Help the development of the site, sharing the article with friends!

The NPK fertilizer; a mystery to many, essential nutrients for healthy plants to experienced gardeners. Also known as a complete fertilizer, this form of fertilizer is one of the complex fertilizers and has different ingredients that can differ in composition from plant species to plant species. They work effectively for garden or house plants and in the greenhouse, making them essential once applied correctly, effectively limiting potential downsides.


NPK fertilizers are special fertilizers, the concept of which came up in 1927 with the product Nitrophoska by the German chemical company BASF SE from Ludwigshafen am Rhein. The goal of these fertilizers was to provide the necessary core nutrients for plants in a concentrate that was easy to administer. The three main components of NPK fertilizers not only define the composition, but also give the fertilizer its name. These are the ones listed below.


nitrogen (N)

Nitrogen is one of the most important substances for plants of all kinds, as it is essential for plant metabolism and growth. Nitrogen enables basic processes within the plant, such as the formation of shoots, leaves and flowers, and is just as important for the overall vitality of the crop. The following problems arise when there is not enough nitrogen.

  • Chlorophyll cannot be formed sufficiently
  • this in turn leads to pale plant parts and metabolic problems
  • the formation of vital vitamins and proteins is made more difficult
  • Stunting is possible
  • Side shoots and shoots are only sparsely formed
  • vegetative and generative plant parts are usually formed smaller
  • Leaves often turn yellowish
  • if the deficiency is too great, the leaves will dry up and be lost
  • Fruits are only sparsely formed
  • this affects the yield and the quality of the fruit at the same time
  • if the deficiency is not remedied, the plant may die

With all fertilizers, however, it is important to ensure that the amount required for the respective plant species is not too small or too large.

Too much nitrogen leads to the following complications:

  • too fast growth
  • thin leaves and shoots
  • weak growth
young plants

Phosphorus (P)

Phosphorus is used in relation to nitrogen for the formation of strong roots, fruit and flowers and can be limited by too much nitrogen. In addition, phosphorus drives photosynthesis, which is vital for all plants. Another advantage of the substance is the beneficial effect on winter and frost hardiness. Plants that need a lot of phosphorus, such as fir trees, can easily survive the winter thanks to the substance. Phosphorus is also used for germination, as the substance provides the necessary energy for this. A phosphorus deficiency causes the following symptoms.

  • Ripening of fruits is slowed down, sometimes completely restricted
  • Fruits are only sparsely formed
  • Roots grow weak, brittle or not deep enough
  • all growth is retarded
  • also has a negative effect on the quality of the fruit
  • Leaf edges turn blue, green, blue-green, red, red-violet
  • Discolorations later spread to the entire sheet

Too much phosphorus in mineral fertilizers leads to chlorosis, a plant disease that limits or completely eliminates the use and formation of chlorophyll.

Potassium (K)

Potassium is the third substance in the group and is essential for water absorption and water balance, as well as resistance to diseases, fungi and viruses. In addition, potassium promotes the vitality of the plant parts and resistance to extreme weather conditions such as drought and permafrost.

A potassium deficiency is immediately evident through the following symptoms:

  • Fruits, buds and flowers are weaker
  • Plant parts appear limp because the cell walls are not strong enough
  • fewer roots are formed
  • Leaf edges turn brownish
  • Leaf edges and tips appear burnt
  • less water is absorbed
NPK is a compound fertilizer

However, it can also lead to an increased dosage of potassium, which leads to the following problems.

  • Substrate salty
  • Minerals such as magnesium can no longer be absorbed

Together, these three substances result in the so-called NPK value, which is listed on the packaging of the NPK fertilizer. The NPK value indicates the mixing ratio of the ingredients, i.e. the fertilizer composition. The amount of the substance contained is given in three numbers, each of which represents the percentage of nutrients in the total mixture.

Two examples:

  • NPK fertilizer for green plants: 14-20-8 (composition of 14% N, 8% P, 20% K)
  • NPK fertilizer for flowering plants: 7-6-8 (composition of 7% N, 8% P, 6% K)

As you can see, in general, green plants need more potassium and nitrogen, while flowering plants need sufficient phosphorus. In addition to these substances, it also contains other nutrients that the plant needs for numerous processes.

  • calcium
  • magnesium
  • sulfur
  • Trace elements, including zinc, iron, copper and numerous other nutrients

The more specialized the fertilizer is for a plant species, the different the compositions can be. However, the additional nutrients are rarely listed in their direct amounts.

Plant in fresh substrate

They are made in the following forms:

  • fluid: mostly for the home, above all indoor and potted plants
  • solid (granules in different sizes): mostly used for gardens and larger areas, has a long-term effect

Of course, the fertilizers can be used among themselves for any form of husbandry, but the right granule size should be chosen for solid fertilizers.

In addition, the NPK fertilizers are offered in three variants:

  • mineral
  • mineral-organic
  • organic

Depending on the type of plant, you should also pay attention to this point, since not every plant tolerates organic or mineral fertilizers.

Please note: Depending on the manufacturer, the individual numbers may be mixed up. While an NKP fertilizer is the same as an NPK fertilizer, you should pay attention to the order in which the substances are listed so that you don't accidentally confuse the potassium with the phosphorus content.


The NPK fertilizers are extremely easy to use, as they are available in a ready-to-use form and do not have to be mixed by yourself. Only a few points need to be observed during application in order to achieve optimal fertilizer performance.

Spread fertilizer in the bed

To do this, proceed as follows:

  • Time: Fertilize once in spring to prepare for the growing season
  • NPK long-term fertilizers are usually re-fertilized once in midsummer
  • with conventional variants, fertilize according to the needs of the plant or the manufacturer's instructions
  • Last fertilization at the beginning of July so that the new shoots can sprout and do not freeze to death over the winter
  • when fertilizing, follow the manufacturer's instructions for amount
  • alternatively, read through fertilizing instructions for the respective plant species
  • Liquid fertilizer is administered via the irrigation water
  • Distribute NPK lawn fertilizer with a spreader, as this makes the distribution more even
  • Granules are weighed prior to distribution
  • This will prevent over- or under-fertilization
  • the granules are distributed in the soil around the plant
  • you can easily start at the base of the stem
  • but do not damage the roots near the surface
  • if the soil is dry, it must be watered immediately after applying the fertilizer
  • on rainy days this step is not necessary

Tip: If you have roses, hibiscus, hydrangeas or summer lilacs, you can fertilize them with a calcium-based fertilizer (potassium fertilizer) after July. This strengthens the winter hardiness of the plants and is particularly effective for these plants.

When using the application, you should avoid the following mistakes:

  • never apply the fertilizer to the leaves, flowers or roots
  • this leads to acidification and potential death of the affected areas
  • avoid days when the sun is particularly strong
  • here too, acidification could occur due to the sun's rays
  • likewise, the floor should never be bone dry
  • do not over-fertilize; particularly important for mineral-based fertilizers
Plant young plants


The NPK fertilizer is one of the simplest and most effective fertilizer variants thanks to the ingredients and availability.

The following advantages can be mentioned:

  • Basic services are covered
  • Fruit yields increase visibly
  • more and healthier flowers are formed
  • Plants can use the fertilizer immediately
  • this does not have to be converted by microorganisms or otherwise
  • easy to use
  • Nutrients are optimally tailored to the needs of the plants
  • also acts as a long-term fertilizer


The advantages outweigh the disadvantages, but there are clear disadvantages that stand out when using NPK fertilizers.

  • usually more expensive to buy
  • significantly more energy is required for production, which can have a negative impact on the environment
  • Chance of over-fertilization quite high

Help the development of the site, sharing the article with friends!