I am new to gardening and am trying to figure out how much fertilizer to use. There aren’t any instructions for the fertilizer I’m using on how much to use for potted plants but after reading, it looks like people are putting in fertilizer based on the size of the pot.

But shouldn’t we add fertilizer based on the size of the plant? Any advice would help, I still have no idea what I’m doing or how much to add.

I planned on digging a little trench around the plants and putting 1 tablespoon of fertilizer all along the trench.

Extra details: the plants I am currently growing are beans, spinach, and lettuce. They are all in 5 gallon containers and the fertilizer I am using is Fertilome gardeners special 11-15-11

  • Welcome! While asking a generic question about principles is fine, I would guess that with more information about the specific plant(s) and type of fertilizer we could give you advice that’s better tailored to your situation.
    – Stephie
    Sep 3, 2020 at 18:20
  • I just added some extra details! Sep 3, 2020 at 18:22

1 Answer 1


Without more details, we can’t tell you how much fertilizer you should use. Concentration and time-release can vary significantly. But we can explain why some fertilizer instructions are based on the pot size, not plant size.

A pot size equals a certain volume of soil. Adding a certain amount of fertilizer translates to a specific ratio of fertilizer to soil, e.g. grams per liter. Too much fertilizer for example can “burn”, i.e. damage the roots, too little is obviously not effective. Now one could argue that each plant would need fertilizer based on plant size (and nutritional needs, but that’s a different topic) but then a good gardener will match the container volume to the plant size, so that in the end a dosage based on pot size is good enough.

  • Oh okay thanks for the reply. That makes sense then. I guess some of this is just trial and error Sep 3, 2020 at 18:20

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