This advice will help you learn how to grow winter vegetables, and benefit from fresh harvests even during the dark days of the Persephone Period.
If you studied Greek mythology, or you’re a gardener who’s heard of the “Persephone Period,” you might remember the story of the daughter of Zeus and Demeter. Persephone was abducted into the underworld by Hades. No crops grew during the period of Demeter’s grief and anger while she desperately searched for her missing daughter. Demeter (goddess of agriculture and harvest) finally appealed to Zeus for her daughter’s return. Prompted by hunger among the people, Zeus complied. But Persephone admitted to being tricked by Hades into consuming a few pomegranate seeds. For eating the food of the underworld, she was condemned to reside in that place for a number of months of every year. To this day, Demeter withholds fertility and plant growth while her daughter stays underground — hence, the season of winter.
The Persephone Period in Your Garden
This tale is why gardeners today refer to the “Persephone Period” or “Persephone Days” (terms coined by author and expert winter gardener Eliot Coleman; read his technique for “Growing Plants That Survive Winter Outside“). In the Northern Hemisphere, this period begins in fall when the days grow too short to effectively sustain the growth of most plants. Seed companies know this well, and they send peppy emails in midsummer reminding gardeners, “It’s time for fall planting!”
Contrary to popular belief, not only cold temperatures limit vegetable growth; day length is also a factor. Most plants need at least 10 hours of sunlight per day for active growth. The Persephone Period begins with the last day that has 10 hours of sunlight before the winter solstice. As a rough rule of thumb for gardeners in the Northern Hemisphere, daily sunlight usually drops below 10 hours in mid-November and rises above 10 hours in about the first week of February. Knowing these dates will allow you to plan a winter garden by planting so vegetables will achieve maturity above that 10-hour-per-day threshold. You can generate a daylight/darkness table for your area on the website of the U.S. Navy’s Astronomical Applications Department.
Sowing a fall garden can allow gardeners to reap autumn and winter harvests, and it has the added benefit of diminished insect predation. Additionally, you can harvest during the following spring and summer from overwintered plants, such as garlic and winter wheat.
Because both temperature and day length are reduced in fall and winter, crops will need longer to mature than in spring or summer. Below that 10-hours-per-day threshold, plant growth nearly stops. Before the Persephone Period begins in your area, crops need to be nearly 100% mature for fall and winter harvesting and at least 75% mature for overwintering. If you’re starting seeds in fall, first check the maturity date on the seed packet, and then count backward to the point of desired maturity to determine when to plant.
How to Grow Winter Vegetables
When deciding what to plant, look for cultivars marketed as cold-hardy or frost-tolerant. Johnny’s Selected Seeds has categorized types of vegetables for winter gardens based on successful winter production. The easiest to grow and most productive (Tier 1) include spinach, kale, claytonia, and baby-leaf brassicas. The next easiest (Tier 2) are bok choy, arugula, chicory, cilantro, and broccoli raab. The more challenging (Tier 3) tend to be radishes, carrots, bunching onions, Swiss chard, lettuce, and turnips.
Most vegetables suited to fall gardens need 60 to 90 days from planting to harvest, which means you’ll need to plant them between mid-August and mid-September for them to mature before the Persephone Period begins. If you plant later, the vegetables won’t have enough time to reach 75% maturity for overwintering or full maturity for harvesting before growth slows dramatically.
Soil temperature can be a factor when sowing a winter garden. Sometimes, the soil is simply too warm for direct-sowing in late summer, such as with lettuce and spinach; these crops do better when started indoors. Late summer can also be quite dry, so make sure your newly planted garden receives sufficient water.
After the crops are established, and when frost threatens, you’ll need to protect them so you can harvest as desired. The protections you put in place will keep the plants alive and fresh, even though they’ve mostly stopped growing. If the plants are close to maturity (75%), then protecting them throughout winter will allow them to spurt to maturity when the Persephone Period ends.
Root crops prefer 4 or more inches of mulch to keep them safe during hard freezes. Aboveground plants will be harmed by heavy mulch, so protect them with a low tunnel or a cold frame when the temperatures fall below freezing. (Low tunnels can increase the interior temperature by more than 20 degrees Fahrenheit.) The heavier the cover, the less light can penetrate — and interior temperatures will rise enough on warm, sunny days to damage the plants — so vent the cover or frame when the outdoor temperature is above 50 degrees.
To prevent frost damage from occurring, only harvest plants when outdoor temperatures are above freezing.
Alaska and the Persephone Period
Alaskan gardeners famously grow enormous vegetables: cabbages 3 feet across, cantaloupes that top 65 pounds, and carrots so sweet they taste like they’ve been sprinkled with sugar. Is Demeter working overtime?
Once again, daylight length is the critical factor. Alaskan summer days can see as much as 20 hours of sunlight. This enormous boost of photosynthesis results in more plant material — which is why so many veggies grow to enormous size — and a sweeter taste. Smart gardeners also use cultivars uniquely suited to their special climate, including a maturity period that fits within the short growing season, often less than 105 days.
Commercial farming in the Matanuska-Susitna Valley began as an experiment in the 1930s. Farm families from northern states (such as Minnesota, Wisconsin, and Michigan) were encouraged to settle on land set aside for agriculture. Although this colonization faced a lack of infrastructure and other problems, the hardy farmers who remained learned that certain vegetables grew extraordinarily well there and were of superior quality. In fact, Alaska-grown vegetables are so outsize they can seem like caricatures — but they’re real.
The Persephone Period applies to Alaskan gardens too. Fall gardening is a race against the cold, and only short-season, cold-hardy crops sown during July or August will be successful. The Persephone Period begins around mid-October for most Alaskan locations.
Understanding the Persephone Period is the key to a successful winter garden, whether you live in Alaska or the Lower 48. You’ll reap the rewards of harvesting fresh produce when the days are short and snow covers the ground.
Grow Lights: Pushing Persephone
The Persephone Period can be artificially delayed through the use of grow lights, but their uses are limited.
Bulbs for grow lights differ from regular lightbulbs in a number of ways. Regular lights are designed to illuminate a room, and that’s all. Grow lights (either LED, fluorescent, or high-intensity discharge) produce light in the range of 400 to 700 nanometers — the blue and red spectrum, specially geared to plant growth. (Red triggers flowering; blue contributes to photosynthesis.) Grow lights also produce a high wattage, or brightness. Both factors contribute to optimal conditions for plants to convert amino acids into sucrose, along with other chemical processes associated with photosynthesis.
While grow lights will boost your plant’s growth, they’ll also boost your electrical bill, so this must be factored into the cost of extending your winter garden’s growing season. Grow lights are also more expensive than standard lighting options because of their specialized nature.
It’s possible to push back the onset of the Persephone Period long enough for transplants to achieve maturity in a greenhouse — helpful if you planted fall veggies a bit too late in summer. Grow lights can be used all winter for indoor plants, such as herbs or salad greens. And, of course, grow lights will permit you to start indoor or greenhouse seedlings especially early, before the Persephone Period ends.
Patrice Lewis has practiced self-reliance for almost 30 years. She has experience in small-scale dairy production, food preservation, animal husbandry, and more. Follow her at Rural Revolution.
