Does putting eggshells in your garden really help your plants grow? Will the calcium in the eggshells give your plants an extra boost? Let’s see what the experts and the scientific research have to say.
There is a lot of advice for gardeners that is either exagerated, misleading, or one of many garden myths, and we all fall for them at some point!
Should We Add Eggshells to the Garden?
Click play to listen:
- The popular advice to improve plant health with eggshells is misleading (modern garden folklore).
- The idea that calcium is deficient in soil, that eggshells instantly provide it, and plants take it up and flourish are all problematic.
Soil tests rarely indicated calcium deficiency. If a plant is truly calcium deficient, it is often an uptake problem, which is not solved by adding more.
- Eggshells are just one of many organic foods we can compost, contributing micronutrients and structure, taking many years to break down.
Fine to include in compost (like many other things) but not a magical superfood.
- Correlation is not cause: just because you added eggshells and plants did well does not mean that was the cause.
Do Eggshells Really Give Plants a Boost?
So, are eggshells good for your garden? Plenty of people think so, but the short answer seems to be, no, not really, and whatever benefit they theoretically might provide can be much better achieved in other ways.
It’s easy to understand why this gardening myth refuses to die.
Eggshells are calcium!
Calcium’s good for you! Builds strong bones!
So, let’s put it in the garden!
And, it’s not entirely a myth. Your plants do need calcium and eggshells provide it—that part’s true! But, there’s probably plenty of calcium in your soil already, so adding more calcium isn’t going to help at all.
And, even if extra calcium would help, eggshells aren’t the best way to do it.
Unless you grind them to a very fine powder, they’re just going to sit in your soil as broken eggshells for years until they decompose.
Now, they will eventually decompose, so maybe they’ll help your plants many years from now—again, only if your soil was calcium deficient—which it probably won’t be.
That said, the eggshells aren’t going to do any harm, and composting them is better than sending food waste to landfill, but just don’t expect to see any improvements in your garden because of them.
If anyone tells you their plants changed quickly after adding eggshells to the soil, now you know that the eggshells were not the cause.
Calcium and Blossom End Rot
You will sometimes hear it said that adding eggshells will prevent what’s known as blossom end rot, a problem that shows up during some tomato growing seasons.
This condition does relate to calcium uptake and moisture stress (uneven watering) but is usually not caused by calcium deficiency in the soil.
More commonly, the problem is that the plant isn’t absorbing the calcium that is in the soil, and adding eggshells isn’t going to address that problem.
Low soil pH levels and over-fertilizing may also play a role. If the problem persists, this is where a good soil test from an accredited lab can provide a complete analysis and any recommendations.
Related: Soil Testing: Home Kits versus Lab
So, it may sound good, but no matter how many times you’ve heard this one, and will continue to hear it, the best evidence we have says that adding eggshells is not going to provide any benefit to your garden. Or, at least not any of the benefits that popular gardening advice claims they do.
Keep composting but never expect miracle cures from single additives like this.
~Melissa the Empress of Dirt ♛
- Using Eggshells in the Garden and Compost | University of Illinois Extension
- Can I Compost Hard-Boiled Eggs? | Extension.org
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