I live in an apartment building, and all my plants grow in pots or small flower beds. Since I moved here, 7 years ago, I have only watered the pots and revolved the "soil", eventually adding more vegetable compost to fill the pots.

I believe that a splash of NPK fertilizer would be good, but I am concerned about poisoning the plants. Is there a possibility to overdo the amount of such nutrients? What kind of damage could happen?

  • I'd ask what plants you're growing, whether they're edibles or not for one thing, difficult to give an answer without that info. At the moment, seems like the risk of overdosing on NPK fertiliser is nil, given you're not using any at all. You also haven't reported any problems with the plants - are there any?
    – Bamboo
    Commented Sep 4, 2014 at 15:49
  • There are edibles (sage, parsley, rosemary, lemongrass, lime - a small tree) and decorative plants (lavender, geranium). No issues with the plants to be reported, but they could look more strong.
    – Morts
    Commented Sep 5, 2014 at 20:27

1 Answer 1


Yes excess NPK can damage plants, although how much N, P, or K is too much depends on the plant.

For example, you shouldn't add too much N to the soil for radishes and carrots because that will causes them to grow lots of leaves and small vegetables. Conversely, grass-type plants, like corn, and vegetables you grow for their leaves, like kale and lettuce, will use a ton of Nitrogen.

For general knowledge, I recommend you read all the questions tagged .

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    Yes. Plus, you can burn roots with too high a concentration of fertilizer, especially nitrogen. As long as the plants in question are regarded properly, and the fertilizer instructions are followed carefully, there shouldn't be any problems.
    – J. Musser
    Commented Sep 3, 2014 at 21:02
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    And if you live in the right areas, Potassium can build up and poison plants. So don't just apply a supposedly balanced fertilizer and not test your soil. You may find that it's balance is terribly askew as your production falls off from blindly applying it. Commented Sep 4, 2014 at 1:26

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