Fertilizer Recommendations

In this article I just note applications of various fertilizers. It is mainly to help myself to refer quickly as I can look into this article as needed. I may update this article as need to add or update info.

Solution Preparation

We need to mix 10 gram of fertilizer with 1 kg of water to get 1% solution.

As per Wikipedia: At standard pressure, one liter of water has a mass of 0.999975 kg at 4 °C, and 0.997 kg at 25 °C.

So, generally we can take one liter of water as 1 kg water.


Nitrogen, Phosphorous and Potassium are major major macro nutrients required by plants.

  • Nitrogen
    • Nitrogen is an essential element of all the amino acids in plant structures which are the building blocks of plant proteins, important in the growth and development of vital plant tissues and cells like the cell membranes and chlorophyll.
    • Nitrogen is a component of the chlorophyll molecule, which enables the plant to capture sunlight energy by photosynthesis, driving plant growth and grain yield.
    • Nitrogen plays a critical role within the plant to ensure energy is available when and where the plant needs it to optimize yield. This nutrient is even present in the roots as proteins and enzymes help regulate water and nutrient uptake.
    • Nitrogen is a component of nucleic acid that forms DNA a genetic material significant in the transfer of certain crop traits and characteristics that aid in plant survival. It also helps hold the genetic code in the plant nucleus.
  • Phosphorous
    • It is involved in several key plant functions, including energy transfer, photosynthesis, transformation of sugars and starches, nutrient movement within the plant and transfer of genetic characteristics from one generation to the next. It is believed essential for seed formation and development.
    • When P is limiting, the most striking effects are a reduction in leaf expansion and leaf surface area, as well as the number of leaves. Shoot growth is more affected than root growth, which leads to a decrease in the shoot-root dry weight ratio. Nonetheless, root growth is also reduced by P deficiency, leading to less root mass to reach water and nutrients.
    • Other effects of P deficiency on plant growth include delayed maturity, reduced quality of forage, fruit, vegetable, and grain crops, and decreased disease resistance.
  • Potassium
    • It stimulates the growth of strong stems and gives the plant some disease resistance by promoting thickness of the outer cell walls. Adequate potassium can reduce moisture loss from growing plants, thereby giving some drought resistance. Potassium improves colour, flavour and storing quality of fruit and vegetables.
    • Potassium is associated with the movement of water, nutrients and carbohydrates in plant tissue.
    • If K is deficient or not supplied in adequate amounts, it stunts plant growth and reduces yield.
    • Increases root growth and improves drought resistance.
    • Maintains turgor; reduces water loss and wilting.
    • Aids in photosynthesis and food formation.
    • Reduces respiration, preventing energy losses.
    • Enhances translocation of sugars and starch.
    • Produces grain rich in starch.
    • Increases plants’ protein content.
    • Builds cellulose and reduces lodging.
    • Helps retard crop diseases.
  • Balanced – 1-1-1 (Advised for Matured Plants)
    • Examples: NPK 18-18-18, NPK 19-19-19, and NPK 20-20-20
  • Boosted Growth – 2-1-1 (Only advised for Seedlings)
  • Rooting – 1-2-2 (After repotting)
  • Flowering – 1-2-1 (Once a month for matured plants only)

From: https://www.orchid-tree.com/blogs/beginners-corner/what-do-the-numbers-on-fertilizer-mean-fertilizer-npk-ratios

I guess 1 g per liter (0.1% solution) would be safe to use all NPK fertilizers, but not sure though.

Half teaspoon NPK 20-20-20 per gallon is recommended at https://homeguides.sfgate.com/dilute-powder-202020-fertilizer-houseplants-98417.html. Which is 50 mg per liter.

MKP – Mono-potassium Phosphate – NPK 00-52-34

Phosphorus and potassium are needed more in early growing stage for the establishment of root system.

On young leaves, spray concentration of 1.0% is recommended in most crops. On mature leaves and more tolerant crops, concentration of 2.0% may be applied. From https://www.haifa-group.com/haifa-mkp%E2%84%A2-mono-potassium-phosphate-0-52-34. Which means 5 gm per liter of water.

When applied as foliar spray, MKP acts as a suppressor of powdery mildew.

It should not be mixed with calcium or magnesium fertilizers. Iron, manganese, zinc and copper must be in the form of chelates.

SOP – Sulfate of Potash – NPK 00-00-50-S17.5

As other NPKs, 1g per liter would be safe.

MAP – Mono-Ammonium Phosphate – NPK 12-61-00

Recommended for use at the beginning of the growth season. On young leaves, a spray concentration of 0.5% MAP is recommended. On mature leaves and more tolerant plants a higher concentration (1.0% or more) may be applied. From https://www.haifa-group.com/haifa-map%E2%84%A2-mono-ammonium-phosphate-12-61-0

Temporarily acidifies the soil.

Urea – NPK 46-00-00

Not to be used generally when we apply other NPK fertilizers, especially when NPK has nitrogen.

Urea should not be mixed with ammonium calcium nitrate (CAN), KCl, SSP or TSP.

Urea can be mixed with most other fertilizers but fertilizer mixtures containing urea should be applied immediately after mixing. Do not store fertilizer mixtures containing urea.

Most urea foliar sprays are between 0.5 percent and 2 percent urea. So, we need to mix 5g of urea with 1 liter of water to get 0.5% solution.

Epsom Salt – Magnesium Sulfate

1 tablespoon per gallon is seen as usual recommendation, which is around 14.3 g per 4.5 liter. But I guess 1 g per liter is safer in most plants.

Ammonium phosphates and super phosphates should not be mixed with lime, slag, rock phosphate or CAN. Should not be mixed with calcium or magnesium fertilizers


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