How to winter sow

Most native plants need their seeds to go through a process to cool and warm the seeds so that their outer shell softens, enabling them to sprout (also called cold moist stratification or CMS). This cycle is naturally provided by our winter and spring seasons. Plants that require stratification cannot simply be sown directly outdoors either in the soil or in pots in the spring; they must be winter sown.

Instructions

Timing: Winter sowing should be done between December and February.

Quick step-by-step videos are available in the How to winter sow playlist on our YouTube channel. Written instructions are also available below the video.

Written instructions

You can download and print a one-page infographic with these instructions in English or French.

  • Fill a flower pot (or juice jug / clamshell container / plastic container) with potting soil.
  • Make sure the pot has drainage holes at the bottom.
  • Water the soil and press down firmly on it.
  • Sprinkle a package of seeds into the pot.
  • For most seeds, gently stir the seeds into the soil with your finger or a small stick.
  • For “surface sow” seeds, press the seeds onto the soil surface.
  • Use two methods to label your seeds, an oil-based marker is ideal.
  • Place the pots outside in a North or East facing area (never South).
  • Make sure rain and snow can get in the pots (i.e. not under an overhang).
  • Optional: cover the pots with an old window screen or netting.
  • Leave the pots outside until the spring.
  • Once the snow melts, make sure the soil does not dry out.
  • Make sure the pots get morning sun exposure.
  • Once the seeds have germinated and the seedlings reach a few inches in height, they can be transplanted in your garden.
  • Very small seedlings can be repotted into larger pots to provide more space for root growth before transplanting in your garden.
  • If many seedlings are growing tightly together in the pot, place a clump of soil and seedlings in a small basin of water and gently stir it around to separate the roots, then either repot the seedlings or transplant them in your garden.
  • Once you have transplanted the seedlings in your garden, keep them watered until they get established (usually a couple of weeks).

Additional resources