Question: what does npk stand for on fertilizer bags?
Answer: 'NPK' stand for Nitrogen, Phosphorous, K for Potassium or Potash. '5 – 3 – 5' are the ratios of NP&K in the pack or bottle. In this case 5 parts Nitrogen, 3 parts Phosphorous, 5 parts Potash. The ratios vary depending upon the intended use of the plant feed, and the amount of each source that is added to the mix.