(Updated for 2020.) BELIEVE IT OR NOT, I start my summer garden in January and February, using a neat trick called “Winter-Sowing.” Winter-sowing is an outdoor method of seed germination (invented by Trudi Davidoff) which requires just two things: miniature greenhouses (made from recycled water and milk jugs) and Mother Nature. You can winter-sow your way to a beautiful garden, too…for pennies. Here’s how:
Make a Greenhouse. You can make a greenhouse from any number of clear or translucent plastic containers. Like other winter-sowers, I use recyclables, including gallon-size milk and water jugs, and, on rare occasions, 2-liter soda bottles. With jugs and bottles, use a pen-knife to cut around the middle, almost all the way through. The uncut half-inch or so will serve as a hinge.
Next, punch out drainage holes in the bottom of the container. I use a Phillips screwdriver, heated over a flame at the stove, to facilitate the hole-punching job. Punch out also a few holes along the top portion of the jug. These extra holes provide ventilation. Ventilation is the key to preventing excess heat from building up in the greenhouse, and baking the seeds to death. Remove the cap from the jug or bottle. Watch me make and plant a miniature greenhouse.
Select the Right Soil. It is essential to use a light, fluffy, well-draining potting mixture. A commercial peat-moss and perlite mix is fine. Pour the soil, preferably to a depth of 2 to 3 inches, into the container.
Water the Soil. Moisten the mix thoroughly, and then let it drain.
Sow the Seeds. Sow your seeds on the soil surface. Cover the seeds with more soil, when necessary, in order to achieve the proper planting depth. Gently pat the mix down, so that seeds and soil make good contact. Then replace the lid, and secure it with a strip of duct tape, as illustrated above.
If you live in a cold climate, as I do, plant your perennial and hardy annual seeds first. Should these sprout during a weird warm-spell in winter, they will not be harmed. Wait until March to plant tender annuals. More details here: What to Winter-Sow…& When.
Remember to Label! For each sowing, indicate with a permanent marker (or a paint-pen) the seed variety and date sown. Do not omit this step, for there is nothing worse than finding, in spring, dozens of miniature greenhouses brimming with seedlings, and not knowing what they are!
Bring the Greenhouse Outdoors. Your planted and labeled greenhouse is now ready to brave the outdoor elements. Select a location that is safe from strong wind, but where sun, rain and snow will be freely admitted. My assorted greenhouses go on a wire-mesh patio table, out of the reach of Lily the Beagle, who would otherwise knock them over. For further protection from tipping, I place them in a large plastic box, with drainage holes melted in the bottom.
Relax! Now sit back and let Nature take over. As the weather chills and warms, your seeds will freeze and thaw. These natural actions loosen the seed-coatings. This is why advance soaking or nicking of hard-shelled seeds, such as Morning Glories and Sweet Peas, is not necessary when you winter-sow.
At the first kiss of spring, but while nights are still freezing, seedlings will begin to emerge. This is the time to check for water. Open the tops, and if the soil appears dry, moisten thoroughly but gently, so as not to disturb tender root systems. Then close the tops. On warm, sunny days, I like to open the tops for hours at a time, and let the seedlings enjoy the fresh spring air. The tops, of course, are closed at dusk.
I can’t tell you how advantageous winter-sowing can be. Last year I produced an entire garden’s-worth of perennials this way (far too many, in fact), without the need for light-systems, heating devices, or seed-starting kits. And, unlike windowsill-germinated seedlings, which more often than not are frail and spindly, winter-sown seeds grow up to be strong, sturdy plants, completely prepared for glorious careers in the open garden.
If I were you, I’d give winter-sowing a try. Honestly, it’s the easiest, most cost-effective way to achieve a beautiful garden.
Other food and garden fun: