EU Directive 2015/412 [europa.eu] allows EU member governments “to restrict or prohibit the cultivation of genetically modified organisms (GMOs) in their territory” and as part of the transitional measures of the directive member states could overrule and exclude themselves from any EU-approved GMO by notification before the 3rd of October 2015.
The following 19 (out of 28) have done so:
Austria, Belgium for the Wallonia region, Britain for Scotland, Wales and Northern Ireland, Bulgaria, Croatia, Cyprus, Denmark, France, Germany (except for research), Greece, Hungary, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Poland and Slovenia.
From the Greenpeace link further below:
The bans currently notified apply to the only GM crop currently approved for cultivation in Europe – Monsanto’s pesticide-producing GM maize, known as MON810 – but also to the seven GM crops awaiting approval by the Commission.
Sources:
Reuters “Majority of EU nations seek opt-out from growing GM crops” [reuters.com]
RT “Two thirds of EU states reject GMO crops, file cultivation opt-out requests” [rt.com]
Deutsche Welle Europe's GMO compromise: bound to unravel? [dw.com] (discusses future developments in view of the news)
Greenpeace “Distrust over EU GM crop approvals grows as at least 16 countries move towards national bans” [greenpeace.org] (has a lot of additional information)