It is the middle of summer and most of us are swimming in a sea of tomatoes, cucumbers, cut flowers, the works. The planting is done and harvesting and income over the next few months might determine how well many of us do for the whole crop year. So why am I writing, and Growing for Market publishing, an article on cropping during the winter?

Though I cannot speak for the editor, I always hope that GFM will publish some really bizarre stuff, maybe even from me, when the stream of articles from fellow farmers slows to a mid-summer trickle. I write this for three additional reasons: first, because I lament the global influx of vegetables into East Coast markets in all months of the year (yes, I am talking about those imported tomatoes in our supermarkets in August). I yearn for the era when more food really was grown locally, when we knew the woman who grew the best asparagus or the man whose strawberries were always great. The second reason I tip my hand about winter cropping is because my deep love for growing in the frigid months has finally overcome my fear that gazillions of other local growers will flood the market. I have finally realized that even hundreds of other local winter-cropping farmers could not begin to feed all the nearby city people gobbling mesclun and collards. Finally, August really is the time to ponder a fall planting season, and September is the time to start it.

Our farm defines winter cropping in three ways. From the marketing perspective, winter is that time of year when our nearest serious competitor is at least 1500 miles away from our local customers. Such a nice competitive advantage, that. Agriculturally, winter is that time of year when we dance around freeze, snow, and ice to harvest large quantities of adapted crops and sell them in a most welcoming market. And from an operations standpoint, winter crops are those sown between September and November, both in the fields and in the greenhouses, to bring in about 40% of farm income between late October and April. If any of these definitions appeal to you, please read on. If not, please return to the myriad duties of a market grower in peak summer.

I used to believe that winter cropping is simple, that to make it work required only a few steps and a few changes from summer cropping. Now, after periodically failing due to my complacency or oversimplifying assumptions, I realize that winter cropping mandates a whole package of practices. I stress this systems framework because I’ve seen a lot of failures, not only my own, in winter cropping. The failures nearly always stem from bad timing, from inappropriate soil management followed by too much precipitation, or from use of non-cold-hardy seed. But other factors in winter cropping can sap your spirits or your bank account, and so need to be addressed as well.

Our winter cropping system
We have two large greenhouses (totaling 5800 square feet) and 14 to 20 acres of fields that are planted to winter crops every year. The farm totals 104 acres, with 54 of these cultivated at some point annually. The greenhouses look like many other intensive mesclun factories, with wide harvesting beds of diverse greens running the lengths and alternating with narrow walkways (I’ll briefly cover greenhouse management later). The fields are for me more interesting. It is from the fields that the highest quality and, potentially, the huge yields come. It is also where it is easier to fail and where knowing your crops and using a systems approach really count. The fields are pretty level but with some low spots and ridges. Winter sees 4-6-foot wide beds of direct-sown cash crops alternating with 8-foot wide traffic rows planted heavily to clovers, vetch, and rye (our nitrogen and tilth sources for the warm season crops that will follow). The beds average 650’ in length and run north to south for contour purposes. Prevailing winds are strong and are usually westerly. Our cold-season unprotected cash crops are mostly brassicas: 4 cultivars of radishes, rutabagas, and turnips, totaling only an acre; 12 cultivars of kales, collards, mustards, and Asian greens, on between 7 and 13 acres; and about 5 acres of arugula. The rest of the cultivated acreage is in strawberries, perennials and overwintering annuals for warm-season cut flowers, and a large amount in either winter wheat or a winter fallow. We rarely have more than a half-acre of field lettuces past December, as nearly all winters see major freeze-kill of even the more hardy cultivars. Brassicas and cover crops rule.

Climatic limitations
Winter cropping is clearly not for every site. While well-managed greenhouses can be profitable far into the north, and our own greenhouses are very important players, our production and this article is about both protected and open-field winter cropping. I can only advocate the open-field component for USDA zones 6 through 10, a wide U-shaped swath covering much of the coastal, southern, and western US (our farm in Maryland is in zone 7). In the cropping system we use, heavy snows, ice, and freezes occasionally force the field crops into full dormancy, and we pick only from the greenhouses at that point. But the field crops survive to grow vigorously –and to be very harvestable—after the first thaw. For zone 6, this could be in March or April. For us, after years of using practices fitted to the market goal of winter sales, all of our field brassicas are harvestable after nightly hard frosts and 30% are harvestable with only the leaves and top 1/2 “ of soil thawed (i.e., with deeply frozen ground underneath).

While cold-season cropping is a strange idea to many, it has long been used by country people in suitable climates. People didn’t always have shipped-in lettuce from the Sunbelt, and many of the weeds we now fight were brought over by the European settlers to stave off winter scurvy or to act as early spring tonics. A great book that every prospective winter cropper should have is the reprint of Peter Henderson’s Gardening for Profit (available from Seed Savers Exchange, 563-382-5990). Henderson, farming and marketing in zone 6 between the Civil War and the early 1900s, was a master at integrating protected and unprotected winter crops on a very large scale. More recent authors also cover the topic, albeit with a heavier dependence on greenhouses than we have.

Right for you?
There is a lot of excitement about season extension among farmers and researchers who strive to serve the farm community. I greatly admire GFM, though, for printing counter-arguments (as Letters to the Editor) to the whole idea of extending our harvesting and sales periods. Farm work is a real grind, and maybe we need that winter down time to rebuild ourselves. I say this from experience. Our operation harvests and sells in every month, but a big part of me agrees with those who critique this nonstop production approach. Cropping all the time means that we earn income nearly every week of the year. It means that our customers very loyally stay with us. Both wholesale and retail seem to view us as miracle workers (“What?! Arugula when it’s this cold outside? I’ll take all you can give me!”). But it also means that we are hustling all the time and that our farm and our bodies are always under pressure. We lack the extended down time that lets other farmers undertake large construction projects, tune up their tractors, fix barn roofs, or vacation with loved ones. Instead, we have to fit in all those things around an intensive planting, harvesting, and delivery schedule. The big pluses are steady income and loyal buyers and the big minus is no time to regroup. You really need to weigh these factors before taking on large-scale winter cropping. On the other hand, small experiments in the cold season are inexpensive: 1-2 hours of labor, and $25 spent on seed, and you’re done with at least the September part.

What has made us into such devoted cold-season farmers, though, are two final variables. Winter crops and markets are much more reliable than summer ones. Our farm has turned a profit and has grown in every year we’ve been in business. But in two of those years – one an extremely bad drought, the other a year with 72 inches of rain, rain, rain – it was only the winter crops that made up for poor summer sales and kept us in the black. I am risk-averse. I treasure any crops that always work and that are easy to sell.

The final factor that has kept us in winter cropping is passionate devotion to outstanding flavors. Winter greens are like August tomatoes: at their absolute peak of quality. Tender frost-bit collards, tat soi that’s so sweet my daughter picks and gobbles it grit and all, Chinese mustards whose nose-tickling pungency is balanced and succulent rather than overwhelming, and cold-silvered arugula that is as perfectly composed and utterly complex as a Rhone wine in a vintage year – these are the stellar foods that we cannot produce in May or the warmer seasons. The market is flooded with insipid or harsh greens that never see any frost or freeze, and we are impassioned growers of what foods should be. That appreciation and passion make the winter wind seem a lot less biting, the winter grind a lot less disheartening.

Field crops
There are vegetable crops from at least five families that can reliably make it all the way through winter: the brassicas, or cole crops; the chenopodes (spinach, chard, and beets); the onions; the Apiaceae (carrots, parsnips, cilantro, etc.); and the Asteraceae (lettuces, dandelions, etc.). I hate gambling, and so focus both our winter cropping and this article on choosing winners from the families above.

Premier in durability are the brassicas. Across the globe farmers and backyard gardeners have and continue to use brassicas in the “off” season: collards in the Carolinas, winter cress as far north as New York, arugula and strap-leafed kales in Portugal and Italy, and mustards and loose-head cabbages in East Asia. Brassicas are the group that most likely come to the farmer with moderate to high levels of freeze-resistance already built in, and from this diverse group you are well advised to choose your first experimental plantings.

I need to present a few general cautions that the brassicas exemplify nicely. First, different crops and genetic lines present different responses to frosts and freezes. At the weakest are those with zero frost tolerance, for example some genelines of bok choy. At the next level are those that are good with frost but that handle freezes by essentially sacrificing all their leaves and going dormant until spring. Both these levels are of scant interest and won’t be discussed further. The penultimate level of cold tolerance are those genelines whose leaves get more sweet and succulent with repeated frosts but that will show “freeze hemorrhaging” at temperatures around or below 31( F (unimproved cultivars) or 24( F (our farm’s genelines). Freeze hemorrhaging is where the cells in part or all of the leaf burst, so the limp leaf shows large spots of translucent juiciness. Any freeze hemorrhaging makes the leaf unsalable, but this penultimate group includes some outstanding mustard genelines that bounce back into vigorous growth with the barest hint of spring. The final level of winter hardiness is shown by nearly all cresses, most kales, many of the collards, and a few of the Asian cultivars. Here, frosts and repeated freezes cause loss of only a few of the outer leaves, little or no irreversible freeze hemorrhaging, and slow but steady growth throughout all but our worst winters. After a night where temperatures have dropped to 10-22° F, the fields with these genelines look as if they they were zapped with herbicide: all leaves are wilted and worrisome. But this last group are the real professionals, and the antifreezes in their systems protect against any major losses. In 13 years of playing the cold-season game, we’ve had 4 really nasty winters in which this group went fully dormant (temperatures of 5-18° F, and repeated ice storms or heavy blizzards). But survival was 90-100% and March regrowth was amazingly good. Most winters, though, we harvest kales and the other professionals nearly every week, often only 2-3 days after the snow has been melted off by one of the brief thaws that are typical for our region.

The second caution I make in choosing brassica crops is that the open-crowned cultivars like most collards, kales, and many Asian leafy brassicas may be better than the tight-heading types, as you can easily see and cull out any freeze damaged individuals.

The last caution concerns the root vegetables. Most turnips, radishes, and rutabagas we’ve worked with are in the penultimate freeze response group. The leaves really take a hit at 23° F or so. But the roots look fine, right? Wrong. Many times you’ll be in an unpleasant gray area of quality, with some roots being superb and others with hemorrhage of the outer layers. Other varieties may develop an inner thin woody layer (essentially, a new skin) between the root core and the outer damaged layer. Any of these phenomena make the crop unfit for market. After big freezes, cut and taste a lot of roots, per cultivar, before you harvest en masse. And almost no overwintered root brassicas are fit for humans once they leaf out in true spring, at least in this zone.

That’s it for an overview of the brassicas. Play and experiment with these. They are the greatest companions and allies of the cold-season vegetable cropper. I stand in awe of their genetic strengths when Old Man Winter howls and I huddle in my Carhartts, wondering why on Earth I forgot to bring a hip flask out into the fields.

The second group, the spinaches, chard, and beets, have good cold tolerance but open-field plantings of these have not been profitable at our current site. Quality of cold-grown chenopodes can be incredibly high, with spinach especially being intensely sweet and a snap to sell. But growth rates under the system I detail here are too low for predictably good repeat harvests. I would plant a lot more were we in zone 8, where winters are really gentle. I’ve also had good harvests throughout winter on sites where I applied a thick layer of leaf mulch around all the plants. I would consider this again were our winter system intensive, rather than extensive, and if our farm were not so blowy that fallen tree leaves always disappear within two days. Gone with the wind takes on new meaning if you never have to rake the autumn leaves, and if field-installed Remay always tries to be reborn as a tattered kite rather than remain a crop-protection tool. A final hurdle with the chenopodes is that they draw deer like politicians draw lobbyists. Deer will hurdle fences to get to chard, and feeding those pests can be really expensive.

The onion family do well for us in some winters. Most reliably performing have been the perennial scallion types, with good harvests typically in November, March, and April. We are not very talented at growing leeks, regular bulbing onions, or garlics, so if you do these well I urge you to try this whole spectrum in the cold months.

The carrot family, the Apiaceae, does amazingly well in our winters. Parsnips were covered at length in the aforementioned book by Henderson, and here they make it through even the roughest winters to leaf out in March or April. I am ignorant of carrot performance in our winters, as winter weeding is reserved for high-value ornamentals and for the greenhouses. Carrots require more care than we want to give. Parsley, chervil, and dill often tolerate frosts and freezes down to about 28° F, with the heirloom strains performing better than the hybrids. But deeper winter freezes usually kill the lot. Better by far among the herbs of this family is cilantro, which seems to hunker down close to the ground and wait for the first breath of spring. A short-lived February thaw sees fast leaf development and marginally profitable harvesting, whereas March and April give great yields of high-quality cilantro. In mild winters overall survival approaches 100%; in severe ones we get about 65% mortality.

The final group to consider for unprotected winter cropping are the Asteraceae, the foremost being lettuces, chicories, radicchios, and dandelions. We grow an awful lot of lettuces but have had to adapt planting schedules to frequently hot Aprils. Our outside fall lettuce crops and greenhouse winter-long lettuce crops are much more profitable and reliable than the spring-sown batch. Autumn field lettuces in zone 7 can be outstandingly flavored, with 100% survival through the hard frosts and light freezes of November and early December. Then comes real winter. January usually sees full mortality of nearly all genelines of lettuces, with survival of about 0.2% of the hardiest cultivars. Useful for a breeding program, that, but not for most production farmers. When we grew near Raleigh, NC (zone 7b), well-managed lettuces easily had 80-100% survival through most winters. So we typically harvest field lettuces intensively, ahead of the looming deep freeze. Escaroles and endives do much better over winter here, especially the smooth-leaf types. They often perform almost as well as our brassicas. An experimental planting I did of six cultivars of heirloom radicchios was likewise encouraging, with 100% winter survival and only minor burning of leaf margins. But the real professional in the Aster family for overwintering is likely the dandelion. I am no fan of the bitterness of escarole or radicchio, having been fed way too many braised dandelion greens – in June – as a child. But the first tentative regrowth of dandelion in early spring is sweet, delicate, and wonderful. Were our farm in an area with higher demand for dandelion, escarole, and radicchio, we’d overwinter acres of these.

Greenhouse crops
Lettuces reign in our greenhouses, occupying 60-70% of planted space from September until March. Tender and fast growth is what the lettuces offer, and these are nearly always blended with the much higher quality baby field leaves to produce a truly elite mesclun. We also plant arugula, spinach, and two Asian mustards in 20% of prized greenhouse space to be able to keep our customers supplied with mesclun when the fields are locked in deep freeze. This purely greenhouse mix is better than the shipped-in competition, yes, but it lacks the sweetness and complexity of the field-plus-greenhouse blend. About 5% of greenhouse space is planted to cilantro, chervil, parsley, and dill, as a source of diversity for our CSA customers when the outside cold is unbearable. We let frost and even light freezes occur in the greenhouses to improve flavors, and have found most cultivars tolerate this quite well. By early February, though, we heat the greenhouses much more in order to keep healthy our newly-germinating transplants for the upcoming summer season. The lettuces really take off at that point.

Seed sourcing
Let’s be really clear here. Winter cropping in any zones colder than 8 is risky. Seed quality and genetic potential become increasingly vital as the sowing window shrinks with summer crops still in the field but with winter crops queuing up for planting. The big crunch for our current site is September 1 through October 7, and this means that slowly germinating purchased seed may well grow plants that are too small to stand even a mild freeze. I’ll cover planting in more detail in the next GFM.

So we need good or very good seed, and we need the strains for outside to have at least some – and ideally a stacked deck – of the genes for winter hardiness. Just as all strains of Brandywine tomato are not created equal, so all strains of curly kale aren’t at all the same in the arena of freeze-toleance. Part of our farm’s winter cropping system is recurrent selection of and seed saving from the winter survivors, but we still choose to buy some seed every year. I do not believe that freeze tolerance is a primary or even secondary goal of most U.S. seed companies. Instead, I suspect that the NEW!! IMPROVED!! GOLLY GEE WHAT A LIFE-SAVING HYBRID!! approach that dominates even the commercial seed trade has diluted or outright lost much of the cold hardiness for which nature and farmers selected over millennia. Rereading Peter Henderson’s work, it seems he may have had more trustworthy hardy cultivars to choose from a century ago, before the onset of utter farmer dependence on seed companies and the global shipping of produce all winter.
There is at least one positive exception for sourcing cold-hardy seed. Wyatt-Quarles Seeds (Garner, NC; 919- 772-4243; wholesale only) has consistently supplied our operation with excellent seed. And their brassica and even lettuce cultivars are not glitzy, not over-hyped, and absolutely come to the winter farmer with more built-in potential than any of the competition. In descending order of apparent genetic loading for freeze tolerance, we also use Fedco, Turtle Tree, High Mowing, Seed Savers Exchange, Johnny’s, and Shumway. The first four companies should also be commended for trying to grow as much of their seed as locally as possible, a huge step in the right direction for winter hardiness. This year, our farm is also selling limited quantities of our own cold –bred genelines for other farmers and seed companies to reproduce (call 301- 866-1412 for an informational packet). But for you right now, for plenty of off-the-shelf affordable seed that may well give you cold-season harvesting, Wyatt-Quarles is the company to call first. I propose here the counter-intuitive idea that some southern-tier seed companies may well be a better reservoir for cold hardiness than most northern companies. The northern growers seem to mostly assume (often correctly) that nothing can make it through winter. In contrast, a seed supplier in the Carolinas who sold collards that died at the first freeze would rapidly lose both face and customers. And we farmers can be a gossipy lot.

This covers about half of our winter cropping system. In the next GFM I will supply the rest of the management and sales details. Early September is planting time, so if cold-season farming at all appeals, you might want to consider crops and buy some seed soon.

Brett Grohsgal co-owns Even’ Star Organic Farm with his wife, Dr. Christine Bergmark, in southern Maryland.