You might think this is a simple question... but there is more to a greenhouse than you probably think. There are three main reasons for using a greenhouse. Protection - greenhouses offer warmth and insulation protecting your precious plants from the harsh elements such as frost, snow, wind and hail. Wider crop variety - growing in a controlled environment such as a greenhouse means you can effectively cultivate a much wider variety of plants than you would normally be able to grow outside. Extended growing season - because of the warmth and protection you can start growing produce much earlier and (depending on your circumstances) grow right through winter compared to outside thus extending your growing season into the cooler months. A greenhouse also looks great, adds value to your home and offers a warm place for you to potter about on a rainy day!