Winter Sowing Workshop

  • Saturday January 27, 2018
  • 12:30 to 2:30 p.m.
  • St. Peter’s HARRRP community center, 705 Main St. East Hamilton (side door)
  • free, but please pre-register via email: or phone: 289-788-1345

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Winter sowing (WS) is a way to germinate seeds outdoors in mini greenhouses made from recycled containers and bottles. It’s a somewhat controlled way to do what Nature does when seeds fall and germinate naturally in the garden, allowing the freeze-thaw cycles and gradually increasing sunlight to break seed dormancy and produce healthy, robust seedlings which are generally ready for planting out by mid-summer. Winter sowing allows gardeners to grow LOTS of plants without the expense of indoor racks, heat, and artificial lighting.

Which seeds to winter sow?

Any perennial plant species that are hardy in our climate zone (zone 6) can usually be winter sown. Annuals that self-seed or “volunteer” in gardens are good candidates.

Native plant seeds are excellent for winter sowing. In fact, some seeds actually require the cold-moist stratification processes that winter sowing provides. Native plants are preferred by the pollinator insects whose numbers are in decline. Do not grow or plant invasive species.


Seeds Require

  • soil (seeding mix). For tiny seeds use fine-screened seeding mix. For larger seeds use pro-mix or triple mix. The depth of soil in the container should be about 4 inches.
  • moisture. The soil mix must not be allowed to dry out. So you’ll need to visit your containers regularly once they thaw out. A spray bottle is handy to moisten the soil surface but not dislodge tiny seeds. You can bottom-water but don’t keep the soil sopping wet. Plant roots need air and saturated soil has no air pockets.
  • air / venting / room to grow. Air must be allowed to escape from the “greenhouse” or else the heat buildup, even after a few minutes of sunshine, will cause the soil and seeds to cook. Remember that hot air rises. If you’re using clear plastic as a greenhouse cover, cut several small slits in the top. If you’re using a pop bottle or similar, leave the cap off. If you’re using a grow-dome, cut holes in the clear plastic lid. The seedlings will need room to grow, so ensure there are several inches of space between the soil surface and the greenhouse “roof”.
  • drainage. Containers must have holes or slits cut in the bottom so excess rain / water can drain out.
  • light. The soil surface must receive sunlight—but not too much. Diffused light is best. To prevent overheating you may want to put your containers in the shade until the soil is thawed and germination is possible. Then move the containers to a sunnier place where the gradually increasing light levels in the spring will promote germination.

Supplies (bring to workshop)

containers. Whatever container you choose, make sure it can hold at least 4″ of soil. Here are some ideas:
– mushroom tubs with ziplock bags
– large clear plastic milk jugs
– any container with rigid sides with a bottom that can be punched or cut

soil-less mix. This is your “dirt”. Don’t use garden soil (it’s frozen anyways…). Bring a bag of commercial seeding mix. William Dam sells an excellent fine mix. For larger seeds you can use all-purpose mix. “Potting mix” is okay for large seeds but usually has too many large chunks that cause trouble for tiny seeds

We will have bags of Premier PGX ultra-fine seeding mix available on the day, for sale at cost. Approx. $3 a bag, cash only.

Scissors and sharp small knife. For cutting containers “lids” and making drainage holes

tape. If you’re using milk jugs you need duct tape. If you have smaller containers, the tape is for writing the plant name. White or yellow electrical tape works if your marker is black. Black tape works if you’re using a white or light-coloured paint marker.

marker for labelling the containers. You need something that won’t fade with exposure to sunlight or water: “Industrial” sharpie, paint pen, soft pencil, or china (grease) pencil.

Something to create a mini-greenhouse Large ziplock bags work with smaller containers. Large clear salad containers often work. Milk jugs are excellent– they can be cut to form flip-top lids and the open top is small enough to prevent deluges from entering but large enough for proper ventilation. The Internet is full of suggestions for winter sowing containers. Whatever you choose, make sure there is at least 2″ clearance between the “roof” and the soil and the roof/lid will not collapse on top of the soil when rain or snow collects on it.

seeds Bring your own seeds please. Others may have some to share but don’t assume. To see if your garden wish list is appropriate for winter sowing, check for seed lists. If you are using seeds that do not include sowing instructions, please do some advance research or come prepared for an internet search on the day.

sturdy boxes or something to carry home your filled containers. This is crucial! It’ll be a big and possibly heavy load. A tote box can work. A large shopping bag with a reinforced bottom can also work.