How to Mix Fertilizer
 

I have this granular fertilizer that states an application concentration of 1 tsp per gallon for my orchids. I have this little applicator set to apply at 5.3 ounces of concentrate per gallon. I have calculated that the concentrate should contain approximately 1 cup of the granular fertilizer per gallon of water to get the final concentration of 1 tsp per gallon. Could some math-minded individual refute or verify my calculation please?

what's the N number ?

The Nitrogen number in the fertilizer formulation is 20. I assume that's what your asking, however that number is not required to perform the calculation unless you know something I do not, which is certainly possible!

If you want one teaspoon per gallon in the final solution, and your proportioner is fixed at 5.3 ounces per gallon, 5.3 oz = 31.8 teaspoons, so that's how much you'd need per gallon in the concentrate, which is 0.6625 cups.

Picking up on our little Martian's thoughts, for a 20-x-x formula, that's an awful lot - I'd never use more than half that, and then only if I only fed every couple of weeks)

Using the 1/3 to 1/2 of manufacturer recommended dose, that works out (for feeding every 2 weeks).