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Winter Sowing Lets You Get A Jump Start On Spring. Here’s How

This seed-starting hack turns DIY mini greenhouses into an outdoor germination factory.

Three boxes in the snow, filled with empty, repurposed plastic bottles filled with dirt to start seeds for winter sowing

Winter sowing upcycles plastic containers like water jugs, salad clamshells, or pop bottles into mini greenhouses that allow seeds to germinate outside when the conditions are right.

When the polar vortex howls outside your door and the snow is deep enough to swallow a dog, gardening might seem like a summer fever dream. But winter sowing, an easy, no-fuss method to start seeds created by American gardener Trudi Greissle Davidoff, makes it possible to swing into spring a little early.

Winter sowing upcycles plastic containers like water jugs, salad clamshells, or pop bottles into mini greenhouses that allow seeds to germinate outside when the conditions are right. Whether you’re into flowers or veg, winter sowing can give you seedlings with so little effort even the most neglectful plant parent can manage.

Valerie, who asked that her last name not be used, is one of the moderators of a winter sowing Facebook group that teaches Davidoff’s method, sees huge benefits: “It’s easy to do, not expensive, low maintenance, and you get great germination! You can do it in winter and have seedlings in spring without the hardening off [acclimatization] process and no expensive equipment.” Since it puts plants out in the elements, no precious indoor space needs to be sacrificed, and seedlings don’t need to be defended from toddlers or pets.

The first time Valerie tried winter sowing, her husband was skeptical and said she hoped she wouldn’t get too disappointed, but she was anything but: “I had more seedlings than I knew what to do with!”

Ready to give winter sowing a try? Valerie’s advice to first-timers is not to overcomplicate matters: “The method is simple and straightforward, and meant to be easy.”

left, a packet of seeds and a container of dirt on a table; right, a container filled with sprouting seedlings

Try leafy greens (kale, chard, lettuce, bok choy, spinach, etc.) and hardy herbs (cilantro, chives, or parsley) for your first attempt at winter sowing.

Winter sowing timing

Winter sowing season starts after the winter solstice on December 21. Native perennials (like milkweed or coneflower) often need 60 to 90 days of cold weather exposure, so they’re planted when there are many cold nights to come. You can sow all your seeds at once, though some gardeners wait until a couple months before their last frost date to sow tender annuals (think tomatoes or basil), as this helps avoid unseasonable temperature swings.

What can you winter sow?

The easiest place to start winter sowing is with hardy annuals (e.g., plants that can survive a frost, like kale, peas or strawflowers). Seed packages will often say these can be planted out before the frost. Try leafy greens (kale, chard, lettuce, bok choy, spinach, etc.) and hardy herbs (cilantro, chives, or parsley). But people also winter sow beets, peas, pumpkins, grasses, snapdragons, coneflowers, and more: anything can be winter sown except tropical plants.

Winter sowing also doesn’t need to stop with cold weather, either: many people use this technique well into spring to get a head start on heat-loving crops like cucumbers or zinnias.

Keep in mind if you’re winter sowing perennials (plants that come back each year), they’ll be slower to grow and may not flower in their first year.

left, bottles with dirt filled with seedlings; right, the mature seedlings ready for transplant

Most plants will be ready to transplant into the garden when they’re two to three inches tall and have two to three sets of leaves.

How to get started winter sowing

Supplies

  • seeds
  • plastic containers that are at least 6 inches high and have a clear or translucent top. (try: 1 L bottles from water, pop, or juice; milk jugs; large plastic clamshells)
  • potting or container soil
  • packing or duct tape
  • scissors
  • something for labelling: permanent marker or grease pencil
  • something to make drainage holes (a drill, hot screwdriver, soldering iron, or a knife)
  • large bowl

Instructions

  1. Make holes in the bottom and top of your clean plastic vessel. These ensure water and air can get in and out.
  2. If using a jug or bottle, you’ll need an access point: cut an equator around the sides so it can be opened, leaving the top hanging by a hinge.
  3. Fill your bowl halfway with potting soil and add water until it’s moist but not soaked: soil should be wet enough that if you squeeze a fistful it will hold its shape.
  4. Fill container with 3 to 4 inches of your moistened potting soil.
  5. Scatter smaller seeds, or plant a few larger seeds. Check seed package for planting depth. Plant only one type of seed per container.
  6. Label the container, ideally on the underside of the container (where it won’t fade) and on a tag inside.
  7. Tape around the hinge if you cut one. If you’re using a jug or bottle, leave the bottle cap off to allow air and moisture in, but if you’re using something like a clamshell with a large opening, keep the lid on.
  8. Place outside somewhere the containers will get some sun and rain/snow. To keep containers from blowing around, nestle them in a low cardboard box. These won’t need much attention in deepest winter. If they get buried in snow that’s okay! Be patient: seeds may lie dormant longer than ones raised inside.
  9. Once your seeds sprout, check on them regularly to make sure they’re not drying out. (One easy way to check moisture is to lift the container: a dry one will weigh less than a wet one.) If they need water, set them in a shallow container of water and let it absorb, or simply overhead water them with a watering can or hose. (You don’t even need to open the containers.) If plants are looking crowded, pinch out a few to give the others more room to develop.
  10. Most plants will be ready to transplant into the garden when they’re two to three inches tall and have two to three sets of leaves. Consult your seed packets to see when transplants are safe to put out in the garden.

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