Nitrogen (N) 

Nitrogen is the most important element for the plants in their vegetative stage of growth, as it is necessary for the normal development of the stems and leaves. The highest concentration of nitrogen is found in the hydroponic nutrient solutions marked as “grow” or “flower”. The most vivid signs of nitrogen deficiency are yellowish, discolored, thin, and weak plants.

 On the other hand, plants between their growing stages can perfectly make it with the solutions containing half-strength nitrogen. Normal amount of the element in the solution is resumed once the plants switched to the “flower” stage. Such schedule will provide better blooming and will help avoid plants stretching and elongating.

 Phosphorous (P)

 Flowering and roots growth depend on the amounts of phosphorus supplied. If a plant lacks this element it grows very slowly, which postpones flowering and fruiting stages. Nutrient formulas designated for the “bloom” stage contain high concentrations of phosphorus and potassium.

 Potassium (K)

 Potassium is vitally important for the plants, in spite of the fact that it actually has no nutritional value for them. The matter is that this element is capable of promoting absorption of all the other nutrients by the plants. Potassium deficiency causes slow irregular growth and susceptibility of the plants to diseases and pests. Note that during the fruiting stage the amount of potassium should be significantly reduced, as it prevents fruits development. 

 Secondary Hydroponic Nutrients

 Calcium (Ca)

 Calcium enhances the absorption of other nutrients, but it is necessary for the plants mainly during the vegetative stage, while its supply is reduced in the flowering phase. Beside, this element may increase to some extend the pH level of the nutrient solution.

 Magnesium (Mg)

 Magnesium aids in the production of chlorophyll during photosynthesis; thus, its deficiency leads to the growth of yellow leaves and discolored stems.

 Sulfur (S)

 It is necessary to underline that yellow leaves may also be a sign of sulfur deficiency. However, this chemical is present in the nutrient solutions only in small amounts.

 Iron (Fe)

Lack of iron may as well result in yellow leaves. Its absorption may be reduced due to the high pH levels of the solutions; thus, it is one more reason to regularly check their pH. 

 Molybdenum (Mb)

 Molybdenum enhances the absorption of nitrogen and aids in the conversion of nitrates to ammonium.

 Boron (B)

 Boron does not belong to the essential elements; furthermore, it is not even present in the regular soils. However, it is said to help transport carbohydrates in the phloem; thus, it is sometimes supplemented in the nutrient solutions. Nevertheless, beware of the overdose of boron, as it may kill the plants.