A method of cultivating aquatic plants (104) at the surface (107) of a body of water (106), the method comprising: - cultivating the aquatic plants (104) in a basin (108) containing the body of water (106); - supplying nutrient rich water (114) to the body of water (106) at a first location (112); - extracting purged water (118) from the body of water (106) at a second location (113) distant from the first location (112); - inducing movement of an aquatic plant portion (122) toward a collection region (124); and - removing the aquatic plant portion (122) from the collection region (124).