NPK fertilizers are essential for plant growth in hydroponics. Your plants will not thrive and survive without these 3 essential macronutrients. Every green leafy plant needs NPK for growth (type and size don’t matter).

To understand NPK better let’s go deep inside these macronutrients.

What is NPK fertilizer?

If you can remember your chemistry class you will know the NPK stands for Nitrogen, Phosphorous, and Potassium. These are the 3 main nutrients that every plant on the planet requires to grow healthy and to produce yield.

If you ever buy a hydroponic nutrient bottle or pack you will notice NPK ration is written on the front part. This indicates the amount or percentage of these 3 nutrients in that pack of nutrients

hydroponic nutrients

As you can see in the picture, 3 numbers are written on the front of each bottle 2-1-6, 5-0-1, 0-5-4.

The first digit tells us the percentage of nitrogen in the solution whereas second and third tells about the percentage of phosphorous and potassium in the same bottle. Every nutrient bottle has mentioned NPK in the same order.

Zero mean that nutrient is missing in the bottle.

In the second bottle, zero is in the middle that means from NPK P is missing means phosphorous is not added in the formula.

Every fertilizer has at least one of these in the formula. For example, lettuce growers use 10-0-0. This means only nitrogen is present in 10% of total value and 90% are other micronutrients.

Do plants only need NPK to grow?

The answer is no, plants do need many other micro or supporting nutrients to grow. As you can see if you add the NPK ration, it does not make 100% of the product. The remaining are the other micronutrients in the fertilizer bottles.

Mainly plants need following primary nutrients to grow

Carbon (Co2): They take carbon dioxide from the environment.

Hydrogen: Plants take it from the water you supplied to them.

Oxygen: Plants get oxygen like us means from Air and also from water (H2O)

Nitrogen: Nitrogen is one of the essential nutrients that plants need the most in the first face of growth. It helps plants to produce the plant proteins in high quantity that helps them to form new tissues, new branches, new leaves. This is the reason plants needs nitrogen in high quantity in the vegetative stage.

Once your plant produces enough green leaves then you can move to the other nutrients that encourage flowers and fruits. If your plant is nitrogen deficient it will not grow strong and does not produce greens. The most important nutrient for green lettuce is nitrogen. If you are growing lettuce at home you need to give your lettuce nitrogen in the large amounts. You will see long and healthy lettuce leaves in a few days.

Phosphorous: If you are growing plant has to produce seeds, flowers or buds you need to give phosphorous in high quantity. Plants with a strong rooting system always grow big and healthy. The one nutrient that your plant needs to develop a full complex system of roots is phosphorous.

In hydroponics, you need to keep the pH level between 6 to 6.7 for the better absorption of phosphorous. If due to any reason the pH drops below 5.5 the roots of the plant will not absorb it in the required quantity. This results in less strong flowers and lesser yield.

Potassium: Potassium generally improves the immunity of plants. In simple words, this nutrient makes plants strong enough so that they can fight with many diseases on their own. It also regulates the many metabolic activities in plants. In the veg stage, your plant does not require potassium at a high percentage. So, for the Veg stage choose a fertilizer with high nitrogen and low potassium and phosphorous.

Organic NPK or synthetic

In hydroponics, you can use any fertilizer of your choice. Organic fertilizers are cheap to use whereas synthetic ones are a little costly. But there are two problems with organic NPK fertilizers. In hydroponics plants do not take up the NPK directly from the reservoir because organic nitrogen, phosphorus, and potassium comes with many other attached nutrients.

So, your growing system needs to break the NPK from other attached nutrients and for that, you need a colony of bacteria.

Do this:

Mix the organic NPK in the reservoir, let the bacteria to build up in the solution (it takes minimum10 hours). Then turn ON the hydroponic system and let the nutrient solution circulate into the system. Once it circulates the system for 5 minutes, now put your plants into the system.

The problem is you need to flush the hydroponic water every 7 days and by doing so you are also flushing the bacterial colony. This way you need to build up the colony again before using the second batch of nutrients.

The second problem is many organic fertilizers produce a bad smell when they react with organic decaying bacteria.

Synthetic NPK Fertilizer:

Ready to use NPK fertilizers are best to use in hydroponics. They give instant nutritional boots to your plants and full fill all nutrient deficiencies. They are made in such a way that plants can easily absorb them along with water. You will have beautiful, thriving plants by supplying them with synthetic nutrients.

Synthetic fertilizers are made by processing the raw material, it can be plant-based or animal-based.

Along with the NPK, your plants also need some other supporting nutrients like Calcium, Magnesium, and sulfur.

Micronutrients are required in very little quantity and every NPK fertilizer bottle has all of them included in the formula.

Boron, Copper, Zinc, Iron, Chlorine, etc are the main micronutrients

Use of NPK in Soil Gardening:

For those who use soil as a growing medium can use NPK 5-5-5 ratio. This is the perfect nutrient balanced form for every plant grown in soil. But before adding nutrients to the soil you need to test the soil of your garden. If the soil is deficient in nitrogen then choose high nitrogen nutrients.

Organic nutrients are a good choice for soil growers. Organic fertilizers also release nutrients at a slower rate this makes the continuous supply of nutrients to the plant. This is the reason plants grown in soil required less maintenance than those grown in hydroponics.