hardy annuals such as Centaurea cyanus (bachelor’s buttons) and Papaver nudicaule (Iceland poppy).

Between late March and early April, sow tender annuals like Zinnia elegans (zinnia), vegetables such as tomatoes, and herbs such as Lavandula angustifolia (lavender).

How to Winter Sow?

Gather materials:

  • Containers:
    As long as the container chosen has a translucent cover, will house at least 8 cm of potting soil, and is one in which drainage or venting occurs. Although holes may be made, there are many options. Some examples include: clear, green soda bottles; white milk jugs; takeout platters; clamshells; aluminum takeout pans; even gallon Ziploc bags and comforter bags! The number of containers you need will depend on the quantity of plants you want to grow. Although any clear container may be used, the most common ones are large pop bottles and distilled water containers. I asked my local Buy Nothing group on Facebook and community association to save bottles for me. People are very generous!
  • A drill or any pointed tool, like an awl, for making drainage holes
  • Scissors, scoops, and any useful devices for planting seeds
  • Seeds, organic potting soil
  • Plant labels and garden markers
  • A spraybottle or mister with water
  • Duct tape

Container preparation steps

To simplify instructions, a pop bottle will be used as an example.

  1. Ensure that the bottle is clean and dry.
  2. Turn the bottle over and drill enough holes for good drainage. Make some more holes at the top, close to where the bottle cap was. This will be for ventilation and an entry point for precipitation.
  3. Make a horizontal cut across the middle of the container, leaving the ‘hinge’ attached.
  4. Add about 10cm of pre-moistened soil.
  5. Plant the seeds following the recommendations for seed spacing and correct depth. Gently mist the soil with water.
  6. Write the name of the plant on the label and include the date sown.
  7. Seal the bottle by affixing duct tape around the middle part cut in Step 3.
  8. 8a) Place the container outdoors where there is some light. It does not have to be in a sunny spot. Ensure it is not disturbed by pets, snow shoveling, etc.
    8b) Remember, the location should allow the container to be exposed to the elements (i.e., rain, snow, and wind). Precipitation will enter through vent holes, creating condensation and providing the moisture needed.
  9. In the spring, seedlings will emerge. On warm days, open the cover. Regularly check to see that the seedlings do not dry out. Water when needed.
  10. Thin as required.
  11. Remove seedlings and transplant them into the ground.

Benefits of Winter Sowing:

It allows you to re-use what you already have at home.

  1. It helps to save money, as electricity or grow lights are not needed.
  2. Eliminates the need to use indoor space for pots.
  3. Yields a greater number of plants grown in a smaller space.
  4. The watering frequency is significantly reduced.
  5. Hardening off is not required, unlike seedlings grown indoors.
  6. Plants will not become ‘leggy.’
  7. It allows gardeners to get a head start on the growing season.
  8. Encourages children to participate in gardening activities.
  9. Keeps people engaged in a season where many are prone to depression.
  10. Is simple, easy and fun to do.

Some Considerations

Depending on how many plants you intend to grow, preparation can take a few hours.

When I have not thinned out or separated seedlings over time, I have observed that they have become crowded and root-bound. The effect is that it has taken them another full growing cycle to recover.

Winter Sowing…Yea or Nay? Definitely yes, but with the caveat of showing self-restraint.

The first year I learned about winter sowing, I sowed 50 to 60 containers, totaling hundreds of different plants! I was thrilled with the notion of accumulating many new flowers without spending a ton of money! However, when it came time for me to transplant these, I was overwhelmed.

I am a work in progress, just like my garden. Last year, I winter-sowed 20 containers and could have blissfully added more. However, I realized that it would mean less time for essential tasks in the garden. These experiences have given me a better appreciation of the expression, “Just because you can does not mean you should!”

I will soon put my garden to bed while dreaming and planning for next year.

I already have a list of native plants that I would love to add to my yard.

There are no mistakes, only growth gained from learning opportunities.

Visit a Botanical Garden For Unique Experiences.

More on Gardening Calendar