A greenhouse, or glasshouse as they are commonly known, is a glass or plastic enclosure where plants and crops can be grown. A glasshouse is typically a metal structure with glass panels forming the roof and walls so the optimum amount of sunlight can get to the plants inside. This works by solar radiation being absorbed by the plants through the glass and then being retained inside the building to circulate. By just opening one small window in the glasshouse, the temperature drops drastically and can be used as a cooling mechanism for the plants- this shows us just how effective the glass is at trapping heat.

Glasshouses can range from being small boxes in the back garden of homes to great big buildings with a computer regulated cooling, heating and watering system.

Not only does the glasshouse regulate the temperature of the plants, it also protects them from rain and storms, and keeps out any pests or animals that may damage or eat the plants. Because certain plants and food crops can be grown in glasshouses all year round, this makes them an ideal choice for high latitude countries that have trouble growing crops- Spain, for example, has some of the largest greenhouses in the world and over 200km2 of Almeria is covered by greenhouses.

When warm weather vegetables or flowers are grown in glass houses during the winter the temperature and water supply needs to be carefully controlled to maintain the illusion that it is summer before they can be moved outside into the soil when summer genuinely arrives. This enables us to sell certain foods and flowers all year round without delay.

The idea of using a glasshouse like structure to grow crops all year round has existed since Roman times, when the emperor Tiberius would have cucumber everyday because his gardeners would keep the crops outside in the sun during the daytime, but move them into a heated room and cover them with oiled cloth on a night time. However, the first real instance of the glass house we know today originated in 13th century Italy when travellers would bring back exotic flowers from abroad and keep them in "Giardini Botanici" (aka, a botanical garden) to preserve them. This soon spread to countries like Holland and in the early days there were a lot of problems regulating the heat accurately, but eventually a Frenchman named Charles Lucien Bonaparte created the first working glasshouse. Today, Holland has over 9000 greenhouses which cover around 0.25% of their country and produce almost 4.5 billion Euros worth of plants and vegetables- 80% of which they export to different countries.

Over the years other countries picked up on this, with the French using them a great deal for fruit and even building one outside the palace of Versailles. By the 19th century, huge glasshouses were being built and England experienced a surge of affection for places like Kew Gardens and eventually the Eden project. It was in the 1960's, however, when steel and PVC plastic became more easily accessible, that glasshouses (now commonly made of plastic, however) became a common sight in most home gardens. Gradually they became more sophisticated, with double layers of plastic to preserve heat better, and even built in water pumps to water the plants automatically.