The Persephone Period, a term coined by renowned organic gardener Eliot Coleman, is used to describe the period of time where the number of daylight hours drops below 10 hours per day. You can easily look up the number of daylight hours for your area by using the USNO table of daylight hours. Here in southern Tennessee this covers December 1 through January 12. During this time, little to no plant growth occurs. If you timed your fall planting right, your plants should be just shy of maturity before the onset of the Persephone Period. When the daylight hours once again reach 10 hours, you’ll notice a little growth starting again, giving you a continuous winter harvest and a great head start on early spring greens. I’m having very good success with my North Pole and Merlot lettuce (pictured above), Vates kale and Early Bloomsdale spinach planted last fall.
Here is an excerpt from Eliot Coleman’s book, The Winter Harvest Handbook, giving some history behind the name “Persephone Period.” Humans have long had their own way of understanding the changes in day length and its affect on agriculture. Early Greek farmers, whose practical experience added mythical stories to astronomical fact, knew intimately that the power of the sun and the length of the day are the principal influences on agriculture. They created the myth of Persephone to explain the effect of winter conditions. As the story goes, the earth goddess Demeter had a daughter, Persephone, who was abducted by Hades to live with him as his wife in the netherworld. Demeter would have nothing to do with this and threatened to shut down all plant growth. Zeus intervened and brokered a deal whereby Persephone would spend only the winter months with her husband, Hades. Demeter, saddened by her daughter’s absence, made the earth barren during that time.