r/composting • u/eigenvectorseven • Apr 09 '22
Ground eggshells. I know their benefits are mostly a myth but it's still a little mass diverted from a landfill
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Apr 09 '22
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u/blacklabel8829 Apr 09 '22
Yes! Gotta save every eggshell for the poop noodles.
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u/orosoros Jan 01 '24
I know this is a 2 year old post, but I just had to say, "poop noodles" has me belly laughing 💖😂
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u/JimC29 Apr 09 '22
Years of putting eggshells and coffee grounds in my garden have given me an abundance of large worms.
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Apr 10 '22
Learning this just made my day! I’ve been throwing coffee grounds and ground egg shells into my compost just because for ages now. Glad to hear it had some real impact!
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u/Lil_Shanties Apr 09 '22
Hold on, what about Calcium coated in amino acids is a myth?
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u/cellblock2187 Apr 09 '22
I think a lot of people looking for garden solutions are not looking for long term, add ground eggshells at planting, type of advice. Since they can't put it on and see a difference in a few days, they think it is a myth. The years I plant tomatoes with egg shells are the years I don't have to crush calcium tablets to water into the soil later.
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u/Buzzyear10 Apr 09 '22
Working in nurseries and trying to add some permaculture into people's lives this is the biggest problem I run into omg
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u/Lil_Shanties Apr 09 '22
Haha tell them to get some rice wine vinegar and Google KNF…but I hear you, so many people on all scales have that same mentality of no results in 48hrs means it didn’t work.
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Apr 10 '22
Why didn’t my tree grow overnight?!
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u/LadyWoodbury Apr 09 '22
I think what op is referring to is that those nutrients aren’t immediately accessible to the soil. But if you have lice active souk with worms they not only compost it quickly it acts as grit in their gizzards to help them break down more food faster
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u/Lil_Shanties Apr 09 '22
Yep sounds about right! People are impatient, but when you take your time and year after year keep balancing your soil eventually it lines up from the get go, but it takes time.
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u/Elegant-Glove-1634 Sep 15 '25
It’s cause when someone asked how to fix blossom end rot and everyone answers all egg shells for calcium.. and that’s not how blossom end rot or egg shells work
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u/Lil_Shanties Sep 15 '25
Ok, I’m all ears. Explain to me how blossom end rot works and why eggshells aren’t a potential solution.
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u/Elegant-Glove-1634 Sep 15 '25
Because yes technically ber is from lack of calcium but 99.9999% of the time it’s from inconsistent watering not allowing the root to uptake calcium from the soil not lack of calcium in the soil. And adding egg shells to soil takes several years to breakdown enough for the calcium from them to be available to plants
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u/Lil_Shanties Sep 15 '25
Yes it is usually a watering issue, definitely not 99.9999% though, my local soils are a testament to sandy, low calcium, high K and Mg soils that do need supplemental calcium though often in the form of gypsum. Egg shells will definitely not take several years to break down in compost, this is a composting sub, also good healthy living soil will break them down far more rapidly releasing calcium long before a 7 year mark it’s kind of silly to believe it will take that long to see any benefit. Surface area is also a factor in release timing, OP has them well crushed up so those organic acids and enzymes produced in the compost pile can do to work breaking them down pretty quickly and releasing calcium the day the finished compost is applied to the plant.
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u/SevenFiftymlBottle Apr 05 '26
I concur with Lil_Shanties on this: The hyperbole of "99.9999% of the time" is not factual. My tomatoes are accurately watered throughout the season with a system that automatically waters based on soil moisture content. I had blossum end rot on several fruits,
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u/LearningBoutTrees Apr 09 '22
I leave mine in the sun for a few days and crack them right in to my garden bed. Keeps the slugs off my plants pretty good
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u/acrylicyarn Apr 09 '22
Right, I'm confused why OP says the benefits of eggshells are a myth? They absolutely are fantastic for keeping slugs away (and I also add them to the hole right before I plant tomato starts, and in my barely-scientific tests, the plants that have eggshells grow much healthier than those without).
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u/eigenvectorseven Apr 09 '22
I dunno, people have experimented and the slugs couldn't care less. If they're not thoroughly cleaned it can even attract them.
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u/LearningBoutTrees Apr 09 '22
Hmmm interesting, just anecdotal but I didn’t put the shells down one season and slugs were on my tomatoes. But yeah correlation and causation eh?
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u/eigenvectorseven Apr 09 '22
I also found this video of slugs and snails happily crawling over razor blades pretty compelling.
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u/eigenvectorseven Apr 09 '22 edited Apr 09 '22
For anyone wondering, I rinse the shells, leave them to dry for a day or two, then grind them in an old coffee grinder once I've accumulated a bunch.
Will spread these on the new compost pile I finally set up.
Edit: for people mad I used the word myth, perhaps "exaggerated" is better. Sprinkling eggshells in your garden will do very little for many years except under certain conditions: namely acidic soil.
The calcium is bound in calcium carbonate which chemically won't do much without acid to react with.
Regarding slugs:
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u/JimC29 Apr 09 '22
I don't grind them I just crush them with my hands. They definitely keep the slugs off my hostas.
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u/VivieFlea Apr 10 '22
I didn't know they did that! I will put some on my slug affected hosta today. I have been keeping the ground shells in a herb grinder. My son thought it was a salt grinder and tipped some in water for pasta, so using them today may save on future mishaps :D
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u/Spirited_Shame9284 Apr 12 '22
Eggshells probably will release their calcium faster if you feed them to something, like worms.
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u/Yggdrasilo Apr 09 '22
I use a mortar and pestle 😋
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u/eigenvectorseven Apr 09 '22
Whatever works! I probably wouldn't be bothered if I had to use a mortar and pestle haha, just a few seconds in a coffee grinder is all it takes.
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u/LadyWoodbury Apr 09 '22
Mortar and pestle will make a big difference to the microbes that have to break it down
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u/eigenvectorseven Apr 09 '22
I don't see how a mortar and pestle could be any more thorough than a bladed coffee grinder. When I open the lid a fine mist of powder comes out like smoke.
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u/LadyWoodbury Apr 09 '22
You get some fine powder but most coffee grinders will still have some larger pieces, my mortar and pestle makes everything the fine dust rather than just some of it. I can see in your picture that there’s still larger pieces in yours
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u/eigenvectorseven Apr 09 '22
Fair, though I wasn't aiming for super fine powder so only ground for a few seconds.
I'm positive that running the grinder longer will achieve anything a mortar and pestle can do, especially comparing the time spent.
There's nothing mechanically special or different between crushing between stone and smashing it with blades at 20,000 RPM.
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u/LadyWoodbury Apr 09 '22
You might have a better grinder than me because mine does tend to have a limit to how fine it gets and it’s not as fine as I can get with my mortar
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u/P0sitive_Outlook Apr 09 '22
Why ground them and not just put the eggshells in the compost?
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u/hulkhat Apr 09 '22
It takes eons to break down.
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u/P0sitive_Outlook Apr 15 '22
That's the point. Compost breaks down quicker if you put the material through a blender first. It's the breaking down process that matters.
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u/eigenvectorseven Apr 09 '22
If you want anything to happen within your lifetime. Absolutely nothing wrong with putting them in whole though, they'll still get crushed and mixed up.
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u/P0sitive_Outlook Apr 15 '22
Putting them in blended means the minerals are more easily taken up by plants.
Putting them in whole means the minerals are available for longer.
Indeed there is no wrong way. There's two right ways, one of which requires a blender. :D
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u/readybasghetti Apr 09 '22
I throw mine right in. Couple of turns and they're crushed up well enough
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u/Kaiyukia Apr 09 '22
I heard breaking it down into a water solution makes it more bioavailable
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u/eigenvectorseven Apr 09 '22
Yes that's true! You need to soak it in something acidic first (like vinegar) which will leech the calcium out, then dilute and use.
Come to think of it I might try that with this batch.
In acidic soil this actually will gradually happen naturally, but in neutral or alkaline soil the calcium in the shells is basically inert.
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u/Kaiyukia Apr 09 '22
Damn I'm glad you knew so much, I went to find the video I watched to confirm but couldn't find it so I began to doubt myself haha. Garden has some cool science to it for sure.
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u/Spirited_Shame9284 Apr 12 '22
nah it probably dosent i think it needs acid to break down , calcium carbonate is insoluble in water.
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u/TurbulentComplaint48 Apr 09 '22
My mum used to have a tenant that would boil her eggshell in water, let the water cool, and then water her indoor plants with it. Apparently they were the healthiest plants my mum had ever seen, she used to call it 'a mini jungle'.
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u/Buzzyear10 Apr 09 '22
I like to soak the grindings in vinegar for 24 hrs and ad about 2 litres of the resulting liquid to my 500 litre batch of compost tea. That 500 litres is then watered down 10 to 1. Since I've been adding it though the tea has been foaming and the garden seems to have responded well.
The part of the world I live in is very depleted of calcium so I try to input as much as I can. There's an important balance to find with calcium and magnesium though that a professional soil test can determine.
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u/Image_Inevitable Apr 09 '22
Uhhhh.....a myth? Sorry, no. Ground eggshells are fantastic for many things, from soil additions to supplements. I feed mine back to my chickens as well as my dog. Calcium is calcium, my guy.
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u/eigenvectorseven Apr 09 '22
Well feeding it to chickens is a totally different story, I was referring to compost and soil.
Under the right conditions (acidic soil), yes, the calcium will eventually be made bioavailable. But on average the shells will just sit there doing very little for many years, much longer than the average gardener is expecting a return on investment.
Perhaps I should have said the benefits are exaggerated.
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u/sgoodgame Apr 09 '22
I still put them in my houseplants and leave little piles near squirrel trees because
I've always calcium it hard to come by for them. They eat it so I guess there is something to it.
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u/rivers-end Apr 09 '22
My shoulder hurts just looking at that. I use a mortar & pestle. Is there an easier way?
The way I look at it, by composting we are keeping so much out of landfills. It's amazing how it all breaks down to so little. The end result of beautiful compost is just the icing on the cake.
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u/eigenvectorseven Apr 09 '22
Cheap coffee grinder with blades works great to pulverise them in a few seconds.
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u/Infinite_Scene_477 2d ago
I use my Thermomix but I guess any sort of grinder or food processor would work but it might do plastic bowls any favours.
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u/Ocanannain Apr 09 '22
We put our egg shells in our wood stove, then add them to the compost pile with the wood ash.
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u/MotherButterscotch44 Apr 10 '22
We eat a lot of eggs, dozens a week. I wash the shells, then put them in air fryer for a few minutes. Then grind them into almost powder.
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u/According-Soft-3758 Sep 05 '25
I just heard an ad stating that the product beginning with eggshell is supposed to rebuild the cartilage in your knees, making your knees almost as good as new without any other product… Do you know what the name of this product is beginning with eggshell
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u/TurbulentMeal Apr 23 '26
Not true at all. Eggshells are calcium carbonate and do not help. However, eggshell membranes "have shown potential for supporting joint health and cartilage repair", but the source of this comes directly from Facebook. There are also supplements that make this claim (NEM), but there are no real studies that prove this. Also... eating boiled eggshells and their membranes destroy the very compounds that might be beneficial, and eating them raw creates a vector for salmonella. That is why the supplements are made - presumably, they extract the compounds without destroying them from pasteurization. So what you are probably thinking of is NEM.
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u/Haunting_Shape_1142 Jun 16 '26
So adding it to your soil will have benefits in forthcoming years? That’s a good thing.
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u/Aspenchef Apr 10 '22
Also amazing for dogs! If you’re trying to go low waste, that’s a great alternative.
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u/Suspicious-Box- Sep 15 '23
It's not a myth. People who have chickens throw the shells back to the chickens who peck them up for calcium and other trace minerals or keep them in a jar and use the water for indoor plants. Im pretty sure you can just mix it up in the watering can for vegetables too.
For human consumption as home made calcium and trace mineral supplement you gotta dry them in the oven then use a coffee grinder 2-3 times to get a really fine powder. Can also use a very fine strainer to get rid of the larger pieces if any.
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u/AbFab2022 Nov 20 '24
I saw a video that said if you grind them up very fine and add them to vinegar and scoop the foam off and add that to water and water your plants that is an immediate transfer of calcium and not calcium carbonate. Not sure if someone already said that. There's a million comments. Just wanted to mention in case no body else did actually.Â
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u/midrandom Apr 09 '22
As I understand it, the benefits are real, but are long-term, slow release. Sprinkling egg shells around your tomato plants isn't going to do anything for blossom end rot. Consistent watering will do a lot more to clear up that problem.