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Heating the Greenhouse (continued)

We’ve got a small solar system on one of our chicken tractors that can be switched over to control the thermostat on the heater and the exhaust fan if we lose electricity long-term in the greenhouse. If we need to, we can move the woodstove back in, but for now this system works well. No matter what kind of heating system you choose, having a backup plan makes you sleep easier at night. At minimum have a kerosene heater and a few cans of fuel on hand that you can move into the greenhouse for a night or two if your main heat or electricity goes out. It will save a greenhouse full of plants and a season’s worth of food.

Temporary Greenhouses and Tunnels

Instead of a permanent wooden or metal-framed greenhouse, you can use a less expensive, temporary greenhouse design made from PVC. However, I wouldn’t recommend it, because they will only last a year or two and have no snow load capacity. The PVC will get brittle in the sun, and a good wind or a small snow will break them down. This will most likely happen when they are full of plants and/or there is a blizzard. Trust me, I’ve constructed several over the years, and the end result is always the same. Unless you absolutely can’t afford anything else, just save yourself the trouble and put up a more permanent structure. If you don’t want to frame up a wooden greenhouse, I would suggest getting a greenhouse bow bender from Johnny Seeds . These are less than one hundred dollars and you can bend the bows to construct several sizes and styles of greenhouses from readily available, and affordable, chain link fence piping.

They also sell low tunnel benders, which make short tunnels about waist high from ½-inch or ¾-inch electrical conduit. These are pretty much extended cold frames, which serve the same purpose. Low tunnels have become a mainstay in our production, as they are affordable and very quick and easy to put up and take down. We cover them with plastic early to get a jump on the season in the spring, and then use a woven floating row cover when it warms up. The clear plastic can heat up fast and kill whatever is inside without proper venting. So, if you aren’t going to be around to constantly monitor your low tunnels, then just stick to the woven covers, which will give you less heating but at the same time won’t overheat. The added benefit to these covers is the protection from insects.

Most of our early mustard and greens crops go under these woven covers to exclude flea beetles, which if left uncovered will be decimated without a lot of pesticide sprays. Use of these covers allows us to grow these greens perfectly without chemical sprays, which is worth their cost alone.

You can also use the lighter weight fabric without a frame, just letting it float over crop, thus it is sometimes called a “floating row cover”. In both uses the edges have to be weighed down to keep them in place and to prevent insects from getting underneath. We’ve found that using sandbags to weigh down the edges is the best option, as they don’t tear holes in the fabric. Just making use of this material alone will increase the quality and yield of your produce exponentially. This is one of the items that you should buy and lay up for a rainy day while it is still readily available. If protected from the sun it will keep indefinitely and is one of our most valuable resources on the farm.

A high-tunnel is essentially an unheated greenhouse in which you grow everything in the ground. Even a single layer of plastic allows you to plant about three weeks earlier in the spring and lets you extend the season at the end a month or more. Those extra weeks make a big difference in the availability and amount of food you can produce in a year. Late summer plantings of cold-season crops like collards, kale, chard, spinach, lettuce, and carrots can be made in the high-tunnel and harvested throughout the winter. You can put low-tunnels within high tunnels for the coldest climates. The plants don’t really grow in the winter, but rather if they are fully mature in the fall they are held in a living dormant state in what is essentially a giant walk-in refrigerator.

Most high tunnels have roll up sides or end-doors that you open up manually for ventilation. If you aren’t around during the day, you’ll need an automatic venting system, as a high tunnel can overheat and kill your plants, although not as fast as a low-tunnel. All of these structures need to be covered with special greenhouse film that is UV treated, or it won’t last. Treated 6-mil film is guaranteed for about four years, although I’ve left it on a lot longer. It just becomes opaque over time and lets less light pass through.

I’ll give an example of how your greenhouse and your high-tunnel allow you to exponentially lengthen your growing season and your potential food production. As I mentioned before, we are in USDA zone 6 and east of the Mississippi. If you are located in colder Zone 5 or warmer Zone 7, you can tweak the dates I use a bit, but there won’t be a huge difference, and most of the country’s population will find themselves in one of these three zones.

Let’s take tomatoes for an example, as everyone likes to grow them. If you want to direct seed tomatoes directly in the ground, you can do that around the end of April or the first of May when the soil is warm enough so that the seed germinates directly in the ground. From that direct seeding you will have a ripe tomato from most common 70-day varieties around four months later, or in late August/early September. The first frost comes in October, so you’ve got about six weeks of ripe tomatoes. You’d better grow a bunch at one time and have the capacity to preserve them if you want tomatoes to use year-round.

Now here is an alternative that we use to extend our season. Our first tomatoes get seeded on February 1st in the greenhouse. That gives us large, healthy, eight-week old transplants the first of April that go into the high tunnel. We get some frosts in April, but the unheated high tunnel is enough protection in most years; if it gets super cold, we can cover the plants inside with a woven frost blanket, or even move in a portable kerosene heater for a night or two, which has always been enough, since we’ve never lost our early crop to frost. We use a super-early tomato for our first crop. (We like Stupice or Polbig). By doing this we can have ripe tomatoes by the middle of May.

We continue to seed and plant a succession of field and high-tunnel tomatoes throughout the season with the last being seeded when the first tomatoes are ripening. The very latest varieties are transplanted into 15-gallon pots and moved into the now empty greenhouse. They’ll grow just fine there with a minimum and very efficient use of supplemental heat. If the weather gets really cold and it doesn’t make financial sense to keep burning propane, then we can harvest the rest of the tomatoes and move them into the basement. This is normally right around Christmas.

By using storage varieties (Burpee’s Longkeeper, “Reverand Morrow’s Longkeeper”, Giraffe, et cetera) that have a long shelf-life, you can continue to have edible fresh tomatoes for another six weeks or so, which gets you through January and into February if you are lucky. So then, you’ve got three months of canned/dehydrated tomatoes that will get you to your first ripe tomatoes in May. Having fresh tomatoes nine months of the year in our area is just one example of the worth of the investment in season extension.

For most, these structures will end up being multi-use. We often use our high tunnels in the fall for temporary animal housing. They clean up the weeds and fertilize the soil with their manure, which is tilled in and decomposed before we replant. We also use ours for drying crops in mid-summer when it’s too hot to grow anything inside. We use the better-insulated greenhouse for overwintering plants that need a bit of help, like our potted figs and semi-hardy herbs, like rosemary. Outside they might be winter killed, but in the depths of winter our greenhouse is mild even without heat. A greenhouse kept heated above freezing gives you access to those favorite tropical plants of ours, like tea, olive, citrus, or banana that may not be possible in your part of the country outside a heated environment.

I was blessed to grow up on a farm and later was fortunate to be able to receive an advanced degree in Agriculture. For the last 15 years my wife and I have been running a small diversified farm where we produce vegetables, fruit, and animal products for local markets and a C.S.A. (Community Supported Agriculture). During this time we’ve spent several years in several countries doing agricultural mission work, seeing how the rest of the world feeds itself, and doing our part to assist them with that.

Over time we’ve worked hard to turn our own 30-acre farm into a self-sufficient property. My goal has been to see our farm as one that could feed my family and other families far into the future if “the front gate gets shut and locked.” As SurvivalBlog readers are well aware, this seems to be more of a possibility with every passing day. The discussion on growing your own food often arises, and a recurring theme is the advice that you aren’t just going to open a pack of survival seeds and feed your family. I couldn’t agree more, but I often feel like readers get brow-beaten with that advice and can leave the discussion a bit overwhelmed and in the end do nothing to advance their food security.

Growing enough food to feed your family for an extended period of time is a daunting task, but let me assure you that it is doable with a plan, a little land, and the willingness to try. We have to be successful every year in order to stay in business, and that has naturally led us into growing techniques that work. With this article I want to share with you a few key elements of these techniques that I hope will be a big help in your journey towards food security.

Element Number One: The Importance of Timing and Food Storage

Step number one for growing enough food to survive is food storage. Now I know that this seems contradictory, since we are talking about growing food. Why would we store a bunch of food if we are planning on growing it ourselves? The answer is timing. Unless you never buy anything from the grocery store and already grow all your own food, year-round, most people would need to ramp up production tremendously in order to provide all of the food that they need.

Nobody knows when the tractor trailers will stop rolling and the grocery shelves will be empty. It could be any time of the year. The absolute worst time of the year for this to happen would be at the end of summer or the beginning of fall when warm season crops are a distant memory and it may be even too late to start any cool season/winter crops, which are normally started in August/September in our Zone 6. Starting in October, you would have a long winter and at least six months before the earliest spring crops could be harvested, and even longer for the high-calorie crops like potatoes, corn, and other carbohydrate-rich grains. So, even if you are planning on growing enough to feed yourself, six months of food storage is a minimum. A year’s worth is even better, especially for inexperienced growers. You’ll definitely need a little food insurance, as your first year’s crops are probably not going to meet your expectations.

If you are going to be eating year-round from food you produce yourself, it makes sense that you need to be growing just about year round. There is no need to take the extra expense and work to preserve all your food when you can eat most of it fresh. This is entirely possible in most zones, with good planning and the willingness to eat a wider variety of crops than corn, beans, and tomatoes.

The key here is a good plan and a succession of crops that are planted and harvested at the right time. The easiest way I’ve found to do this is to buy a cheap monthly planner and to write all my seeding, transplanting, and harvest dates down. Make notes on what varieties you use, what works and what doesn’t. Start with a planting calendar from your local extension agent if you need a place to begin. The point is that every year you tweak your planting schedule on what works best, and after a season or two you’ll be way ahead of the game and planning will get easier with every passing year.

The bulk of our produce is grown from April to October, but we have things growing and eatable, pretty much year round. We do this with some basic season extension techniques, the main one being the use of a greenhouse and unheated high tunnels.

Element Number Two: Season Extension

A key element to growing success is how long it takes you to go from seed to harvest and how much of the year you are able to produce food. The normal three or four month growing season most people enjoy is not enough to produce the food you’ll need for the entire year, especially if you are limited in growing space. For that reason you are going to have to use season extension techniques with a minimum of a small heated greenhouse and a bigger unheated high-tunnel.

The one technique that we use that I consider the most valuable in extending our season and resulting in successful crops is producing our own transplants. Using a transplant rather than direct seeding crops automatically allows you to start the growing season weeks ahead of time. If we can start it in the greenhouse, we do. The only crops that don’t begin as transplants are the large seeded crops, like corn and beans, as well as some of the root crops like carrots. That said, even corn and beans can be transplanted, but they can only stay in pots for about two weeks before they need to be set out, so you aren’t gaining that much. If you have the ability and means to start your own plants from seeds, you are greatly broadening your horizons into the best varieties for survival gardens that you will never see for sale as a transplant in your local nursery or garden center.

Another advantage of producing your own transplants is the fact that you can provide optimum germination conditions for your seeds, which means you need less of them. You also give the plants several weeks head-start free from weed-competition, which is the bane of direct seeded crops. If the weather is not conducive to plant growth you can hold the plants a little longer in a protected environment before planting them out. A trick I use is to use a larger volume container for the first transplants I produce. That way they have plenty of growing space if I need to hold them a week or two later to wait for the weather. The later transplants that go from seed to field in just a few weeks get smaller containers that take less soil, as there won’t likely be a need to hold them longer in the greenhouse.

It doesn’t have to be big, but you do have to have a place to produce transplants. We are a commercial farm, but our greenhouse is only about 14 by 33 feet, and for several years we made due with one half that size. For a small family, an eight by twelve foot greenhouse would be a good start and would be doable in most anyone’s backyard. Of course, go as big as you can afford or have space for, as you’ll find a greenhouse is a useful structure that can be used year around. Our current greenhouse has insulated north and west walls and is a wood frame covered by double-walled poly-panels.

On the north wall we have a bank of 55-gallon water barrels that act as a heat sink, as well as a base for our plant benches. This water bank is made from food-grade poly barrels that are locally available for about eight dollars each. Filled with potable water, this is also an instant water storage system of nearly 1000 gallons of water. This design is very efficient, and we can heat it with a small propane heater. We’ve got a mid-sized storage tank that holds about two years worth of propane at our current usage.

Heating the Greenhouse

I tried a wood stove to heat the greenhouse at one point, but it just doesn’t make sense unless you are living in the greenhouse and can constantly monitor the temperature. An external wood burning boiler on a thermostat would be great, but it doesn’t make economic sense to use a costly unit like that to heat a small greenhouse. It’s better to spend money on improved insulation and be able to use a smaller heater.