Fertilizer labels and terms
• Brand and grade
• Guaranteed analysis
• Directions for use
• Name and address of registrant
• Net weight
There are many types of fertilizer. Before shopping for products, it’s good to understand some terminology.
What is N-P-K?
Fertilizers are labeled with three numbers, giving the percentage (by weight) of nitrogen (N), phosphorus (P), and potassium (K). This is referred to as the fertilizer grade. The remainder of the ingredients are fertilizer carriers such as sand or ground limestone, and sometimes micronutrients.
What do these nutrients do?
Refer to this chart for information on what each nutrient (element) does for the plant, and its sources.
The minimum amount of each element in a fertilizer as stated on the label. Example: 16-4-8
A fertilizer containing equal parts of each primary macronutrient (N-P-K). Example: 10-10-10
A fertilizer containing nitrogen, phosphorus, and potassium. Example: 12-4-8
A fertilizer missing one or two of the primary macronutrients. Example: 0-20-0
A fertilizer containing 30% or more primary macronutrients. Example: 33-0-0
Weed and feed fertilizers
A combination of fertilizer and herbicide; often used on lawns to prevent certain weeds from germinating, or to kill existing broadleaf weeds.
Fertilizer plus some other material with a different purpose; most often an insecticide or fungicide.
Quick-release or highly soluble fertilizers
Liquid or powder form, mixed with water, and applied at the base of plants or sprayed directly on foliage.
Makes nutrients available in small amounts over an extended period; may have a clay or polymer coating like sulfur-coated urea.