Order seeds & Sowing instructions

Most native plants need their seeds to go through a moist, freeze/thaw cycle to break open  their outer shell and allow the seed to germinate (also called cold moist stratification or CMS). This cycle is naturally provided by our winter and spring seasons. 

Plants that require stratification cannot be simply sown directly outdoors  either in the soil or in pots in the spring.

Quick step-by-step videos are available on our YouTube channel

You can also print winter sowing instructions by scrolling at the end of this page.

Germination is more successful if seeds are sown in pots, rather than directly in the ground. When you sow in pots, you can protect the seeds from being eaten by birds, dug up by squirrels or blow away by the wind.

To ensure that the proper cycle is followed, seeds should be sown very late in fall or into the winter, to make sure that once the seeds freeze they don’t thaw until the spring.

In the Ottawa area, that means sowing seeds no earlier than about the end of November. Seeds can also be sown later in the winter as well, into January.

• Workspace where you can work with soil and water
• Flower pots/plastic/ containers / beverage jugs/deep clamshell containers  (the plastic needs to be sturdy enough to withstand our winter weather
• Potting soil  (not peat moss or black earth) 
• Water
• Tray
• Seeds
• Waterproof permanent marker, oil-based paint marker, grease pencil/China marker
• Labels
• Window screens (optional)
• You may also need: scissors / box cutter / drill /duct tape

You can use any size flowerpots. Ideally, using pots of a similar size will make it easier to place a screen on them once they have been placed outside.

Make sure the pots have drainage holes in the bottom.

Put potting soil in the pots, leaving about ½ inch from the top.

Wet the soil thoroughly. You can also place the pots in water in a tray to allow the soil to absorb water from below.

You can use any plastic container that is about 3 to 4 inches deep, such as yogurt, margarine or sour cream containers.

Rinse out the containers and discard/recycle the lids.

Using a drill, box cutter or scissors, pierce drainage holes in the bottom of the containers.

Put potting soil in the containers, leaving about ½ inch from the top.

Wet the soil thoroughly. You can also place the containers in water in a tray to allow the soil to absorb water from below.

You can use any beverage jug, such as juice, milk or iced tea jugs, or soft drink bottles. The plastic must be translucent enough to let in light, so that the jugs act as mini greenhouses. The jugs do not have to be completely transparent, but they should not be opaque.

Rinse out the jugs and discard/recycle the lids.

The lids are not used and the jugs are left open so that rain and snow can fall into the jugs.

Using a drill, box cutter or scissors, pierce drainage holes in the bottom of the jugs.

About 4 inches from the bottom, cut the jugs almost all the way around, leaving a small piece attached to form a hinge. The hinge will make it easier to close the jug once the seeds have been sown.

Put potting soil in the jugs, leaving about ½ inch from the cut.

Wet the soil thoroughly. You can also place the jugs in water in a tray to allow the soil to absorb water from below.

You can use any clamshell container that is at least 3 to 4 inches deep and that has a lid.

Rinse out the containers.

Most clamshell containers have holes in the bottom and in the lid. Both are necessary. Holes in the bottom ensure proper drainage and holes in the lid allow rain and snow to enter the container.

If you are using clamshell containers that do not have holes, drill or cut holes in both the bottom and in the lid.

Put potting soil in the containers, leaving about ½ inch from the top.

Or put potting soil in small flower pots (make sure they have drainage holes) and put the small flower pots into the clamshell containers.

Wet the soil thoroughly. You can also place the containers in water in a tray to allow the soil to absorb water from below.

 Once the pots are prepared, you are ready to sow the seeds.

The general rule of thumb is to sow seeds to a depth that is the same as the diameter of the seeds.

Surface sowing

Some seeds are like powder or are attached to fluff. You would surface sow these seeds.

Sprinkle the seeds across the surface of the soil, spread across the whole pot.

Gently press down on the seeds to ensure that they make solid contact with the soil.

Gently sprinkle some water on the pots to wet the seeds.

Sowing just below the surface

Some seeds are slightly larger. They would be sown just below the surface of the soil.

Sprinkle the seeds across the surface of the soil, spread across the whole pot.

Gently ‘scratch’ the surface of the soil in a zigzag motion. This will displace a bit of soil to just barely cover the seeds. 

Or you can sprinkle a very fine layer of soil over top the seeds.

Gently press down on the soil to ensure that the seeds have solid contact with the soil.

Gently sprinkle some water on the pots to wet the seeds.

Deeper sowing

Some seeds are larger and would be sown deeper in the soil.

Place the seeds on the soil, gently press the seeds into the soil to a depth that is the same as the diameter of the seed, and cover the seed with soil.

Gently sprinkle some water on the pots to wet the seeds.

It is highly recommended to use two methods to label the seeds that you have sown. Labels can fade, be dug up by animals, or be blown away by the wind. Having two methods ensures that a back-up is in place.

An easy practice is to number the pots and keep a list in the house of the pot numbers and corresponding seed species that was sown in each pot.

Adding a second label inside the pots is also a good practice. There are many ways this can be done. One method is to cut strips from a yogurt container, write the number of the pot and the name of the plant on the strip, and place the strip into the soil in the pot. 

When labelling the pots and the strips, make sure to use a marker that will not fade. Good examples are Staedtler Lumocolor permanent waterproof marker, Sharpie oil-based paint marker (not the regular Sharpie markers which will fade), or grease pencils/China markers.

If you are using clamshell containers or beverage jugs, once you have your labels in place (both on the outside and inside the containers), you will need to make sure they are closed solidly.

Many clamshell containers have lids that snap closed. To ensure that the lids stay in place throughout the winter, use a small piece of duct tape to hold them in place.

To close the beverage jugs, use enough duct tape to go all the way around the jug to seal the cut.

The final step in winter sowing is to place the pots outside.

It is important to make sure that the pots are in a North or East facing spot. 

Pots placed in South or West facing spots are at risk of being killed by too much sun in the spring.

Make sure the pots are exposed to the elements. They should not be under a roof.

Place the pots right up against one another to help hold them in place so they don’t fall over. It is also possible to use a wood frame or bricks to hold the pots in place.

If you are using flower pots or plastic containers, it is a good idea to cover the pots with window screens. This will protect the seeds from being eaten by birds, dug up by squirrels or blown away by the wind. It will also reduce the risk of weeds growing in the pots.

If you place a screen over the pots, you can anchor it down with a stick, rocks or bricks.

Place the pots right up against one another to help hold them in place so they don’t fall over. It is also possible to use a wood frame or bricks to hold the pots in place

If you are using clamshell containers or beverage jugs, a screen is not needed.

You can now forget about your pots until the spring.

• How to build a simple hoop house cold frame for growing native plants outdoors, Blooming Boulevards
• How to transplant seedlings from trays into pots, Pollinator Partnership
• Micro-Nursery Q&A, Sundaura Alford-Purvis
• Native Plant Propagation: How to Set Up Indoor Grow Lights, Blooming Boulevards
• Planning a new garden? Start now - remove grass by smothering, Blooming Boulevards
• Seedling Native Plants Webinar, Muskoka Conservancy
• Seeds to Seedlings: Starting Native Plants from Seed, Pollinator Partnership
• Site Preparation for Wildflower Pollinator Gardens, Blooming Boulevard
• Thin! How to Rescue Overcrowded Seedlings, Blooming Boulevards
• Wild Plants from Seed: Propagating Eastern Canada's Native Vascular Plant Species, Graham Page & Kristl Walek 
• Winter Sowing Tips for Native Plant Seedlings, Nurture Native Nature
•  Pollinator Partnership and Blooming Boulevards provide an overview of all of the methods available to you.