Winter Sowing in Southern Ontario

Winter Sowing is a trendy way to start seeds in Southern Ontario. Trudi Davidoff is credited with being the creator of this method, and what drove her to it is the same reason I keep using it year after year.

What is Winter Sowing?

It is a method of seed starting that doubles as a cold moist stratification method. Winter Sowing repurposes common recycling containers, typically larger bottles (juice or milk jugs), to serve as small “greenhouses” for each batch of seeds. These are stored outside, in the winter; exposed to the rain, snow and cold winter weather.

Why use Winter Sowing?

The reason Trudi Davidoff began with winter sowing, is the same reasons I rely on it year after year: Limited indoor space.

Many urban dwellers have limited indoor real estate (800sq ft is the Toronto condo average, with 2,000sq ft for low-rise homes). Now that many households are working and potentially teaching their children from home due to Covid, real estate is at an even greater premium. Being able to delegate seedlings to an outdoor area, without having to baby them is ideal for busy parents.

Other reasons include: the need for cold moist stratification, no ideal window locations, no additional equipment required such as grow lights, no hardening off process.

What seeds work for Winter Sowing?

The list is surprisingly long! Nearly all seeds will work with this method BUT it may not give you the head start you need for a full harvest. (The reason we start seeds indoors is to ensure a plant reaches maturity and we can harvest before our first fall frost.)

When reading plant labels look for the following terms to figure out which plants work best:
“cold moist stratification” (the term “stratification” in general), “requires pre-chilling” and if the plant is from Southern Ontario “native” “wildflower” “weed” (as in jewel weed), or “self-sowing”. Terms referring to Spring or Autumn such as “can handle light frost”, “cold hardy”, “direct sow in early spring/late autumn”.

How to do Winter Sowing?

1. Collect Containers.
   In my experience, the bigger the jug the better. Tall and skinny containers, like a 2L soda bottle, has a tendency to tip over. Seedlings tend to outgrow (height) take-out food containers. They can be translucent or frosted but you want to avoid completely opaque containers. Remember, we are making a greenhouse and need to let sunlight in. Get rid of the lid, the top hole will allow for airflow and for rain/snow collection.

2. Cut/punch drainage holes into bottom.
   Mother Nature is going to be watering this for us, and she doesn’t modify based on container size, so drainage holes are a must to prevent a swampy mess within the jugs.

3. Slice jug in half, leaving a “hinge”.

   The slice allows us to evenly fill with soil and sow seeds, and the hinge allows easier sealing of the container.

4. Add your pre-moistened potting mix of choice.
   You’ll hear me mention ‘pre-moistened’ whenever I talk seed starting. The reason is that potting mix, when it’s dry, rejects water. Water will just run right through it without absorbing. So I start with a bowl, add my soil & water and let it soak the moisture up. You don’t want it sopping, and you can squeeze out any excess, but by presoaking you ensure that the soil will act “appropriately”.

5. Sow your seeds.
   Whether they are dusted on top of the soil or tucked under a light layer depends on the seed. Check your seed packet for the appropriate method.

6. Seal up the jug with tape.
   Close it up so that it resembles the original jug again, and seal with tape. I use duct tape as I find it survives the elements well.

7. Label

   Unless you like surprises.
   I write directly on the jug with a sharpie marker. I’ve found it lasts until spring without the sun making it illegible but you may find that labelling tape and sticking it under the jug works better for you.

8. Place it outside

   Make sure it’s in a level spot, exposed to rain and sun (not under any canopies or overhangs). Mother Nature takes it from here!

9. Sneak a peek.

   Trust me, you’ll be peeking into the top hole more times then you’ll publicly admit. It’s OK. We all do it. There’s often a squeal upon the first sight of green too.

Winter Sown spinach being transplanted into gutter garden in April.

Once your seedlings have a set of true leaves, you can up-plant if they are crowded. Otherwise, once their final “homes” in the garden are ready, transplant them.

Due to its simple and low cost methods, Winter Sowing is one of the best ways for beginners to dip a hand into seed starting. Tag us on Instagram @buying_thyme if you try this out!