Farm trials of four crops are not due to be known until September
The first of six government organised debates on genetically modified (GM) crops begins at the NEC in Birmingham on Tuesday.
The nationwide debate - called GM Nation? - aims to persuade small local groups to set up their own meetings to discuss the controversial issue of growing GM crops.
Whitehall ministers backed hundreds of field trials for GM crops in the 1990s.
Now the government wants to gauge public opinion before deciding whether the crops can be grown commercially.
Birmingham Friends of the Earth said it was pleased members of the public were being consulted but feared the whole thing was nothing more than a PR exercise.
The organisation's Jenny Thatcher said: "All we can hope for is that they listen to what the public is saying.
"If the public don't want the commercialisation of GM crops, we have to hope the government will have the strength and political will that they won't commercialise GM in the UK."
Although the debate ends in July, the results of the farm-scale trials of four crops proposed for Britain, carried out over the last four years, are not due to be known until September.