Plant Fertilizer Basics

Milorganite fertilizer's steady release of nitrogen helps flowers keep their color.

Plants need to be fertilized because most soils do not provide the essential nutrients required for optimum growth. Even if you are lucky enough to start with great soil, as your plants grow, they absorb nutrients and leave the soil less fertile.

By fertilizing you replenish lost nutrients and ensure your plants have the food they need to flourish.

Fertilizers come from many sources. Synthetic fertilizers are manufactured from minerals, gasses from the air, and waste materials. Organic fertilizers, like Milorganite, obtain their nutrients from natural sources such as microbes, organic wastes, and other similar materials. Learn more about the differences between organic and synthetic fertilizers.

There are six primary nutrients that plants require. Plants get the first three—carbon, hydrogen and oxygen—from air and water. The other three are nitrogen, phosphorus and potassium. Using the below chart, you can determine the percentages of these nutrients in a fertilizer. A 5-4-0 fertilizer like Milorganite is 5% Nitrogen, 4% Phosphorus and 0% Potassium.

Essential Nutrients
Nutrient Nutrient Properties
N - Nitrogen Governs overall plant health and growth above-ground. Accelerates growth and deepens the green color in grasses. Too much Nitrogen makes plants grow quicker than their roots can support.
P - Phosphorus The essential element for strong root development. Plants with proper amounts of Phosphorus are also more resistant to disease and have improved seed production, fruit growth, blooming and flowering.
K - Potassium Potassium plays more of a behind-the-scenes role than Nitrogen or Phosphorous, but still is necessary for optimizing plant health. Potassium improves water retention and disease resistance while protecting plants from cold weather.

This video shows how to select a fertilizer.