Practicing Eliot Coleman s Winter Harvest System in Black Forest by Emmy McAllister, Copyright 2015. All rights reserved. http://www.amazon.com/the-winter-harvest-handbook- Greenhouses/dp/1603580816 Retail price, $29.95. Amazon price, $22.00.
Here in Black Forest, our weather has become more and more unpredictable. Many of us did not get our cool season crops in until much later this spring. Some of us even had to wait until mid-june! If this kind of weather pattern continues, (and even if it doesn t), we might want to seriously consider adopting some of the growing practices of world-renown organic market gardener, Eliot Coleman. Eliot has perfected some simple, inexpensive ways of growing vegetables so that he can harvest some of them all winter long and the rest of them very, very early in the spring, long before our spring-sown or spring planted cool weather crops ever mature here! We can enjoy harvesting our vegetables at the same times of the year as Eliot, because winter conditions here are even less challenging than his in Harborside, Maine, and he wrote all the directions and details for us in The Winter Harvest Handbook, which was published in 2009. Larry Rutherford has already proven that the method worked in his Black Forest garden last winter and this spring, so I encourage everyone to stumble forward and experiment! If your first sowing doesn t succeed sow, sow again! Eliot s winter harvest system is sun-driven. It requires no heat source except the sun! Eliot s Four Season Farm is at 44 degrees north latitude. We are at 39 degrees north latitude, five degrees latitude further south. This means that we get more hours of sunlight here in the winter than he does. And, incredibly, in spite of the fact that his farm is at sea level and we are at high altitude, our average winter temperatures are warmer than his! There are three components to Eliot s winter harvest system: 1) Vegetable varieties that are extremely cold-hardy. 2) Succession planting to provide a continual harvest, and 3) Protecting the plants under cover while they are growing. Surprisingly, there are many winter-grown vegetables that need only the minimal protection of an unheated Cold House or a Quick Hoop. When all three of these components are used together, there is great synergy! Here is the link to a two-hour presentation on the winter harvest system given by Eliot in 2012. The clip from this video that Paul and I showed at the June 14, 2015 meeting ran from about the 9 minute mark to about the 28 minute mark.
Eliot Coleman presents The Winter Harvest Handbook - YouTube This is our back yard version of Eliot s large, commercial Cold House. The sides of the outer covering slide up and down and the ends are quickly removable. In our backyard gardens, we may want reserve certain areas or raised beds exclusively for winter harvest use because of the long periods of time that the winter harvest crops occupy the soil. Cold Houses are situated on an east-west axis. They need only a single layer of UV-resistant plastic. The secret to withstanding temperatures of down to 20 below zero is a second layer of protection made of row cover inside the plastic layer so that the soil itself becomes the heat-storage medium. (You will find the names of the products Eliot uses, where to get them and what they cost at the end of this article.)
The rows inside Eliot s Cold Houses are 30 inches wide. The row covers are supported by flat-topped wire wickets that hold the row covers 12 inches above the soil. The double coverage not only retains the sun s heat, but also increases the relative humidity underneath, which offers additional protection against freezing. The double layer moves the plants 1000 miles to the south. Coleman says, We are not extending the growing season. We are extending the harvest season. They plant in August, September and October. Many of the plants are hibernating in the winter, not growing. Plants are harvested young because younger plants are usually hardier than older ones. The outer covering: Anti-drip coatings cause condensed moisture to form a thin film instead of droplets. They let in more light and the thin moisture film acts to reflect back the heat waves radiating from the soil at night, thus helping to keep the air inside the cold house warmer. They make the wickets from lengths of #9 wire. Each leg is 23 inches long, and holds the row cover a foot above the soil. They pull it tight and clip it to the end wires with clothespins, (see below). The objective is to keep the cover from touching the plants.
Making two visits to one of our cold houses one at dawn after a below zero night, and the other a few hours later provide a striking introduction to the winter harvest. During the dawn visit all the crops are frozen solid.yet a few hours later, after the sun, even on a cloudy day, has warmed the cold houses above freezing, the second visit presents a miraculous contrast rows of vigorous, healthy leaves. No scientific data can offer as much information or inspiration as those two visits to the cold house! Eliot Coleman Too warm is more damaging to winter harvest crops than too cold. So they wait to put the inner row covers on until just before the weather is cold enough to freeze the inside of the Cold House, and by mid-march at the latest, they begin folding back the row covers on sunny days to prevent overheating of the crops underneath. They do not irrigate during the winter months. For growers in Zones 3 to 6, like us, Eliot recommends growing only the most cold-hardy crops in the coldest months of winter, (mache, leeks, claytonia and Asian greens), and experimenting with another layer of protection, such as using cold frames inside the cold houses, which can be covered with old rugs or mats for extra protection. Some of us are in Zone 6 around here, and others in Zones 4 or 5. We might not need cold frames, except perhaps for the baby potatoes and the cabbages.
Cut and come again winter crops like spinach, chard, claytonia, and tatsoi continue productive regrowth after harvest as long as they have well established root systems. The time from planting to maturity triples in a cold house. Limited sunlight and cold temperatures cause plant growth to slow way down during the winter months, so knowing the best sowing dates for each vegetable in the fall and winter is much more important than when sowing seeds in the spring, when the time from sowing to maturity is much shorter.
This graph shows the effects of reduced sunlight and cold temperatures on a crop that would normally take 40 days to mature. The same crop required 120 days to mature in the Cold House. You can use this graph to calculate how many days in advance to plant in order to harvest at any particular date on the horizontal axis. For example, to plan a March 15 harvest, find the point on the graph where March 15 lies on the coldhouse curve. From there, trace down to a number on the horizontal axis. That number, which is 118, means that you would want to plant 118 days before March 15, (November 17), for a March 15 harvest. The formula for this calculation is based on the ratio between the day length at our latitude and his. The National Weather Service web site offer instant day length calculations for any location: www.srrb.noaa.gov/highlights/sunrise/sunrise.html Since we are south of Eliot s garden, at around the 39 th parallel, and Eliot s garden is approximately at the 45 th parallel, we get more hours of sunlight each day in the winter than he does, and we could decrease our expected number of days from planting to harvest accordingly. But 39 divided by 45 =.8666, or only about one day. So we could use Eliot s chart just the way it is, without even subtracting a day. Winter crops grown in the Cold Houses, where there is easy access to them all winter long for harvest: Mache: Vit Miner s lettuce (claytonia) Beet Roots: Touchstone Gold, Red Ace and Merlin Beet Leaves: Bull s Blood and Red Ace
Spinach: Space and Palco hybrid. Overwintered spinach has become Eliot s major winter green crop. It produces new leaves all winter, unlike kale, for example. Endive: Bianca Riccia Lettuce: Oak leaf red lettuce, Rouge d hiver, Red Salad Bowl, Tango, Rex Arugula: Sylvetta and Astro Swiss Chard: Fordhook Giant and Ruby Red; narrow stem Swiss chard, (butter chard), harvested when the leaves are the size of a man s hand. Carrots: Mokum, (candy carrots), Napoli and Nelson Asian greens, (the hardiest of all winter greens): Komatsuna, Tokyo Bekana, Tatsoi, Pak Choi, Mei Qing Choi; Mizuna Leeks: Tadorna, (don t even need the second covering) Scallions: White Spear Onions: Short day onion varieties plus Walla Walla and Olympic, which are overwintering varieties Turnips and turnip greens: Hakurei hybrid variety, small and sweet Potatoes: Rose Gold baby potatoes Sprout indoors in mid-to late February at 70 degrees for a week to break apical dominance and increase the number of sprouts. Plant around St. Patrick s Day, March 17, in a Cold House. Plant two rows down a 30 wide bed. May need an extra cover at night if temperatures threaten to freeze under the row cover. For that reason, consider growing the potatoes in a cold frame inside the cold house instead of under row cover inside of the cold house, so the roof of the frame can support the extra covers. It takes only two months for baby potatoes to reach harvestable, golf-ball size. Harvest in mid to late May.
Quick Hoops for protecting low-growing, overwintered crops: Crops that are actually harvested during the winter, like some varieties of leeks, require the easy access provided in a Cold House. But low-growing, overwintered crops, grown for extra early spring harvest, like overwintering onions, scallions, spinach and lettuce and many others listed later in this article, could be protected by low, inexpensive, temporary structures called Quick Hoops. Eliot plants overwintering onions during the last week of August and places the hoops and row cover over them in mid-october. The advantage of overwintered onion varieties is that the bulbs mature the end of June, providing a spring harvest as well as the traditional fall harvest. The supports of the Quick Hoops are 10 foot lengths of half inch electrical conduit, either plastic or metal. Bowed into a half circle, they nicely cover two 30 inch beds side by side with a path between them.
Eliot inserts each end of the conduit about ten inches into the soil on either side of the two beds, forming a hoop about 30 inches high at the midpoint. Plastic conduit can be bent as you put each support in place; metal conduit must be prebent to the ideal shape with a tubing bender. He places one hoop every five feet along the length of the beds. The hoops are them covered initially with ten foot wide spun bonded row cover held down by sand bags placed every five feet along the edge. Later, when real winter weather threatens, he adds a sheet of ten foot wide clear plastic over the row cover to make the quick hoop tunnels more snow proof. (See the companion article on our website describing the process in more detail. It is called, Coleman s Quick Hoops (Double-Covered Low Tunnels -- The 2007 Version ). To stiffen the structure against wind and snow load, it s important to tighten the plastic. (In the video we showed at the June 14, 2015 meeting, Eliot describes how they now use the A frame shape instead of the bow shape because it sheds snow much better and therefore has much less chance of collapsing under the weight; but the low, bow-shaped tunnels would probably work best for our climate due to strong winter winds and much less snow.) When spring arrives, Eliot starts ventilating Quick Hoops on sunny days. He removes a few sand bags along the southern edge and inserts a notched prop to
hold up the edges of the plastic and fabric. Once outdoor temperatures have moderated to the point where the fabric alone is protection enough, he removes the plastic layer and stores it until next winter. Here in Black Forest, we might opt to just fold them down and keep them ready to pull up and over to protect our plants against hail. Quick hoops can be disassembled and moved to cover other crops later in the spring. New Opportunities for Northern Growers Because of the low cost of cold houses and Quick Hoops, northern growers now have the opportunity to explore late-fall planting of spring crops, a growing strategy that growers in warmer climates, like the Puget Sound area where I came from, routinely use. To take advantage of this opportunity, we need to know: 1) How early we can plant certain fall-seeded crops to have them mature earlier in the spring without triggering them to go to seed rapidly as the weather warms up. In other words, we need to know the initial planting date for each crop and the planting dates we would choose for each
successive planting of that crop to get continuous harvests. We would use Eliot s graph to help us figure this out. Since the sowing and planting date charts for 6000 feet elevation and 7400 feet elevation shown on our website have been unreliable this year, it would probably be best to decide on our sowing dates by using the germination temperature tables on our website instead. In other words, taking the soil s temperature at dawn, before it has had time to warm up to determine whether the soil is warm enough to germinate that crop s seed. 2) At what size or stage of growth each kind of young seedling is the hardiest, for surviving the cold winter weather. (Eliot gives us this information in his book. I hope to compile a chart for this information. 3) What crops can be sown just before the ground freezes, to overwinter as seeds and germinate extra early in the spring, like our winter wheat did this year. 4) What crop varieties can be overwintered -- that is, started in the late summer or early fall to hibernate through the winter, and then start growing again early in the spring to yield a very early spring harvest. (See a list of overwintering varieties below. This list is not all inclusive. The Fall and Winter Territorial Seed Co. catalog offers many of these varieties because they overwinter well in the Pacific Northwest without any winter protection at all in many cases.)
Varieties that could overwinter well in Quick Hoops or Cold Houses: Onions: Walla Walla Sweet Onions, 125 days OP. TS; Olympic; Gatekeeper Onions, 150 days, F1 hybrid. TS; Stockton Early Reds; Sweet Winter Onions; Red Marble Onions, 93-105 days, OP. TS; Scallions: Winter White Overwintering Bunching Onions 120 days OP. TS; White Lisbon Overwintering Salad Onions, 60-120 days, OP. TS; Welch Onions; White Spear Scallions; Kujo Multistalk; Shimonita; Leeks: Giant Musselburgh produces a thick, white, tender stalk two or three inches in diameter. You can succession plant in the cold house for baby leeks through the next summer, or let them overwinter under Quick Hoops until they mature in 105 days. Eliot uses the Todorna variety. They don t require a row cover in the cold house. Other winter varieties include Alaska from Stokes; Giant Winter; Carentan, (extremely hardy), and Winta TS. Garlic: Many hard neck varieties. Cauliflower: Overwintering to Spring Harvest Blend from TS. Open pollinated.
Broccoli: Purple Sprouting; Tyfon: A sweet-tasting sprouting broccoli-type tall plant. Most biomass per square foot of garden space. People and chickens love eating this crop! Cabbage: Sow in September and overwinter in cold frames in the Cold Houses. Remove the frames when the cabbages get too tall, OR grow under Quick Hoops, which are about 30 tall at their peaks. Jersey Wakefield, April Monarch, First Early Market, Filderkraut, Berra Tronchuda. Carrots: Merida Overwintering F1 Hybrid, 240 days for growing under the Quick Hoops TS. Mokum, (Candy Carrots), and Napoli, the varieties that Eliot grows in his Cold Houses, are not overwintering in the true sense of the word, because they mature in the late fall instead of early spring. Once they are mature, they are covered with straw and then dug as needed all winter. Spinach: Palco F1 Hybrid can be grown under a Quick Hoop or in a cold house for easier access. 38 days. Multiple cuttings. Great variety for baby spinach. Parsley Root: Halblange 120 days. TS OP. Lettuce: Arctic King Butterhead OP 150 days. TS Tools and supplies from Johnny s Selected Seeds in Winslow, Maine, www.johnnyseeds.com 1-877-564-6697 Catalog page numbers are listed below.
Clear plastic outer covering: Tufflite 4 mil Nursery Clear Greenhouse Film. UV resistant and ultra clear. Extremely durable. 10 feet X 100 feet, $82.95. A great candidate for a group purchase! Page 194. Row cover: Quick Hoop initial covering: Agribon AG-19 Floating Row Cover for frost protection and overwintering. Light transmission, 85%. 10 X 50 feet, $31.15. Cut in half to provide a 5 foot Inner covering over wickets for Cold House crops in 30 beds. Page 200. Clamps for securing plastic and row cover to conduit hoops: Snap Clamps for 1/2 PVC pipe. Pkg. of 10 for $5.45 Page 194. Wiggle Wire Connection System for connecting plastic, row cover or shade cloth to framework. Four foot section of Wiggle Wire, $1.75. Eight foot channel section, $9.25. Page 196. Coiled #9 Galvanized Wire for wickets inside of Cold Houses: 60 $29.95. Page 201. Cuts easily with a bolt cutter. Locally sourced materials: Electrical conduit for Quick Hoop frames: either ½ PVC or metal pipe
Wire for wire wickets that support the Agribon row covers inside the cold houses: Either 76 long straight lengths of # 9 wire made by Ken-Bar, Inc. and carried by most greenhouse dealers. To locate a local dealer, contact Ken-Bar, Inc., Peabody, MA 800-336-8882 or www.ken-bar.com Sources for specialty materials: 6 foot wide metal row cover hoop benders: Lost Creek Greenhouse Systems, Mineola, TX 903-569-8541 www.lostcreek.net