Fertilizer Mixing Calculators

Home > Free Information > Fertilizer Mixing

If you have referred to our Fertilizer PPM Calculators, you are aware of the significance of using those values to control your feeding regimen.  Don't forget however, that while such calculations give you information about the solution you use, they tell you nothing about just how much nutrition you are giving your plants overall.

As was discussed in our article on Feeding by Mass, it is necessary to think about feeding your plants just as you think about yourself.  For example, you know that as an adult you may need to take in an average of 2000 calories a day to maintain good health and weight.  Eat too much at one meal, and you might back-it-off at the next.  You certainly wouldn't want to eat three, 2000-calorie meals a day, would you?  If you think about a fertilizing as providing "a meal" to your plants, you can apply a similar, logical approach to your feeding regimen - keeping in mind, of course, that a watering with plain water - a "flush" - is a "zero-calorie meal.

We believe smaller, more frequent feedings are better, as they provide an adequate supply of nutrients without the risk of "burning" the root system.  Not only that, but a frequent, dilute solution is pretty effective at flushing wastes and precipitated minerals from the medium, as well.  Our experience agrees with that of the orchid grower at Michigan State University that feeding with a 125 ppm N solution two- or three times a week is a good regimen for a varied collection of actively growing plants.  If we maintained that watering frequency, but occasionally "flushed" the pots with plain water, that concentration would have to be adjusted to maintain the sail nutrient application.

The calculator below will help you figure out what your concentration should be, when using your particular supply of fertilizer.  If you use a proportioner, you can use the calculator below to determine how much fertilizer to mix in your concentrate tank.

One last thing:  in all cases, when you see that you are to mix "X" amount per gallon, the proper mixing is to add the fertilizer, then fill the container to the gallon mark, not to add the amount to a gallon.

Mixing Calculator

Nitrogen content from
fertilizer label (first number)
% N
Target nitrogen level in final solution
(you may change this recommendation)
ppm N
Typical number of times you water,
with- and without fertilizer
times/month
Typical number of times you flush
with plain water
times/month

The Results:

 teaspoons per gallon, or    milliliters per liter
giving you a final solution of
ppm N

Mixing Calculator for Proportioners

Nitrogen content from
fertilizer label (first number)
% N
Target nitrogen level in final solution
(you may change this recommendation)
ppm N
Proportioner Ratio : 1

The Concentrate should be:

 teaspoons per gallon, or    milliliters per liter