Luckily, commercial fertilizer contains guaranteed amounts of the essential nutrients that plants need.
The numbers on commercially produced fertilizers indicate the percentage of each main ingredient in the mixture.
What Does NPK Stand For?
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NPK in fertilizerstands for nitrogen (N), phosphorous (P), and potassium (K).
Nitrogen promotes healthy leaves and green foliage growth.
Phosphorous helps roots, flowers, and fruit growth.
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Potassium encourages stronger stems and fast growth.
What Do Fertilizer Numbers Mean?
The Spruce / Ellen Lindner
The actual numbers on the fertilizer label often vary slightly from the chart above.
The Spruce / Ellen Lindner
Organic fertilizers are typically less concentrated than synthetic fertilizers, so the numbers will be lower.
For example, an organic bulb fertilizer with the numbers 3-5-3 contains more phosphorus than nitrogen and potassium.
Fertilizers are made with different nutrient ratios to suit specific plant needs.
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Fast Facts
What Nutrients Should You Look For?
Most fertilizer contains nitrogen, phosphorous, and potassium with additional micronutrients and fillers.
Fertilizers often contain some of the more than a dozen other nutrients.
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Without asoil test, it’s possible for you to only guess what you actually need.
Avoid Over-Fertilization
If in doubt, start with a weaker fertilizer and lower quantities.
Over-fertilizing your plants, such as an over-fertilized lawn, can be just as detrimental as too little fertilizer.
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The following quick checklist will help you determine which fertilizer you need:
Organic vs.
Conventional fertilizer can come from a variety of different sources, but it is made from inorganic material.
They are usually fast-acting and water-soluble.
While they can help give your plant a nutrient boost, they won’t necessarily improve the soil quality.
If you apply too much conventional fertilizer, you could risk burning/damaging your plants.
However, they will not damage your plants.
A homeowner’s guide to fertilizer.
North Carolina Department of Agriculture.
2, 2017, pp.
5, 2019, pp.
- doi:10.3390/plants8050119
Understanding soil pH.
