Also essential to plant growth are three elements: nitrogen, phosphorus and potassium. These three are commonly referred to by their atomic element symbols—N for nitrogen; P for phosphorus; K for potassium—which you will see written on bags of fertilizer.
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Nitrogen is the element that promotes growth in the green parts of plants—specifically leaves and stems. While that vibrant growth can look great, an overabundance of nitrogen comes with a downside. It can make plants grow too quickly, hurting root development and restricting fruit growth.
What nitrogen does for leaves and stems, phosphorus does for roots. Like nitrogen, there can also be too much. Excess phosphorus in the soil can get into the ground water and cause serious pollution problems.
Potassium is important for general health, especially for the oldest parts of the plant.
Promote better pH and element levels in your soil.
To find out your garden's soil makeup, buy a soil testing kit (make sure to get one that also measures nitrogen, phosphorus and potassium) from a hardware or gardening store, and check in on it throughout the growing season. Another option is to get your soil professionally tested. This will cost a bit, but you'll get more accurate and detailed results.
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