NPK Fertilizer

In conjunction with terms such as fertilizer, garden, plant nutrients, etc., the letters NPK or the term NPK value always come up. What do these obviously important terms mean and what kind of influence do they have on beautiful, healthy flowers and robust and (or) high-yielding plants?

The letters are the chemical symbols for the three major components of NPK mineral fertilizers (compound fertilizers, complete fertilizers):

    „N“ is the chemical symbol for nitrogen. Nitrogen takes on an array of different functions in the plant and is therefore particularly important. Mainly, it is responsible for plant growth and regeneration. If there is too little nitrogen present, the plants do not grow sufficiently and any yield decreases. An excess, however, has several disadvantages: it leads to delayed flowering and fruit ripening; plant tissue becomes very soft and therefore less stable; and eventually, diseases and pests are more likely, which is what leads to a reduction in yield.

The letter „P“ refers to Phosphorus, which is also a main nutritional element in plants. The essential functions of phosphorus care for the transmission and storage of chemical energy, as well as root formation. In addition, it is essential for photosynthesis. Thus, phosphorus is helpful from the beginning, meaning that it supports the seed, for example, during fertilization. But also later during the blooming period. A lack of phosphorus causes plants to remain small and stunted and stalks to remain thin. What's more, the leaves turn color, the roots hardly grow and flowering is delayed. In contrast, a (rarely occurring) excess of phosphorus damages the plants indirectly, by reducing the amount of trace elements available.

The letter „K“ stands for Potassium, the third essential nutrient. This material provides for water absorption and thus for an appropriate balance of water in the plant. That also leads to strong plant tissue and a high resilience and resistance. At the same time, it promotes resistance to diseases, extreme weather conditions, such as the cold, etc. A lack of potassium makes the plant become limp and impairs formation of the root. In addition, the plant transpires more during dry periods and takes less water. Too much potassium causes a disadvantageous concentration of salt and thus a reduced intake of positive nutrients, such as magnesium, etc. In addition to the three main nutritional elements mentioned above, which are present in large quantities in NPK fertilizer, plants still need other important nutrients such as calcium, magnesium and sulfur, and trace elements (copper, zinc, iron, etc.) for growth and the formation of biomass. Therefore, these are also found in fertilizers, but only in smaller amounts.

Since not all plants have the same nutritional needs, there are NPK fertilizers with different compositions. That is, the specific material that is especially important for the plant is present in the fertilizer at a higher percentage or in a greater concentration.The different compositions are distinguishable from each other by a series of numbers on the product, the so-called NPK value.

For example, green plants benefit from a fertilizer with a value of 7-3-6 (7% nitrogen, 3% phosphorus and 6% potassium) or 14-8-20, whereas for flowering plants that require an increased amount of phosphorus, for example, a 7-8-6 or 6-8-7 fertilizer is recommended. The ratio of nutrients to each other is important because the nutrient concentrations are very different, changing the frequency with which you have to fertilize.

Note: The numerical values and the nutrient ratios are meant as guidelines - not more. Following the guidelines strictly and rigidly is neither necessary nor possible because you cannot know the precise needs of the plant anyway. You know just as little about the content of the substrate, in which the plant is growing. For this reason, a preemptive soil analysis is sometimes recommended.. It can help us to learn exactly how the soil is composed and what nutrients might be missing. NPK fertilizer should be used primarily when the plant needs very many nutrients. This especially the case in the growth phase, but is not limited there. The reason for this is the fact that many soils and substrates at that time have a lack of Phosphor, Potassium & Co. or do not receive these nutrients over the course of time, insufficiently providing for good and sufficient plant growth.

NPK fertilizers are available in solid (micro granules, granules) and liquid form. For plants it is actually irrelevant what fertilizer you choose, as long as the composition is the same. Nevertheless, both types have advantages and disadvantages:



Solid NPK fertilizer delivers its nutrients slowly. Thus, it has a long-term effect, which many horticulturalists appreciate. Rain does not wash it out of the ground as fast. Thus, it is ideal for outdoors. This kind of fertilizer is usually administered to the plants through the so-called process of top-dressing, which means that the product is sprinkled evenly over the entire surface of the soil and not worked into it. Deep fertilization is only preferable for deep-rooted plants (such as fruit bearing plants and trees) in order to supply the roots with more speed and effectiveness. Using solid fertilizer also raises the question of point fertilization.

Liquid NPK fertilizer is mostly used with potted plants and rarely with outdoor cultures. Then, both the watering method (liquid fertilizer is added to the water) and point fertilization, which supplies selected individual plants, come into question. Another method is the so-called foliar fertilization method (onto the underside of plant leaves), which is only recommended for a few plants (e.g. orchid and tillandsia).



Conclusion: Compound fertilizers (NPK) have, apart from the slightly higher price, many advantages. They are easy to use and rich in nutrients; they should be used where there is a specific lack of all the main nutrients. If that is not the case, you can also use binary fertilizers or nitrate fertilizers. These have only two (e.g. potassium and magnesium) or even just one essential nutrient (e.g. nitrogen) and are therefore often not as expensive as NPK fertilizers.