You can add them any time. They take quite awhile to become decomposed.

Don't dig ground when frozen or wet. Also if you plant to keep adding eggshells indefinitely you should sample your soil and have it analyzed to see if there is a need for what minerals they provide. You may be bothering with this for nothing or could even end up eventually causing an excess of something.

Depends on why you are doing it. For nutrients - they take months and months and months to decompose and even then they don't provide much in the form that plants can use. Much more effective supplements are readily available. On the other hand they can be somewhat effective against slugs and snails right off the bat.

Dave

Digdirt2, you are absolutely right about the slugs and snails. We have been putting eggshells in the garden for slug and snail prevention for over 10 years now. The vegetables are thriving, and there are no snails or slugs to be seen anywhere.

Lea, our folks in Central Missouri and Southern Iowa put eggshells out until the first snow, and then save them in a 5 gal. bucket until March. I don't know of anyone else in that area who puts eggshells out during the winter. Our gardens in Zones 7-9 (Central Alabama and Northern Florida) put eggshells around the plants year round.

You know, I throw eggshells in my compost pile, and six months later, they're still there. Eggshells are rocks that come out of birds and reptiles. If you want calcium in your bed, crushed limestone is a much easier way to get it. Sure, throw 'em in, but they aren't much better nutrients than other rocks.

With regard to slugs and snails, eggshells when crushed can be used as a barrier. Eggshells mixed in with soil aren't going to scare them off.

I should add that I sit on limestone, and so soil calcium deficiency is never an issue for me. But eggshells are actually a pretty poor way to add calcium to soil. It occurs to me that blackboard chalk would be terrific for doing that. Unlike eggshells and limestone, it's a compressed powder, and when it hits moisture, it will fall apart into calcium carbonate (and, to the extent blackboard chalk is increasingly made of gypsum, calcium sulfate) powder. That powder/dust is easily degraded by soil acids -- much more easily than eggshells will be degraded, and ionic calcium quickly results, which is an available form of the nutrient. Gypsum itself is pretty soluble just in plain water. Blackboard chalk is dirt cheap, as well. We can call them calcium spikes.

Speaking of dirt cheap, if you use drywall (which is mostly gypsum), it'll have the same effect. I've heard that recycled drywall board is a wonderful compost amendment in places with calcium and sulfur deficiencies.

If calcium is a problem for you, don't waste your time with eggshells.

Lea, what is your reasoning for adding the eggshells? Knowing what you are trying to achieve would help people advise. Personally I have found they have no effect on slugs and snails but I do live in a moist climate with a huge gastropod population. I just add my egg shells to the compost heap, as I do any organic kitchen waste.

Thanks everyone for their views. I had heard that it was good for the soil plus the slug issues. I don't even know if I have slugs or snails. We don't get garbage pickup, live in rural area plus we don't use our garbage disposal so I just thought would be a good place to dispose of them. I grind them in my blender and scatter them around my hostas and tomatoe plants. I just was wondering if it would be ok to put them out during the winter. We have a large garden area plus I have a compost pile. We will check our soil next Spring and see if that tells us anything. It is pretty healthy dirt.

Again, kitchen eggshells are rocks that come out of chickens. You can put rocks in your garden in the summer or winter. The soil won't care. If this is about disposal of eggshells, then just throw them on the ground or on the compost pile. They won't compost, but will very slowly decompose there, as they would just laying on the ground. If your soil is calcium poor (few soils are), then eggshells will help in the VERY VERY long run.

All my eggshells go on the compost heap and I do not find they hang around long. Certainly the garden isn't covered in eggshells. I don't grind them because I try not to waste electricity. A crush in the hand is ample.

As a source of calcium carbonate egg shells are a valuable addition to the soil in the garden.

The garden is a fine place to throw eggshells, if you don't want to clutter up your garbage with them. But in most cases, they won't do a lot of good there. They appear to disappear, because they are getting dyed the color of the soil. But they're really there. Most soils do not need calcium. If soil has plenty of calcium, adding more doesn't do any good.

I knew a guy who took four vitamin tablets every day. Why? Because if you needed vitamins, he said, taking more than the required amount must make you a lot better!

They eventually get absorbed in the soil. But one thing I read (maybe Mother Earth???) was that if you have cabbage moths (the pretty little white fluttery things) and you toss some egg shells out among your fall/winter crops, they feel threatened by the white shells, thinking they are other cabbage moths that got there first! And are scared away!

Either way, I doubt it's going to hurt any thing! Nancy

You know, only a small fraction of the country - many locales in the southeast, have seriously low soil calcium that requires remediation. Do a soil test to be sure. But it turns out that the USDA has established that only about 30% of Americans are getting the recommended amount of calcium in their diet. So hey! Take your eggshells and dissolve them in some vinegar - it'll take a week or so. Use that vinegar in your salad dressings, and presto, you're likely doing yourself some real nutritional good. Don't waste it on soil that already has plenty. Yes, you could even do the same thing with blackboard chalk.

Your advices daninthedirt are quite unconventional. I remember in one of your previous posts somewhere you advised to use dish washing liquid to spray plants! Thank you, I would rather have beneficial insects to do the job, and eat only egg whites and yolks (without much vinegar) leaving the shells for the soil organisms to decompose. Good luck with your diet!

We're not talking unconventionality. We're talking simple chemistry. Egg shells degrade VERY slowly in soil. If your soil has a serious calcium deficiency, egg shells are a poor way to fix it. If your soil is not calcium deficient, they're just rocks. Soil organisms do not decompose eggshells. It's the acidity in the soil that does it, as long as we're talking simple chemistry. (And FWIW, decomposition of organics by soil organisms is not a strong source of soil acids). As noted, it's not going to hurt to put eggshells in your soil, but it's also not going to help much.

Using a tablespoon of dishwashing liquid per gallon of liquid is a standard wetting agent for waxy foliage, and is a recognized approach to mitigating small insects. If you're going to criticize my posts, then do it right.

@Lonejack

I haven't read the whole thread, but I just wanted to say that eggshells decompose very fast in my garden (say about 1 to 3 weeks [for them to no longer be visible to the human eye]) as long as they're crushed, mixed with the soil, and buried. I'm not trying to say whether it's a good idea to add them, but I don't have a problem with it personally.

I was pretty surprised by how quickly they disappeared. It was pretty much just as fast as vegetable scraps I mixed with soil and buried.

I don't know what would result in a different soil. The soil I'm talking about was something like clay loam with decomposed organic matter. As for the crushing, I just crushed them with a shovel while on the soil surface and stirred them in (they were still highly visible at that point). They had been in partial sun on the soil surface for some days and weeks before I started. I mixed in vegetable scraps with them (e.g. moldy melon rinds and squash; probably some grain and other stuff). I could be wrong, but I don't think our soil was calcium deficient. We just didn't want to waste the eggshells. Eggshells do have other minerals besides calcium, though. I'm not sure what their pH is.

When it comes to compost bins, I think eggshells do take longer to visibly vanish in those, though (although I tend to think adding soil would speed up decomposition).

@daninthedirt I started this post before I saw yours; I'm not trying to be contrary. By decompose, I'm not attempting to say they were or were not broken down by soil microbes, but I'm personally not convinced that soil microbes won't actively seek to utilize the eggshells.

Soil microbes don't eat rocks. Eggshells are rocks.

Well, let me be more specific. It has been understood very recently that certain microbes can digest sulfide-bearing rocks, causing serious environmental pollution from the heavy metals that those rocks contain. Eggshells are mainly calcium carbonate = limestone. I suppose microbes with indigestion and acid stomach might like that, however!

Dan is correct. Soil microbiology has no effect on eggshells and does not help to decompose them. Adding finely crushed or powdered eggshells to an acidic soil can release the calcium and other nutrients as it is the acidity that actually breaks down the chemical composition of the shell. If you do not have moderately acidic soil.....and fail to break the shells up sufficiently........then they will do nothing.

It has been posited that the appearance that eggshells are decomposed when added to compost or just the garden soil is really just the physical act of working the soil (or turning the compost) that breaks the shells into finer and finer pieces to the extent that they just "disappear" into the soil.

@daninthedirt, wrong, microbes do indeed eat rocks.

@Lea Grabb, yes put them in the garden during winter, no matter what the arguments are about eggshells, but for the simple fact of keeping them out of the landfills is all the reason you need.

FWIW, earthworms do not have teeth and need the help of grit in their gizzards to help digest what they eat (just like birds). Minute particles of eggshells are an ideal form of grit, especially when one is vermicomposting. If one has worms in the garden and if the eggshells are in small enough particles they will still get broken down in alkaline soils. Not as fast as in an acidic soil but they will disappear eventually.

Rodney

sqwib, I think you may need to take another look a your sources :-) Microbes do not "eat" rocks - they only consume and digest organic matter. But they can and do assist with biological weathering, where they release chemicals that will help to particlize and breakdown the rock surface into its chemical elements.

Um, you need to keep eggshells out of the landfill? Why, pray tell, would you need to do that? You don't want to throw rocks into landfills?

I don't think earthworms contribute much to chemical breakdown of eggshells. Their gut pH is right around 7. That won't do it. Might make the pieces smaller, but won't turn calcium carbonate into calcium. Besides, unless you are vermiposting, not a lot of your soil will end up going through them.

I agree that the way that eggshells "disappear" in soil is that they get chopped up and discolored. But that doesn't break them down chemically. If I wash and bleach my compost, I can find loads of itty bitty white pieces of eggshell.

Your gardening practices are quite unusual daninthedirt, may be it is why your experience about the egg shells is different, as well. In my natural, organic garden egg shells break down (i avoid using the world "decompose" here) very quickly. It looks like the same happens in the gardens of other people posting here.

BTW I wonder why YOU put the egg shells in your compost instead of taking them to the landfill?

I'm agreeing with others here, windberry. What may seem unusual to you is not to others. Yep, I can "break down" eggshells too. A hammer and a rolling pin work wonders. But I won't get calcium out of them that way. If you keep your eyes closed, you can see anything you want.

Why do I put them in my compost? Because they come from my kitchen, and I might as well send them where everything else goes. But as they turn to small mineral particles, they enhance the friability of the soil. So they do contribute. I also add perlite, vermiculite, and mineral grit from the creek to my mixes for the same reason. I don't add them for calcium. I'm sitting on limestone, so adding calcium as a fertilizer would be funny.

"Your gardening practices are quite unusual daninthedirt"

I've been reading Dan's posts long enough (years!!) on this and other forum to determine that his practices are pretty straightforward and SOP for composting and preparing garden beds......not at all unusual :-)

'Breaking down' is just the right terminology to use! With any soil activity or turning of compost the eggshells break into smaller and smaller pieces. But they don't decompose like vegetative matter would. And that is what's happening as well in other peoples' gardens that assume the shells are decomposing when in fact they are just getting ground up into smaller pieces.

btw, a well-tended compost pile will go through a period of highly acidic conditions that can help with the decomposition or degradation of the shells.....provided they are of a small enough particle size to start with. Much easier to accomplish with a commercial operation than a home compost pile. And that's also where kitchen and yard waste are processed in my area if not addressed by home composting - a commercial composting operation, NOT the landfill!!

Dan- The overall ph of an earthworm's gut is right around neutral. However, individual ingredients that are eaten are not. Most raw organic matter tends to be slightly acidic and let's not forget about the humic acids present in composted soils. In order for these to be neutralized something basic must be used, i.e. calcium carbonate.

I can only speak of my own garden but at certain times of the year, usually in early spring after the fall addition of raw organic matter, my garden beds are teeming with earthworms. If one's garden is similar to mine then there is a massive amount of organic matter and soil going through worms.

Rodney

I don't think it would be a waste.

Rodney, those humic acids (and carbonic acid as well) are all around eggshells in a compost pile. Eggshells don't need to go through a worm gut to be exposed to those. But those are VERY weak acids, and won't be very effective in dissolving eggshells. That is, in fact, how the eggshells do dissolve, via soil acids, but it takes a LOOOONG time for that to happen. What we're trying to say is that eggshells look like they are dissolving, because they disappear, but that's not why they disappear.

Worms do a lot of great work in breaking down tough organics. It's not by chewing. Worms produce a wonderful molecule called drilodefensins that allow them to withstand chemicals in organics that would poison many other digestive creatures. In my own neighborhood, oak leaves are rich in tannic acids and other polyphenols that are poisonous, but the drilodefensins allow worms to eat these leaves happily. Oak leaves are a major part of my compost, so I am indebted to worms for the job that they do.

Daninthedirt, dont twist my words, I never said "You need to keep them out of a landfill"! It's my choice to recycle them in my own garden and if someone asks if it's a waste to put it in the garden, I say NO, and putting all arguments aside, I feel better tossing eggshells in my garden beds and not the trash. Also good point about the friability of the soil, so why compare them to rocks?

Thank you gardengal yes as you stated microbes do eat rocks!

"Thank you gardengal yes as you stated microbes do eat rocks!"

Reread my post again. That is NOT what I said!!

Gardengal, Sure it is.

No it is not!! Biological weathering is not at all the same as consumption and digestion. Check your dictionary for a definition of 'eat'.

"Daninthedirt, dont twist my words, I never said "You need to keep them out of a landfill"

More rereading required, and misquotes are not appreciated. What I asked (it was a question) was "Um, you need to keep eggshells out of the landfill? Why, pray tell, would you need to do that?" The answer to that question still isn't quite clear. You said "the simple fact of keeping them out of the landfills is all the reason you need." Pardon me if I misinterpreted, but it sounded like you were saying that that you considered it important to keep eggshells out of the landfill. I'm just saying that I can't imagine why. You're welcome to explain to me why eggshells are bad for landfills. In my part of the world, landfills are done in a big hole excavated in a bed of calcium carbonate. Throwing itsy bitsy pieces of calcium carbonate back in the hole would seem to be of little concern.

Yep, they eat rocks!

Copy/paste

Microbial activity breaks down rock minerals by altering the rock’s chemical composition, thus making it more susceptible to weathering. One example of microbial activity is lichen; lichen is fungi and algae, living together in a symbiotic relationship. Fungi release chemicals that break down rock minerals; the minerals thus released from rock are consumed by the algae. As this process continues, holes and gaps continue to develop on the rock, exposing the rock further to physical and chemical weathering.

Please show me where in that statement it says that soil microbes eat rock. Lichens are not soil microbes - they are complex organisms that are more related to plants than anything else in that they create their own food via photosynthesis. And they don't eat rocks!!

"When growing on mineral surfaces, some lichens slowly decompose their substrate by chemically degrading and physically disrupting the minerals, contributing to the process of weathering by which rocks are gradually turned into soil." This is biological weathering......not eating. Slowly is the key word here....the process of biological weathering takes eons to achieve. And really has no bearing on the question at hand anyway.

You are really just picking nits!!

keyword here consumed...

You are the one Picking nits, I dont get why you are arguing this, the dam things break down the minerals in rocks and are consumed by a microbe...(algae)

they eat rocks!

copy/paste

Microbial activity breaks down rock minerals by altering the rock’s chemical composition, thus making it more susceptible to weathering. One example of microbial activity is lichen; lichen is fungi and algae, living together in a symbiotic relationship. Fungi release chemicals that break down rock minerals; the minerals thus released from rock are consumed by the algae. As this process continues, holes and gaps continue to develop on the rock, exposing the rock further to physical and chemical weathering.

microorganisms. A very small living organism visible with a microscope is called a microorganism, or a microbe. Microbes include viruses, bacteria, archaea, fungi, plants like algae, and protozoa, among others

A lichen is a combination of two organisms, a green alga or cyanobacterium and an ascomycete fungus, living in a symbiotic relationship. Whereas algae normally grow only in aquatic or extremely moist environments, lichens can potentially be found on almost any surface (especially rocks) or as epiphytes (meaning that they grow on other plants).

My soil doesn't have any algae in it. But maybe you're doing hydroponic gardening, and yours does? That would be cool to see your algae breaking down rocks in your hydroponic garden. Send pix!

Fungi and lichens largely break rocks into smaller rocks. That's called physical-biological weathering. They turn rocks into soil. Tree roots do it too. You don't get any nutrients released that way. Chemical-biological weathering is done by acids that are released by fungi and bacteria. Those acids do dissolve the carbonates and liberate calcium ions. But as we keep saying, over and over, those acids are weak, and it takes many many years for it to happen. I guess if you're sufficiently forward looking, you could use your eggshells to provide calcium to your plants in the next decade! But if my soil lacked calcium, I'd want to fix it faster. In neither case are fungi or lichens "eating" rocks.

The word "consume" is ambiguous here. Look it up. Merriam Webster says, of the transitive verb "consume", one definition is "to do away with completely : DESTROY as in Fire consumed several buildings." So fire ate some buildings? Who knew? Burp ...

My rock floor is calcium carbonate (as in, eggshells). It's limestone. If my soil creatures ate limestone or even dissolved much of it, my rock floor would disappear. Ain't happening.

Sure, put the eggshells in soil. But unless you use a whole lotta eggs, it isn't going to do much for your soil structure. I was NEVER trying to discourage anyone from recycling anything. Just trying to convince them that putting eggshells in your garden didn't do much for your garden if you did. If you get pleasure out of putting eggshells in gardens, by all means do it! I call eggshells-in-gardens theraputic gardening. It does more for the gardener than it does for the garden.

I don't do nits. Just facts. The OP wanted to know if something was a waste of time. This sure is.