The polders of Baie du Mont-Saint-Michel produce many vegetables. Made of tangue, a mixture of sea alluvium, sand, and silt, their soils have flexibility and a constant humidity rate. Irrigation and forcing are, therefore, unnecessary to produce slightly sweet vegetables like carrots, potatoes, and onions. The Maison des Polders (House of polders), in Roz-sur-Couesnon, explains the traditions linked to this method of organic cultivation.