Organic gardeners can experiment with winter sowing methods to start seeds of hardy vegetables, flowers, and cover crops outdoors; no greenhouse is required.
Traditionally, there has been a time in the winter months when the gardener must appraise the success of the past season while the garden lies fallow. The duration of this fallow period varies according to growing region: some gardeners must satisfy themselves with bird watching and houseplant tending for six months; others must suffer only six weeks of chilly temperatures.
With a few supplies, gardeners can extend the growing season so far forward into late autumn and backward in early spring that the two growing periods extend into a continuum that forms the winter garden.
By starting seeds during the winter months, organic gardeners can give tender seedlings a head start while marauding pests are dormant.
The Winter-Sown Vegetable Garden
Gardeners can choose from a variety of flowers, vegetables, and cover crops for winter sowing. Even plants one might not normally grow from seed, such as trees, are good candidates.
Start by choosing plants that have a reputation for cold hardiness. In the vegetable garden, this would include collards, broccoli, spinach, Brussels sprouts, cauliflower, and kale.
The organic gardener can enrich the soil of next season’s vegetable garden by planting a winter-sown cover crop. Rye, vetch, and wheat are good choices for winter cover crops. In addition to enriching the soil when the gardener plows them under in the spring, winter cover crops hold soil in place.
The Winter-Sown Flower Garden
Many perennial ornamental flowers are suitable candidates for winter sowing, but even tender annuals can succeed in the winter garden.
If you have volunteer annuals in your garden each summer, these seeds may withstand cold or even freezing temperatures without impeding their germination. Examples include cosmos, marigolds, cleome, and verbena.
If you’re interested in starting a large perennial garden on a budget, look for clues in your seed catalog that denote winter hardiness. Seeds that require stratification are excellent varieties for winter sowing.
Stratification means that the seed requires a period of cold dormancy to germinate. Gardeners can find other clues to hardiness in the plant name. When reading the Latin name, look for terms like Siberica, Alpinus, Arctica, or Camschatsensis to indicate that the plant heralds from a cold region.
Providing Protection for Winter-Sown Garden Plants
With the exception of cover crops, winter-sown seeds require some protection to ensure germination success. Although winter sowing can involve a cold frame or a greenhouse, special equipment isn’t a must for winter planting.
Simply sow the seeds in finely screened compost in commercial flats or recycled containers, cover them with a vented clear lid, and place outdoors. Gardeners may note a feeling of temporary giddiness as they reclaim their windowsills for purposes other than seed starting.
The ideal spot is a sunny southern exposure, and is sheltered from the wind. Knock the snow off frequently to allow air and warmth-giving sunlight to enter the covered flats.
Mother Nature will tell the seeds when to sprout, so start looking for signs of life when daytime temperatures are consistently above freezing. Then, harden off the seedlings and transplant as usual.