The ban on the purchase of booze at petrol stations, kiosks or supermarkets comes in an effort to prevent an increasing number of alcohol-fuelled crimes in the southwestern state.
“We must put an end to the nightly alcohol binges, aggression and violence,” Baden-Württemberg Interior Minister Heribert Rech said, adding that drinking in public areas frequently leads to fighting in the streets.
Bars, restaurants, and airport terminals are excluded from the ban, and communities will also have the right to suspend it for festivals and markets if they wish.
The state-wide ban comes after a Freiburg court overturned a city ban on public alcohol consumption in July 2009. The southern university city, along with many other German cities, instituted the ban to prevent violence and crime.
Heidelberg, Magdeburg and some parts of Berlin have also cracked down on public drinking in the last two years with varying degrees of success. The bans are part of a broader attempt to curb excessive underage drinking.
But Germany's federal drug commissioner Mechthild Dyckmans has been hesitant to approve of Baden-Württemberg's alcohol ban initiative, voicing fears that young people would simply stock up on alcohol to skirt the new rule.