The fire started Tuesday afternoon at the farm just east of Rivière-du-Loup.
Witnesses up to 100 kilometres away said they could smell the smoke, which was so heavy six families were forced to leave their homes.
Water bombers from Quebec's forest protection service flew in to help douse the flames as firefighters from several local communities worked on the ground.
Saint-Modeste Mayor Louis-Marie Bastille said it could take days to put out the fire completely.
By Wednesday morning, crews had the flames mostly under control, but the fire continued to smoulder below the surface.
Bastille said once the fire is out, they will have to continue to keep an eye on the peat for several days.