I was reading up a few weeks ago on fertilizing and someone, somewhere said that grinding down egg shells would be a good idea to increase calcium in the soil.

Now this made me save some egg shells and peanut casings. My question is, without grinding them down, would it be a good idea to mix it into the soil when planting plants like peppers for example? Would the same apply for, for example, banana peals?

The reason I ask this is because my brother said he wouldn't do it since potting soil already has an over abundance of nutrients and it would likely damage the plants.

  • It sounds like you are talking about composting in a pot with a growing plant. Could be a possible recipe for insects, mold etc. Also, how do you determine the NPK of a banana peel? I think there are easier/less risky ways to feed your plants.
    – Tim Nevins
    Commented Jan 15, 2018 at 14:17

2 Answers 2


I doubt that eggshells well make any difference to your potting mix. I used to see these years later in the compost heap still intact unless it's been quite acidic.

As for organic matter such as banana peels they will slowly decompose in the mix releasing nutrients. Organic fertilisers like this don't usually harm plants unlike inorganic fertilisers which can cause nutrient burn.

  • So in short, it might be a good idea to include banana peals for nutrients, perhaps the peanut shells for drainage but the egg shells won't do anything, correct?
    – Tikkes
    Commented Jan 16, 2018 at 10:28
  • I didn't say it was a good idea :) Your potting mix should already have enough nutrient to get things started, and the slow decomposition of these things may not provide enough nutrient to keep going. I just don't see much harm in it, and it might provide enough material for things like earthworms to survive in your pots. Commented Jan 16, 2018 at 20:26

If you take your eggshells, & soak them in a bowl of vinegar, it will begin the process of breaking them down a lot faster, ... as the vinegar will react to the calcium in the shell, ... & it will look as if it is boiling the shell bits, ... Ever do any pickled eggs? This does the same thing, by making the shells rubbery, ...lol, ...

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