[Martin]

All the purple beans that I've seen described turn green when cooked. (I'm growing 'Cosse Violette' this year). Anyone know if there is a variety that stays purple when cooked?

[GrannieAnnie]

I'm not an expert on french beans, but I think all the purple varieties turn green when boiled, but maybe stay a bit purple if steamed?

[crowndale]

I tend to stir fry and they stay mostly purple with patches of green!