Plants don't just need sunlight and water. Plants require nine macronutrients to survive:
Soil provides some of these macronutrients, but full plant health usually requires fertilizer. Nitrogen (N), Phosphorus (P), and Potassium (K) are considered the fertilizer elements and appear as the NPK rating on most fertilizer labels. The ideal rating varies for different types of plants. The NPK rating describes how much of a fertilizer is comprised of these three elements by volume.
While each element serves other roles, Nitrogen generally facilities strong leaf growth, Phosphorus encourages flowering, and Potassium helps root growth.
Plant health will suffer if there are macronutrient deficiencies. It is important to supplement the macronutrients (and micronutrients) in soil with the right fertilizer. Humane simplifies the science so that it's easy to select the right organic fertilizer for the type of plant you want to grow.