If, like so many others, it was your first gardening during the pandemic, you have probably already figured out that it means more than just planting a few seeds or baby plants and letting nature work its magic. Sure, you may be aware that using fertilizer, for example, can help your plants grow, but you may not know (or have heard of) the numbers given for different types of fertilizers.
As it turns out, the three digits on the front of the fertilizer packages actually mean something. In one current article for BobVila.comMark Wolfe gives us the key to this fertilizer code.
Where are these fertilizer numbers and what do they mean?
The not so secret fertilizer codes are located on the front of the packaging and consist of three digits separated by hyphens (e.g. 3-2-1). These are the fertilizer’s NPK numbers, which, according to Wolfe, match the nutritional information on food – with the exception of the nutritional value of a specific fertilizer for plants.
According to Wolfe, there are 16 known essential nutrients for plants, and the three most important are nitrogen (N), phosphorus (P), and potassium (K). That is why they are prominently placed on the front of fertilizer packages:
The three NPK numbers on a fertilizer label indicate the percentage by weight of each item in the package. In other words, a pack of 24-0-6 fertilizer contains 24 percent nitrogen, 0 percent phosphorus, and 6 percent potassium. The rest of the package contents are made up of other nutrients (listed somewhere on the label) and / or inert ingredients.
Once you know the percentages of each item in a fertilizer bag, you can determine the weight of each item in it. This calculation is useful when you have your soil tested and have been instructed to modify your soil with a certain amount of a certain element.
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What does each nutrient do to plants?
Depending on the combination and concentration of the three elements, some fertilizers are better suited than others for certain plant and soil conditions. Therefore Wolfe says it’s helpful to understand the role each element plays in plant growth and how to choose a fertilizer with the right nutritional balance for your horticultural needs.
Here is a quick rundown of the properties of each element: Courtesy Wolfe::
Nitrogen (N)
- Feeds foliage plant growth
- Used to help lawns grow and keep their green color
- Trees and shrubs don’t need as much nitrogen as they only grow one set of leaves per season
Phosphorus (P)
- Stimulates root, flower and fruit development, especially in annual flower beds, fruit plants (such as tomatoes) and newly planted seedlings
- However, if your soil already has a decent amount of phosphorus, adding more can harm your plants
Potassium (K)
- Promotes strong stems, well-formed flowers, sturdy fruits and healthy roots
- Helps plants use water and withstand drought
Read the rest of Wolfe’s article to learn more about fertilizers and how to choose one with the right combination of nutrients for your garden.
