Detergents can affect plant growth, but the effects depend on the type of detergent and the ingredients in the detergent itself. Some common ingredients that could negatively affect plant growth are sodium and bleach. Detergents are also often alkaline, which can increase the pH of soil, decreasing plant growth.
The effects of detergent are not always negative, depending on the plant species and detergent ingredients. For example, many detergents contain phosphates, which are an essential nutrient and can be a limiting factor in plant growth, especially in aquatic environments. In lakes and streams, vegetation can benefit from additions of phosphorous to the water, causing accelerated plant growth.