With the barbecue season in full swing, the meat-free proposal by the opposition Greens was skewered across the political spectrum, string embroidery with one leading politician asking 'What's next? Green-Shirt Day?'

But the Greens argue that reducing meat consumption - 60 kilos on average in Germany a year - would have health benefits in a country known for its love of sausages, as well as an upside for animal protection and climate change.

Their manifesto for the September 22 elections calls for public cafeterias to take on a "trailblazing" role. "Offerings of vegetarian and vegan meals and a 'Veggie Day' are to become the norm case for samsung galaxy," it states.

"One doesn't have to eat two burgers every day," one of the Greens' leading election candidates Katrin Goering-Eckardt said on Monday, as scientists in London presented the world's first lab-grown beef burger.

So far topics such as tax increases, minimum wage, childcare and the euro have dominated an election run-up in which Chancellor Angela Merkel's conservatives have maintained a comfortable lead.

However, with Germany's electoral system based on coalition-building, smaller parties have kingmaker potential and the Greens are currently set to stick with their traditional partners, the embattled centre-left Social Democrats.

Michael Fuchs, deputy chairman of the conservatives group in parliament, railed against the notion of having an individual decision taken away.

"Bit by bit, according to their (the Greens') image of society, the state assumes more and more functions, decrees more and more bans," he said in a statement.

"What a presumptuous plan!" scoffed mass circulation Bild newspaper. "Whoever wants responsible citizens must also treat them that way. And must not constantly try to re-educate them," it commented on Tuesday.

According to the Sueddeutsche Zeitung newspaper, the northwestern city of Bremen introduced a 'meat-free Thursday' scheme three years ago and several big companies have similar days aimed at reducing carbon dioxide emissions.

Around eight million people, nu skin product or about 10 per cent of the population in Germany, are meat-free, according to figures by the Vegetarian Federation of Germany.