Winter sowing is an economical, easy way to start plants from seed. This technique is ideally suited to seeds that require cold stratification (a period of cold & moisture) to break dormancy. Winter sowing should be done, as its name suggests, in the winter. Anytime from late December through early March is ideal.
Which Plants to Winter Sow?
This method is ideal for many of our native prairie plants and hardy perennials, as it replicates the natural seeding process for these plants (mature seeds drop, overwinter, and germinate in spring). It can also be used for annual flowers such as snapdragons, marigolds, nasturtium, alyssum, cleome, violas, and annual poppies. Even cool-season vegetables such as kale, broccoli, cauliflower, cabbage, chard, spinach, and lettuce can be started using this method, although it is not a good choice for warm season vegetables such as tomatoes and peppers.
How do you germinate seeds using the Winter Sowing method?
Materials for Winter Sowing
- Clear plastic milk jugs are popular and work well. Other containers that can be used include clear plastic juice containers and take-out trays with clear lids.
- This method works especially well for seeds that require a cool moisture period in order to break dormancy. This includes many of our Native Wildflower Seeds.
- Seed started growing medium
- A quality seed starting mix is the best growing medium for winter sowing, but a well-drained potting soil can also be used. Do not use garden soil.
- Sharp knife
- Duct tape
- Permanent marker
DIY Winter Sowing Steps
Step 1: Prep Container
Remove the cap from the milk jug and dispose of it. Cut milk jug ¾ of the way around, leaving the last part attached as a hinged lid.
Step 2: Drainage Holes
Cut, poke, or drill drainage holes in the base of the container.
Steps 3 & 4: Sow Seeds
3. Fill the base of the container with 2”-3” of seed starting mix/potting soil.
4. Moisten the soil. Smooth/level the surface of the soil.
Step 5: Sow Seeds
The general rule of thumb for planting depth is not to plant any deeper than twice the diameter of the individual seeds. However, because each type of seed has specific germination requirements, I recommend reading the seed packet or looking for the specific germination instructions online.
Step 6: Seal Container
Use duct tape to re-seal the cut sections of the container once you’ve sown your seeds.
Do not seal the top of your milk jug.
Step 7: Labeling
Use a permanent marker to write the name of the plant on the outside of the container.
I also recommend writing the name on a plant label inside the container in case the outside writing fades.
Step 8: Go Outside
Place your container in a sunny spot outdoors, where it will receive precipitation (not under eaves).
What to do with your Winter Sows when spring arrives?
When the weather starts to warm up in the spring, check your winter sown containers regularly.
Once seeds germinate and seedlings begin to put on size, you will want to remove the lid. Continue to monitor the seedlings after removing the lid. Water when rain is not adequate to maintain moisture levels and prepare to re-cover the plants if the temperatures drop too low.
Transplant your seedlings into your garden!
If you’re using this method to start hardy prairie plants, I recommend labeling each baby plant once you transplant them into the ground. Even something as simple as a Popsicle stick or plastic knife beside each seedling will be of great assistance in differentiating weeds from desirable plants once you need to begin weeding the area.