Liverwort and mosses can be found in many greenhouses where plants are highly irrigated and fertilized. Their presence is exacerbated when there is high nitrogen in the upper soil surface, such as by top-dressing. These types of plants reproduce by spores and vegetatively and are easily spread throughout a greenhouse. They can compete with the crop for nutrients and water and can also create a barrier on the potting media surface that restricts water movement into the container resulting in poor irrigation efficiency and increased runoff. Decreasing the amount of water applied and avoiding top-dressing, as well as inspecting plants before they come into the greenhouse, can reduce the presence and impact of liverwort and mosses.