The Effect of Fertilizers on Radish Growth


Radishes need less fertilizer to grow than many other food plants. Applying a sufficient amount of fertilizers, however, speeds and increases the growth of roots and vegetative parts of the radish plant.


Nitrogen increases leafy growth and root size throughout the growth cycle of a radish. It also increases the rate of growth, allowing radishes to be harvested earlier. An excessive amount of nitrogen may cause leaf growth at the expense of root size.


Phosphorus stimulates root development and growth, which leads to a fleshier radish root. A lack of phosphorus in radish plants leads to stunted growth and poor yields.


Potassium reduces water loss by the plant and reduces stress due to droughts. This is important for radishes, because excessive water loss and drought can cause the root to crack, resulting in stunted and poorly formed roots. Potassium also increases root growth, which results in larger radishes.


According to a study on radishes published by the Institute of Soil and Environmental Sciences, an integrated use of nitrogen and compost increases overall plant growth and yields when compared to other fertilization methods. It also improves the efficiency of chemical fertilizers so that less is required for the same result.

Organic Fertilizers

Organic fertilizers act in much the same way as compost, providing a full balance of nutrients and chemicals that increase radish size. Many organic fertilizers have a higher concentration of nitrogen than compost, and so do not need the addition of extra nitrogen to achieve a similar effect as compost integrated with nitrogen.


Do not overuse fertilizers, because this could lead to chemical toxicity in the radish and inhibit radish growth and development. Test the chemical composition of the soil to determine which nutrients are already readily available.


  • Rainbow Plant Food: Nitrogen
  • California Fertilizer Foundation: Plant Nutrients--Phosphorus
  • Indian Journals: Mobility of Phosphorus and Its Impact on Radish Top Development
  • California Fertilizer Foundation: Plant Nutrients-Potassium
  • Institute of Soil and Environmental Sciences: Study on Radishes

Who Can Help

  • Canadian Ministry of Agriculture, Food and Rural Affairs: Radishes--Fertility
Keywords: radish fertilizers, improving radish growth, fertilizing radishes, growing bigger radishes, radish plant size

About this Author

Samantha Belyeu has been writing professionally since 2003. She began as a writer and publisher for the Natural Toxins Research Center, and has spent her time since as a landscape designer and part-time writer. She holds a Bachelor of Arts in English from Texas A&M University in Kingsville.

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