Importance of NPK Ratio in Hydroponic Nutrients


It is extremely important for hydroponic growers to have a thorough understanding of plant nutrition. While working with a soil-less system, it is not sufficient to just supplement the plants by providing extra fertilizer. It is important to ensure that the plant receives everything it needs.

Soil is a natural source of decaying organic matters and numerous minerals. Fertilizers are added only to provide additional nutrition for the plants.  However, the case is completely different in a hydroponic system. Until you start adding the nutrient solution, all you have in the system is water.

Plants require two types of nutrients that are differentiated based on the quantities in which they are needed. Macronutrients are the nutrients that plants require in higher quantities. On the other hand, nutrients that are required in lower quantities are known as micronutrients.

What is the NPK Ratio?

NPK is an acronym representing nitrogen, phosphorous, and potassium, three extremely important plant nutrients. These are the top three macronutrients required by plants throughout their growth cycles. As a grower, your focus should be on getting the NPK ratio right because this is how you can provide the right amount of nutrients to your plants.

While purchasing fertilizers, you will observe that each brand has its own NPK ratio. This ratio represents the nitrogen, phosphorous, and potassium percentage present in that particular fertilizer. Just like any other product, all fertilizers are not the same. Your hydroponics efforts will surely receive a boost by understanding the different NPK ratios. Reading this ratio is not at all difficult. If a certain fertilizer has a 7-9-5 NPK ratio, it means that the fertilizer provides seven, nine, and five percent nitrogen, phosphorous, and potassium respectively. Please remember that fertilizer may contain up to twenty different plant nutrients. Therefore, nine percent of phosphorous content is undoubtedly a big deal.

Vegetative State NPK Ratio: During the vegetative state of plants, the best NPK ratio is 7-9-5. Fertilizers with this NPK ratio help develop dark, green leaves and lush and plentiful foliage, and are commonly referred to as grow fertilizers.

The higher nitrogen concentration in this NPK ratio helps boost the vegetative state of the crops. The presence of additional nitrogen also helps improve the plant’s overall growth until harvest. Hydroponics nutrient solutions or fertilizers marked as “vegetative” or “grow” are ideal for growers looking to speed up their plants’ healthy maturation.

Flowering Stage NPK Ratio: The flowering stage of a plant refers to the stage when the vegetative components, flowers, and fruits start forming.  This is the phase when hydroponic growers should start preparing for the harvest.

In general, plants require more phosphorous than nitrogen during the flowering stage. Phosphorous is essential for healthy root structures, which plays a critical role as the plants start growing flowers and fruits. Potassium is another vital nutrient in this stage to watch out for. An NPK ratio of 5-15-14 can be a good choice in this stage of plant growth. During the flowering/fruiting phase, plants don’t need as much nitrogen because they tend to absorb and store adequate amounts of nitrogen for the future during the vegetative stage.

Other Commonly Used NPK Ratios:

It is impossible to figure out all the NPK ratios that are suitable for hydroponics setups because the chemistry behind it is extremely varied. However, mentioned below are some of the more popular ones to provide you an idea.

  • General Purpose: 10-10-10 is the NPK ratio of general-purpose fertilizers used for an established system that only requires supplementation with equal portions of three nutrients.
  • Hyper-chargers: Also known as bloom boosters, these fertilizers have an NPK ratio of 0-50-30. Be careful about using these fertilizers because they can alter the pH level of a hydroponics system, if not used properly.
  • Transition Ratios: During the transition from the vegetative stage to the fruiting or blooming stage, combine your two formulae taking 50 percent from each batch.

If you are looking to find out more about hydroponic systems, you may seek more useful information from Agron.