The changing seasons each offer their own unique sets of challenges as well as potential benefits.  Moving into the fall growing season, the daylight hours continue to reduce in length and the temperature begins to cool which, in turn, lowers the temperature of the soil.  While this may slow down the growth of crops in the field, new innovations in small to mid scale agriculture technology provide ample opportunity to continue the harvest well into the winter season and, in some of the warmer regions, right on through it. The low light and temps might be presenting plants with less environmental support, but the good news is, these conditions are likely reducing the weed pressure and eliminating the presence of summer pests.  This lack of competition mixed with the slower growth rate of crops makes for a less hectic season which can be sweet relief after a long summer of heavy harvests, weeding, and crop maintenance. While the methodology of each season extension innovation is dependent on region, there are some universal tools that can help keep the harvest rolling and income streams alive.  Below is a compilation of some of the most widely utilized tools and methods.
Site Selection
When it comes to season extension, the goal is to protect crops from the damaging effects of the cooler climate which can be caused by wind, precipitation, frost, low light, and the cold water and soil temperatures.  While there are many cultural practices and tools that can help protect crops overwintering or growing later into the fall season, an important first step is to consider the space you have allocated for production.  Sometimes there isn't any wiggle room when it comes to where the garden must be placed and you need to work with what you have, and other times you can choose the location where the crops will have the greatest chance for success. When choosing a site for fall/winter production, choosing a location with maximum sun exposure will help plants cope with the low light conditions.  A location that has plant or hillside buffer surrounding it can help insulate the crops from difficult winter weather.  Watching where snow drifts collect and keeping plants away from places that tend towards excess water accumulation allows plants to function at more optimal levels.  Observation is an important tool in any productive system but is especially important when attempting to carry harvests later into the season when conditions are less favorable for healthy growth.
High Tunnels/Hoophouses
Whether you call it a Hoophouse or a High Tunnel, these elegant structures have been adapted for use by everyone from large scale tomato producers to the self sufficient homesteader.  The slender frames and plastic walls make for high light exposure and protect plants and soil from the environmental impacts of heavy rains, hail, snow, and damaging winds.  The plastic concentrates the impacts of the sun, warming the soil and the plants even when the weather outside is cold.  Plants grow lush and beautiful within these comfortable growing conditions, especially when the soil is properly amended for production. High Tunnels are excellent season extension agents as they create an entirely different climate from the cooling temperatures of the fall and winter growing season.  These structures can be heated for winter use utilizing propane, a wood stove, or pellet stove and unheated tunnels can still reap all of the benefits of the extra warmth and protection when floating row cover is used over the plants as an additional layer of frost protection.
Low Tunnels/Caterpillar Tunnels/Quick Hoops
Low Tunnels, Caterpillar Tunnels, and Quick Hoops are all of the names given to growing tunnels made of typically pvc or metal hoops that are covered in a layer of plastic or floating row cover.  These structures come in various sizes from tall enough to walk through to just tall enough to cover a bed of crops.  They offer the season extension benefits that are attributed to High Tunnels without the cost.  Because they are generally lower to the ground and have less parts, they have less of a risk of getting damaged during storms.  The structures are simple, which makes them easy to move from field to field and can be incorporated into a crop rotation. Choosing the height of your low tunnel is associated with how much maintenance each crop requires.  For crops that are likely to overwinter with little maintenance, like carrots or onions, a very low tunnel suits best as it is cost effective and will be left alone throughout most of the winter season.  For crops that will be harvested or require more care throughout the cool growing season like broccoli, spinach, lettuce, peas, and others, a tunnel that can comfortably fit one to two people can help keep the system efficient.
Floating Row Cover
Floating row cover is a season extension tool that is an alternative to using plastic to cover hoops.  The light weight, breathable material is woven and allows moisture and sunlight to reach the crops below it.  Often used to deter pest pressure during the spring and summer, this material has many applications throughout the seasons in an organic growing system and comes in different "weights," from light to heavy, with the lightest being the most breathable and the heaviest offering the most hardiness to frost and cold.  The cover raises the interior temperature of the planted bed several degrees and can protect tender plants from transplant shock, frost, and even light accumulations of snow.  When serious cold weather threatens the well being of crops, a double layer of frost cover can get plants through a difficult nighttime low or snow storm. Floating row cover can also be laid directly on a bed without hoops when plants are germinating.  Sometimes this added weight and moisture barrier on the soil can help sprout more difficult crops to germinate like carrots.  Whether getting things started early or keeping things growing into the late season, floating row covers are one of the most versatile, user friendly innovations in season extension technology on the market today.
Cold Frames
Of all of the season extension structures, cold frames are definitely the leaders in DIY construction and design.  Often made of recycled glass windows, cold frames can be built out of many things and can be designed with the needs of the operation in mind.  Most commonly these season extension agents are lower to the ground and are most suitable for ground level crops like greens, roots, and herbs.  Taller cold frames can be made, as they can be tailored to the needs of any situation, but wooden sides on a tall frame can sometimes contribute to legginess in crops as they reach for the sun above. Cold frames can be seeded or transplanted directly into, or can house transplant trays waiting for warmer weather.  Cold frames are also great places to start seeds for bare root transplanted vegetables that will be moved from the cold frames into the field when the conditions are appropriate for field planting.
Plastic Mulch
Plastic mulch is used in many cases to suppress weed pressures in the field for plants that stay in the soil for extended periods of time.  Using plastic mulch is very common in tomato, pepper, and eggplant production and comes in varying sizes, colors and weights to meet the needs of the growing season and desired plant system.  A woven plastic like landscape fabric can be used multiple times while a black plastic film is often used for just one season.  Biodegradable plastic mulch has been developed to try and reduce the amount of plastic waste produced on the farm, though it is not currently approved by the NOP for Organic production. Black plastic is great for limiting weeds, but in season extension, it has an even more important role of warming up the soil.  The black color of the plastic attracts light which, in turn, warms up the top layers of the earth beneath it.  The warmed soil stimulates the activity of soil microorganisms that are key contributors to the nutrient cycle that stabilizes plants.  Black plastic partnered with quick hoops of floating row cover can create an environment that is significantly more temperate than the outside temperatures and can see plants through very cold conditions.  Using black plastic and plastic covered hoops will bring even more heat to the environment, but needs to be monitored as all of the plastic limits the air flow which can contribute to high humidity and overheating if not properly ventilated during warmer streaks of weather.
Windbreaks
As the leaves on the trees fall and the growing spaces of the farm or garden become more exposed, thinking about the movement of air through the property can help protect crops from the harshest changes in climate associated with fall and winter growing.  When thinking about where to grow fall and winter crops, choosing a place that is insulated by the protection of hillsides, forested land, or intentionally planted windbreaks can help guard plants from the damaging effects caused by exposure to constant wind.  Wind can pull moisture from plants and can increase the likelihood of cold damage on tender crops. Planting windbreaks where the wind most commonly surges through the property in winter is an effective strategy to buffer the growing space.  There are likely well adapted native plants in your region that can serve this purpose as well as a long list of productive perennial cultivars.  Windbreaks can also just be walls or fences that break up the force of the wind before it reaches the field.
Cultivar Selection
When it comes to making the most of the fall and winter growing seasons, it is important to choose plants and varieties that are adapted to survive in these cooler, low light conditions.  First, it is good to aim for crops that tolerate cooler climates.  There is a great diversity of greens such as asian and mustard greens, spinach, kale, lettuces, salad mixes, collards, and others that can withstand cooler temperatures when being supported with season extension technology.  Along with greens, many roots such as beets, carrots, parsnips, turnips, and radishes can also be successfully grown and overwintered in certain climes.  Broccoli, cauliflower, cabbage, and brussels sprouts are also great crops to extend into the fall season.  At High Mowing, we offer many cultivars that are specifically suited for cooler growing seasons and can provide for ample harvests even when the winter begins to set in. One of the easiest ways of extending the season of fresh harvested foods is to grow microgreens.  These gorgeous little shoots are tender, pack a flavor punch, and are full of valuable nutrients that become scarce in many places when the weather turns frigid.  They can be grown for the kitchen, the winter CSA, or for the farmers market and their capacity for extending the growing season is unlimited.