Choosing Your Growing Structure

Choosing Your Growing Structure
By Richard Bogdanowicz

We are now in late fall, approaching early winter and if you're like me and many other farmers/growers in this part of the world, you're ordering your seeds to start them for the ever-so-near growing season. To ensure the success of a growing season, many farmers, I included, have invested in outdoor plant-growing structures such as greenhouses, hoop houses, polytunnels, and geodesic domes. If you are someone looking to maybe switch your current growing structure for a different type, or a beginner looking to choose their first, or even someone just curious about the differences, advantages, and disadvantages of greenhouses, hoop houses, polytunnels, or geodesic domes, this article will hopefully enlighten you and help you come to a decision.

Greenhouses

Arguably the most famous and well-known type of growing structure-the greenhouse, is wonderful for out-of-season growing. Yes, I'm talking about fresh tomatoes in February! A greenhouse is typically a rectangular or square shaped building (some variations in shape are possible of course) made of either polyethylene or glass walls. A major disadvantage of a greenhouse, which is shared with the geodesic domes, is the cost. Choice in structure such as either polyethylene or glass walls, high tech or lo tech ventilation and heating, and other fine details determine the price which can be up to $20,000 (at $7.56 per square foot) or below.

Of course, there are ways to lower the price though. For one, building it yourself is going to save A LOT of money opposed to hiring a company to build it. Then, consider the exterior covering: Polyethylene or Glass. Polyethylene is the cheaper option and it's double layers makes it less expensive to heat than a glasshouse, BUT on the downside, the use of polyethylene leads to reduced light conditions in the winter and increased humidity in the summer. (As an added note, humidity equals fungus which equals dead plants.) Finally, when considering cost, it is in your best interest to make sure you know that you can more than earn back what you have invested through the profit made off of the crops grown in the greenhouse.

I think the obvious disadvantage here is the $$$ (for building and heating). Keeping that in mind, there are MANY advantages to using a greenhouse to more than counter the negative aspects. The biggest advantage here is that with a greenhouse, you can grow plants virtually year-round! Other advantages here include that they are relatively simple to assemble, they protect plants from the elements (wind, rain, hail) and soil-borne diseases, plants in a greenhouse generally have a higher yield, and there is great versatility/freedom in the growing techniques used within a greenhouse. Greenhouses can be placed on an exposed ground for in-ground soil culture or placed on a concrete slab or even over gravel! Then to add to this greenhouse conundrum, watering methods and planting methods change with each setting variation.

Polytunnels

If you are a grower looking for a structure to use for growing A LOT of produce, this is probably your best option (unless you live in a really windy area, but I will get to that later). A polytunnel is what it sounds like-a tunnel of polyethylene. Very similar to a hoop house, a polytunnel is a metal framed semi-circular tunnel that captures a lot of air space which has its advantages in that it stays warmer longer than a greenhouse. Variations on its structure can be made through using Bubble-Wrap insulation in the winter to ensure a frost-free winter, a source of heating, and the type of ventilation you decide to install.

Disadvantages are as plentiful as the advantages but it all depends on what you're looking for and your location. First of all, when I think of a long tunnel, the first thing that pops in my mind is "SPACE." Simply put, if you do not have the space, this will not work for you (a hoop house may make a better alternative if shorter). Also, it does not look too aesthetically appealing... it is a metal framed tube of plastic... BUT if looks are a concern of yours, consider a glass greenhouse or a geodesic dome. Location matters because wind will take a toll on your polytunnel. If you and a friend have ever stretched out a tarp facing the wind and had it ripped right from your hands, well that is the same effect strong wind has on a polytunnel. Long story short, it will rip itself from the ground and fly to who-knows-where. Lastly, a major disadvantage is that polyethylene is vulnerable and not easy to fix, in fact, you can use all the duct tape you want to fix that hole in your polytunnel, but that hole will eventually open back up and tear further.

To add some sunshine to the dark clouds over the disadvantages of polytunnels, there are plenty of advantages. The obvious ones here are that it extends the growing season and adds to the variation in crops to be planted within by adding more space. A huge plus is the cost, which is much cheaper and affordable than a greenhouse or geodesic dome. Crop rotation, if planting in the ground, is commonly known as essential to the prevention of plant disease and with a polytunnel, you can simply move it to a new area being that it is not as permanent as the other types of growing structures discussed. My family and I have had plenty of experience with hoop houses (a close relative of the polytunnel) and we could tell you that it has been a tremendous help in that it ensures a longer growing season and excellent protection for the plants despite its simplicity and lo-tech structure.

Geodesic Dome Greenhouses

A personal favorite of mine-- geodesic dome greenhouses are so innovative and functional that some people actually use the geodesic dome structure for houses! A geodesic dome is basically a half sphere structured by a bunch of triangular supports. They truly are unique in their appearance which is more than just aesthetically appealing, but efficient as well. They are a lot like greenhouses in the sense of materials, for example, you can use either a plastic or more glass-like exterior (polyethylene or polycarbonate glazed panels).

There are many advantages to using a geodesic dome as a growing structure, most of which correlate with that of the greenhouses. For example, they are highly efficient, less at risk of temperature changes, and attract maximum light. To supersede the advantages of a typical greenhouse though, a geodesic dome has a shape that allows wind to flow around it, snow easily slides off, less surface area allows for less escaping of heat, more space for tall plants, and overall there is a maximum space enclosed with the minimum materials used.

Sadly, these structures are not as frequently used as typical greenhouses, hoop houses or polytunnels are. Why? For one, they can be VERY expensive. Also, they are not that easy to assemble. This is not a growing structure for beginners. Just like with the regular greenhouses, you will want to make sure you have a plan and near sure-fire way to earn back what you put in by using the dome-house. Fortunately, a lot of different planting techniques can be used within a geodesic dome greenhouse. Hydroponics, the popular growing method for dome-houses seem to do real well in them. After some research, I've found that concentric circles of growing hydroponic beds are popular and a great use of the space. Planting horizontally or vertically is not really an efficient way to grow in a geodesic dome greenhouse, so you must learn to adapt with the shape. As an added note, Geodesic Dome Greenhouses are mostly intended to be placed on gravel or a concrete slab.

There is a growing structure out there for everyone! You just have to know what you're looking for, how much you're willing to spend on it, and most importantly, make sure you invest in one you are completely happy with opposed to spending thousands of dollars on something you intend on being short term.

Greenhouses vs. Polytunnels vs. Geodesic Dome Greenhouses (The Breakdown):

Greenhouses (typical)

-YEAR ROUND growing season

-EASY to assemble

-PROTECTS plants from the elements and soil borne diseases

-FLEXIBLE to your planting techniques

-EXPENSIVE to build and heat

-Glass vs. Polyethylene

Polytunnels (close relative to the hoop house)

-EXTENDED growing season

-VARIETY of crops

-CHEAPER option

-EASIER to assemble

-MOVEABLE for crop rotation

-MORE space

-ASTHETICALLY unappealing

-CHALLENGING to heat and ventilate

-VULNERABLE to the elements and people

Geodesic Domes (greenhouse)

-ASTHETICALLY appealing

-HIGHLY efficient

-LESS SUSCEPTIBLE to temperature fluctuations

-EVEN heat distribution

-MORE space for tall plants

-SAFE from the elements

-EXPENSIVE to build

-Polycarbonate Glazed Panels vs. Greenhouse Plastic

-DIFFICULT to assemble

"Homesteading at Rustic Farms" Learn how we built our hoop house and grow produce all year-round!

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