Greenhouse How-to, Myth-busting, and Pros and Cons

A tailor-made greenhouse is probably something every gardener or vegetable farmer dreams he had. The genius concept of artificially creating an optimal environment for plant growth is something that has been known to be around since the Roman era. Of course, we may think of greenhouse construction as simply throwing up a frame and stretching some see-through plastic sheeting over it, but there’s more to it than just that.

There are various styles and types of greenhouses, but the general idea is to erect a system of framework that will support glass or plastic sheeting. This glass or plastic can either be completely transparent or it can be translucent. But it shouldn’t be opaque as this would defeat its cornerstone purpose of admitting into the greenhouse, the sun’s radiation.

Although the sun’s rays initially enter the greenhouse via radiation, the primary mode of heating inside greenhouses is convection. Radiation enters the greenhouse through the transparent roofing and walls, and is absorbed into the various plant-life and soil, translating into heat. This heat is then released into the greenhouse

Eden Project, UK

atmosphere via convection, thereby raising the temperature. (Convection/Radiation)

Building the greenhouse is the easy part – comparatively speaking. In order for greenhouses to be the most effective, the temperature, humidity, UV lighting, irrigation, pest and disease-control must all be optimized. Nowadays this is often done by computer software to ensure accuracy. But essentially, all you need is a basic knowledge of what environment the particular plant you’re trying to grow needs, and provide it to the best of your ability.

A thermometer, hygrometer, and vents are some things you won’t be able to do without. Although monitoring the temperature and humidity of your greenhouse is something you can do with simple tools, boosting or reducing the temperature by large amounts is something you’ll need additional equipment for. Also, providing a proper irrigation system is essential unless you want to be watering it manually yourself everyday – or TWICE a day in fact.

Greenhouse Myth #1

Greenhouses are only used by “rich” or 1st world countries because they’re greedy and want to have strawberries all year-round.

– Hmm, although the “greedy” and “wanting to have strawberries all year-round” may be true to some extent, this is not the ONLY reason greenhouses exist! Many high-latitude or inarable countries and regions depend greatly on greenhouse production for their very survival!

Greenhouse Myth #2

Greenhouses are responsible for the “Greenhouse Effect”!

Illustration of The Greenhouse Effect

– False again! The greenhouse effect is simply the process of greenhouse gases – water vapor, methane, carbon dioxide, ozone, etc – absorbing thermal radiation and re-radiating it back in all directions, thus adding significant temperature to an otherwise -18 degrees Celsius average. That’s right, without the “greenhouse effect”, life would be VERY cold! The average temperature on the Earth’s surface is about 14 or 15 degrees Celsius – which means the greenhouse effect is responsible for raising the heat by about 33 degrees! – Cozy!

Well, I’m certainly not complaining about that! I never liked frostbite.

Although fundamentally different, the connection between the greenhouse effect and greenhouses is the fact that the former “traps” heat via greenhouse gases, and the latter does the same via its transparent roofing and walls. The environmental hype surrounding the greenhouse effect is caused by the rise in mean temperature due to large artificial emissions of greenhouse gases by modern industry, namely, carbon dioxide. (More on Why greenhouse gases are called greenhouse gases.)

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