By Jackson Pittman
As we come closer to the winter solstice, it's not uncommon to find farms and gardens closing shop up for the cold, short days ahead. In fact, even our own farm has virtually stopped producing altogether aside from our sporadic batches of chicken eggs and an ever-producing aquaponic system. But, do things always have to be this way? Is it impossible for us in Zone 4 to maintain production as the days get chillier? Do we have to cast away the thought of crop production just because the temperature drops a couple measly degrees because designing a full functioning growing area with a heater is beyond our price range? The answer to all of these is: of course not. In fact, we can make the most of these colder months in surprisingly simple ways, not by working against the colder shorter days, but using them to our advantage. As Eliot Coleman describes in TheWinter-Harvest Manual: Farming the Back Side of the Calender, harnessing frosty conditions for plant production can be done by using simple plastic structures and veggies that grow better under lower temperatures.
The technique Coleman describes in The Winter-Harvest Manual is one which uses simplistic, greenhouse-like structures to grow cold-hardy vegetables in abundance. These structures are neither heated nor extremely insulated. In fact, they are merely plastic covered hoop-houses, or high tunnels. The outer layer of plastic over the high tunnel should have an anti-drip coating so moisture condenses as opposed to forming drops, to allow more light in and reflect the heat coming from the soil at night. The hoop houses are aligned to the east-west axis, and, instead of being attached to a foundation, the hoops are attached to a pipe rail the length of the greenhouse so they can move easily in a straight line like a sled. This allows two adjacent sites for the greenhouse, one to cool heat-loving crops in the summer, and the other to heat cold-hardy plants in the winter. It also allows the off season site to be refreshed by half a year of exposure to fresh air and elements each seasonal cycle.
The real crucial part of Coleman’s winter-harvest technique lies in row covers. He prescribes “any lightweight translucent fabrics that allow air and water to pass through.” Although heavier fabrics create more heat, they block out around 35 percent more sunlight than lighter fabrics, and allowing air and water to pass through is much more substantial when it comes to cultivating healthy and tasty vegetables. The plants don’t need the extra heat of a heavier cover anyway because the combination of the plastic covered hoop house and the row covers creates a twice-tempered climate, which creates extra humidity to fight the frost and breaks the wind, both substantial parts of keeping the plants healthy.
Another reason why it’s better have a lighter cover which ventilates more efficiently is because since the cold months have less sunlight the plants need the most they can get. To cold-hardy plants, a couple degrees below freezing isn’t as detrimental as factors like wind-chill and poor ventilation. Another beauty of these covers is that they are easy to manage—they sit on flat-topped wire wickets 12 inches above the soil, and they are also inexpensive and large pieces are easy to remove and replace for harvesting and accessing the plants. The fabric should be clothespinned to the wickets at the ends of each row to prevent the fabric from sagging; frost damage can occur when the fabric droops down to the plants below but if properly maintain no damage will occur.
The final ingredient for successful winter harvesting lies within the plants themselves. The vegetables to be planted basically depend on the latitude (which determines amounts of sunlight). Coleman, who lives in the 44th longitude up in Maine, plants everything from salad crops such as green and red lettuces, arugula, chard, spinach watercress and things of that nature, to potatoes, carrots, beets, turnips, leeks… the list goes on. The plants chosen basically depend on the regional and seasonal temperatures. It is important to keep in mind that the plants need to be sown very precisely because the days get shorter instead of longer as we work the other side of the calendar. The crops should reach a decent size by the time the length of day drops below 10 hours. After that they will pretty much stop growing except when harvested until the day lengths begin to lengthen again and they receive a glorious revival.
Well, hopefully this helps you imagine a world where the growing season is year-long, and we will be there growing alongside with you. While it may take a while to actualize it due to technical factors remember the winter has been around as long as the sun has shone and we are all working together to grow tasty and healthy vegetables!