Lawn and Landscape Fertilizers

Decoding Fertilizer Numbers

Whether it's a bag of lawn fertilizer, tree and shrub fertilizer, or a jar of houseplant food you will be using, the three numbers in bold print on any of these containers are known as fertilizer grade. They always refer to the same nutrients in the same order.

The first number is the nitrogen content of the fertilizer; the second is phosphorus, and the third is the potassium content. Secondary nutrients are usually listed in finer print.Learn about the role of water in fertilizer absorption.

Choosing Fertilizer

Choosing a fertilizer depends on what you are fertilizing. Turfgrasses are heavy nitrogen users so fertilizers for grass have more nitrogen in them than any of the other nutrients. By contrast, trees, shrubs, annual and perennial flowers and even houseplants do not need as much nitrogen.

Zero Phosphorus

Although phosphorus is an important nutrient for plants, particularly stimulating root formation and growth, it is banned for use on turf in Minnesota except in certain cases.

Organic Does Not Mean Natural

An organic fertilizer simply contains carbon as part of its chemical make-up. There are many synthetic fertilizers on the market that can correctly be called organic. You can't assume that a fertilizer is all-natural just because it has the word "organic" on its label?

Which Is Better?

A plant doesn't care where its nutrients come from. Both types of fertilizers, synthetic or natural, are effective if applied correctly, and both can damage a plant if applied incorrectly.

Natural fertilizers are not normally used by turfgrass professionals because it takes nearly twice as much natural fertilizer to provide the same amount of nitrogen as a synthetic type. The increased amount of fertilizer also may increase the amount of potentially harmful salts, heavy metals, and weed seeds. Learn more from the University of Minnesota.