In cold climates, a greenhouse can add an additional month or more of growing at the beginning and end of the season. This is especially useful in climates where many vegetables can't grow because the season is not long enough for the plants to reach maturity. The use of a greenhouse to harbor these vegetables means you can grow a wider variety.

Starting seeds in a greenhouse is the perfect way to jump-start the growing season. Waiting for the weather to be warm enough for seeds to be planted outside cuts down greatly on the available time for growing. When they are started in the greenhouse, they have time to become hardy seedlings before being transplanted outdoors.    

Greenhouses are also useful when you have plants that need a specific temperature year-round. Depending on daily temperatures can be stressful since mother nature doesn't always maintain the steady climate that a particular plant needs. A greenhouse, on the other hand, can be temperature regulated and conditions managed specifically to optimize plant growth.

There are many types of greenhouses for sale to choose online, and it is good to think about your needs before purchasing one. Small, simple, transferable greenhouses are great for small garden operations. They can be folded up and stored over the winter making them a great choice for renters or other situations where a permanent structure won't work. Other factors to take into account include the weather conditions where you live and how much space you will need. If you live in a particularly windy area, you will need a heavier duty greenhouse.   
 
Most gardeners who would be interested in a four season greenhouse would also want to have a sustainable source of heat instead of being dependent upon fossil fuel, wood or electricity. There are several ways to increase the temperature inside a small greenhouse without the use of purchased fuel. You won’t even need solar panels to provide enough heat to grow vegetables in the winter with these ideas.

A greenhouse is truly a must-have for any serious gardener. It serves a variety of purposes and makes the gardening experience much easier and enjoyable.