NO WARM BEER!
German brewers discovered that lagers, when fermented between 33 and 55 degrees Fahrenheit, produce much purer beer. The Brauordnung (laws pertaining to the brewing of beer) are often traced back to the year 1539, but Franz Hofer, who teaches German history at Cornell University explained by email to the Atlantic, that the “decree limiting beer-brewing to the time between the feast of St. Michael [September 29] and that of St. George [April 23] wasn’t promulgated until 1553.” The decree came from Duke Albrecht V and applied only to Bavaria, the southeastern region that contains modern-day Munich. The decree was designed to protect the public from fires that were common in the hot summer months throughout Europe. Bavarian "Fachwerk" architecture comprised almost wholly of wood burned easily and the Duke feared that the coal fires used to heat the brew kettles would cause fires to break out across the countryside.
Brewers began digging deep cellars close to river banks to store the lagers during the winter months to fill the demand for beer in the summer months when brewing was prohibited. They spread gravel over the ground and planted large trees to maintain the temperature during the summer months. Local townspeople would come to buy the beer and many stayed to consume the frothy beverages on the grounds beneath the trees, the beer garden or biergarten was born.
The beer garden became a place for people to come enjoy their beer of choice and picnic outside. These social constructs became so popular that innkeepers and tavern owners began to complain to local authorities that they could not compete with the beer gardens because the breweries sold the beer directly to the public.In response to this Maximilian I, the King of Bavaria, signed the "Compromise Decree" restricting breweries from selling any food other than bread. The backlash from the public was swift and resolute, they began bringing their own food to picnic and the beer garden was born.