French police were left red-faced when they destroyed a hemp art installation at the Lyon Architecture Biennale, after mistaking it for a cannabis farm.

Artist Thierry Boutonnier and architectural firm ​Fabriques Architectures Paysages planted a mix of barley, hemp and flax on a derelict 4,000 sq m plot of land for the piece, titled Waiting Area.

‘The installation temporarily reactivates a place that in the future is going to undergo a profound change, but which today is dormant,’ says the biennale’s website.

Fête champêtre fin de @Biennalearchi par #FabriquesArchitecturesPaysages et T.Boutonnier 8 juillet 17h-23h. Infos : https://t.co/nlq3Q7fm22 pic.twitter.com/iToJ6lpwtI

— VAD (@assovad) June 30, 2017

Waiting Area was installed in the city’s Confluence district – a former industrial area undergoing significant regeneration – and it was meant to host the closing party for the biennale, which wrapped on 9 July.

According to news outlet Le Progrès, officers ripped up the crops after confusing them for the drug, which is illegal in France, on a routine patrol. Hemp has a much lower level of psychoactive-chemical THC than marijuana.

Read next: Hot pink houses cause a stir in LA