How To Make and Apply Potassium Nitrate Foliar Spray on Mango Trees

 Learn how make potassium nitrate spray and how to apply potassium nitrate on mango trees.  Most mango trees produce flowers in alternate years, but some varieties bear fruits every year.  Sometimes the mango tree fail to produce any fruits for several years in spite of taking all the care because their fruiting cycle is disturbed (No fruits on mango tree, induce flowers on mango tree).

The effect of applying potassium nitrate on mango tree would be make the trees bear fruits or induce more flowers on the tree [1-6]. This spray can double or even triple the fruit production and larger fruit [2]. It can also allow some trees to fruit twice in a year.
Potassium nitrate
Potassium nitrate

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Things You Need To Make Potassium Nitrate Spray

  1. Potassium Nitrate Powder,
  2. Sprayer
  3. Protective gloves and eyewear
  4. A ladder for tall trees

How To Make Potassium Nitrate Foliar Spray

Make 2 to 3 % potassium nitrate spray solution/

Potassium Nitrate Recipe

The question is how much potassium nitrate per gallon or litre of water is adequate for mango trees. 6.4 tablespoons or 3.2 ounces of potassium nitrate per gallon of water is needed to make 2.5 % potassium nitrate spray solution.
The following potassium nitrate recipe is for making 2.5 percent solution.
  1. Potassium nitrate: 6.5 tablespoons
  2. Liquid Soap: 1 ml
  3. Water: 5 litre
Adding 1 g urea in the nitrate solution may yield better mango yield.

How To Apply Potassium Nitrate to Mango Trees

  1. The forcing of mango fruits or blooms by Potassium Nitrate spray is only for healthy mango trees at least 10 years old.
  2. The method is effective on shoots that are between 4.5 and 8.5 months old and flowers can emerge within seven days after treatment.
  3. Do not spray on young trees or on new growth or when tree is flowering.
  4. Spray on a cloudy day or in evening.
  5. Do not spray in Sun, leaves may burn or when raining or may rain within 6 hours of spray. Cut the concentration of nitrate in half in sunny weather or on mature trees that already have dormant buds.
  6. Application should be made prior to emergence of the flowers, never spray the tree while it is flowering because the nitrate can damage mango blossoms. 
  7. Spray thoroughly both sides of leaves, branches and trunk. Coat each area well.
  8. Spray a second time after 15-20 days if the response to the first spray shows no results.
  9. How to Spray on Tall Mango Trees
    1. Use a ladder to Spray on tall trees.
    2. Spray the uppermost branches first and then spray down. 
Flower buds should appear after 10 days to two weeks. 

Calcium nitrate (2-3 %) can be sprayed instead of potassium nitrate to get good results [3]. 

Application of paclobutrazol (6g/tree) in soil and foliar spray of potassium nitrate 8 weeks after paclobutrazol treatment can result in a significant increase in flowering and and foliar spray of potassium nitrate 8 weeks after paclobutrazol treatment very early flowering [6].


1. Barba, RC., Induction of flowering of mango by chemical spray, Crop Sci. Soc. Philippines Proc.5:154-160 1974.
2. The Scientist, the Patent and the Mangoes - Tripling the Mango Yield in the Philippines 
3. GV krishna, et al., Foliar Chemicals Application Impact on Flowering and Yield of Mango 4. Mike A. Nagaol and Melvin S. Nishina, Use of potassium nitrate on mango flowering
5. T. Yeshitela, P. J. Robbertse & P. J.C. Stassen, Potassium nitrate and urea sprays affect flowering and yields of ‘Tommy Atkins’ (Mangifera indica) mango in Ethiopia, South African Journal of Plant and Soil, 22:1, 28-32  (2005) DOI: 10.1080/02571862.2005.10634676
6. Tongumpai, P., Jutamanee, K. and Subhadrabandhu, EFFECT OF PACLOBUTRAZOL ON FLOWERING OF MANGO CV. KHIEW SAWOEY (1991)