We all know what a greenhouse is; these structures are familiar sights to nearly everyone.
Whether you live in a large city or a rural area, you see greenhouses from time to time and perhaps every day.

• You already know that these are buildings which are designed to allow gardeners and farmers to grow plants indoors even in weather which would make it impossible to grow the same plants outside of the protective environment created by the greenhouse.
  
• You know that a greenhouse keeps plants safe from wind, rain and other precipitation as well as excessively high and low temperatures.
  

Greenhouses are used to allow gardeners to start young plants in the spring before the temperatures have risen to the point where it is safe to grow them outside.

• They are also used to enable plants to be grown later in the year which would be possible without a greenhouse as well as to overwinter plants which are not strong enough to live through harsh winter weather.
  

However, if you're reading this right now, what you're probably wondering is not what a greenhouse is or what it's for, but how it works.
As it turns out, it's actually pretty simple.
If you think back to your school days, you may recall most of what you're about to read.

• A greenhouse works because of the way that solar radiation (heat and light energy) travels through glass, plastic and other transparent materials.
  
• These are materials which sunlight can easily pass through to enter the greenhouse.
  
• The light can pass through the greenhouse easily, but the heat energy cannot escape from the structure so easily.
  
• Trapped inside of the greenhouse, the temperature increases and keeps the greenhouse and the plants inside much warmer than the air outside.
  

It's pretty easy to keep the air inside of a greenhouse warm, since it's a small area and the heat cannot escape easily.

• Another advantage of using a greenhouse is that not only is it easy for the greenhouse to retain heat, the warmer air inside can more easily retain moisture.
  The added humidity is a bonus for most plants; and between the warmth and humidity, a greenhouse is an excellent environment for growing plants, even when the weather outside becomes so cold that your garden wouldn't last a minute against the elements.
  

Greenhouses come in all shapes and sizes, so if you love gardening but hate having to stop working in your garden and enjoying your plants when the weather starts to turn cool, then growing in a greenhouse is something which you may want to give some thought to.