Using Eggshells in the Garden

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Grinding eggshells to add calcium to garden soil

Holidays have a way of dredging up old memories, for example my Swedish grandmother's method of putting a dried, crushed eggshell into her old percolator along with the coffee grounds. My grandmother's people came from the north of Sweden where nothing is wasted, but did putting eggshells in the coffee make it better?

Actually, it probably did. Eggshells are made up of primarily of calcium, which readily leaches into warm, acidic liquids like coffee, which has a pH between 4 and 5. Like a low dose of lime, the eggshells probably raised the pH slightly and mellowed its flavour. They also probably enriched the coffee with dietary calcium, which Grandma Ruth would have loved had she known about it.

Indeed, recent research has shown that consuming eggshell powder as a dietary supplement increases the formation of both cartilage and bone in people with osteoporosis, and can significantly strengthen bones of post-menopausal women.

Eggshells used to deter slugs

Using Eggshells in the Garden

The calcium from eggshells is also welcome in garden soil, where it moderates soil acidity while providing nutrients for plants. Eggshells contain such an abundance of calcium that they can be used almost like lime, though you would need a lot of eggshells to make a measurable impact. By the time they are well ground, it takes 150 eggshells to make a cup of coarse eggshell powder. I should know. I make precious pulverised eggshells and use them as a dietary supplement for selected plants. Tomatoes that have a handful of eggshell meal worked into the planting site are not likely to develop blossom end rot, and plenty of soil calcium reduces tip burn in cabbage, too.

I have heard ten thousand times that eggshells placed on the soil's surface deter slugs, but when I tried it the slugs just laughed. When some Oregon slug slayers set up two actual tests, they found that a ring of eggshells stimulated slug feeding rather than stopping it (see photo at right). It is a myth that eggshells deter slugs.

Yet eggshells are quite useful in adding calcium to homemade fertilisers, or you can simply make calcium water by steeping dried eggshells in water for a couple of days, and then using the strained water for your plants, including houseplants. Plants that haven't been repotted for some time often perk up quickly when given a good drench of eggshell water.

Eggs for using in the garden

Clean Eggshells are Safe Eggshells

Eggs are known carriers of salmonella, which should not be present on uncracked eggs that have been well washed, but you never know. Unless the only place the eggshells are going is into the compost bucket, I rinse them well and let them dry in a sunny windowsill.

The dryness should kill any salmonella present, but if you want to store ground eggshells that are safe for you or your dogs to eat (eggshell powder is used as a calcium supplement for dogs, too), sterilise them in a 200°F (93°C) oven for 30 minutes. You can then pulverise the dried eggshells using a mortar and pestle, or let a coffee grinder do the work for you. Stored in an airtight container, crushed eggshells will probably last forever.

By Barbara Pleasant

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"I sterilise and crush my eggs and add to the chicken feed which gives them added calcium for healthy future egg production! "
Krafty Kim on Friday 6 December 2013
"I grind mine in a coffee grinder and then add it with my kitchen waste to my "worm farm" for them to give me vermicompost. I read that worms have a gizzard in their digestive system similar to that in chickens. They need a gritty element to their diet in order to gring and macerate their food. As you note it also tends to offset the coffee grounds low pH which I also feed to my worms. Makes brilliant compost!"
Chris GREENHALL on Friday 6 December 2013
"I freeze all of my kitchen waste, including eggshells, before putting on the compost pile. I have noticed that the frozen eggshells break up into smaller pieces. Freezing also helps break down plant and egg cells which in turn aids in composting. "
Gary Hardin on Friday 6 December 2013
"I save my eggshells to crush and put around tomatoes and other plants. I'm fascinated by the idea of consuming them myself though, as my family has a history of osteoporosis and I'm sure I could use more calcium. How would you grind them fine enough, and what would you use your eggshells in? (Our hens are organic, and I'm assuming salmonella free, since I regularly eat raw cookie dough (YUM!) and haven't gotten sick)"
Joan on Friday 6 December 2013
"OK, Grandpa's secret for amazing plants. Secure Eggshells, Lobster Shells and Shrimp shells from local catering seafood restaurant, freeze them,blend them to a pulp using a liquid mixture of compost tea and Fish emulsion.Depending on soil needs, bone and or blood meal goes into the mix.Imagination can adjust this base recipe. Application can be as a liquid. I mix it with dry finished compost or peat-moss keeping ph in mind when creating. An unnecessary step is to place the tub of mixture in front of a blowing dehydrator to remove all moisture. The end result is a somewhat powdery mix that stores well and can be conveniently hand applied. "
Tee Jay on Friday 6 December 2013
"Joan, the dosage I saw in the two studies above was one capsule dried powder taken twice a day. A coffee grinder should make the powder fine enough to put into capsules. I also have seen people steeping sterilized eggshells in lemon water (one tablespoon lemon juice to one quart water) for a day or so, then drinking the water. I don't see why you could not put coarsely ground eggshells in a tea ball for steeping."
Barbara Pleasant on Saturday 7 December 2013
"Boiling water (as in using eggshells in coffee) should be more than enough to kill any germs. So it's not necessary to sterilize eggshells before using them if it's in something like that. I would imagine that powdered eggshells would be good in all sorts of cooked dishes if someone needed a calcium supplement."
Pat on Tuesday 28 January 2014
"I was using my coffee grinder to grind eggs shells to powder. Finding this time consuming and laborious, plus the egg powder plugged up the lid making it hard to remove, I was trying to figure out an easier way. After much research I purchased the Miracle Electric Grain and Flour Mill - ME300. This mill exceeded my expectation. I was very pleased to see that the opening to the auger was fairly large. I didn’t have to crush the egg shells down to grain size. I filled the hopper three quarters full and the machine easily milled the shells to a fine powder. It did not overheat or plug up. I am raising Red Wiggler worms for the casting to use in my garden. The most effective way for the worms to use eggs shells is to feed in powder form. Now that I have an easy way to grind eggs shells, I will also use them as a soil amendment in my garden and maybe add them to my compost. I also want to mention, I did dry the eggs shells in the over before grinding them. I put the egg shells in the oven after using the oven, and dry them from the residual heat. "
Sherry on Saturday 19 July 2014
"I use my old blender to pulverize my washed egg shells. The base of the blender fits a mason jar perfectly- I put the base (with blade) on my jar full of shells, screw it on, flip it and attach it to the machine. They pulverize nicely dry. I let the dust settle and then I just remove the blender part and screw the mason jar lid on and store it just like that."
Susan Ferri on Sunday 10 August 2014
"I throw my eggshells into an old pie pan that i keep in my oven when my pan gets full I leave them in the oven when it preheats when baking, then I grind them to a powder and am adding them to my plants. I think I will add them to my comfrey tea as well as my coffee grounds"
Terry Obright on Saturday 30 August 2014
"I started adding crushed eggs shells to the soil in my greenhouse borders where i grow tomatoes in 2013, and it was the first time NONE of my tomatoes got blossom end rot. Very successful indeed. "
Andi Fowler on Tuesday 6 January 2015
"Oh my goodness! Incredible article dude! Thank you, However I am experiencing issues with your RSS. I don't understand why I am unable to subscribe to it. Is there anyone else having identical RSS issues? Anyone who knows the solution can you kindly respond? Thanks!!"
Cranswick on Friday 6 February 2015
"It is recognized as a powerhouse as it can produce numerous nutrients essential to the body's normal functioning. There is not any replacement for water, so don't believe you can drink soda instead. There are really many strategies and tips around that you're guaranteed to get confused."
Gurney on Tuesday 10 March 2015
"I have never used egg shells, except to give calcium to the chickens that laid them. I do know if you sprinkle chicken feed a foot away from the plants in a line, the slugs eat it and blow up, or are too fat to move and I feed them to the chickens."
Juanita on Thursday 12 March 2015
"Hi! So I planted some cilantro seeds in eggshells but I hadn't washed the shells!! Now the cilantro is growing really nicely but I'm scared it might be contaminated with salmonella!! I'm really new to all this and I was so excited to just plant the seeds that I went straight to it after cracking the eggs open. Does anyone have any insights? Thanks! "
Aida on Friday 27 March 2015
"The cilantro will outgrow the eggshells in days, maybe hours. Thoroughly dampen the roots, hold the little plant upside down between two fingers, and it should slide out of the shell for moving to a bigger container. If you leave the plant in the shell you will need to crack it, because cilantro has a taproot that wants to go straight down. Better to direct-seed cilantro where you want it to grow."
Barbara Pleasant on Friday 27 March 2015
"I washed my egg shells. then let them dry. then I put them in a blender till they were a powder. my question is I did not put them in oven or micro wave. will this cause a problem .Can I still put them in oven to kill germs? "
Shirley on Monday 4 May 2015
"I have several ziplock bags of crushed eggshells to use in my garden but, did not know about sterilizing them or putting them into the oven. I thought they might help with slugs and deer but after reading some posts, it seems to be countER-productive. Is there som way I can still use my shells in the garden? By the way, I usually let my dogs lick the egg white out and then pull out the "inner skin" of the egg shell which they seem to like very much. Is this a bad thing for them? Susan 5/11/15"
susan on Monday 11 May 2015
"Shirley, it is more dryness than heat that kills the worst bacteria, so your eggshell powder is probably fine...Susan, just add your eggshells to you compost, or dig them right into your soil since they are already crushed. They are a rich source of soil calcium, great for tomatoes. "
Barbara Pleasant on Wednesday 13 May 2015
"How often should you put crushed powered egg shells around your tomatoes? And is it good for all other vegetable plants as well like squash egg plant and peppers? And oh yes hostas. roses dalilies etc."
perry bush on Wednesday 20 May 2015
"How much crushed egg shells is put in the hole when planting tomatoes. "
Shirley on Wednesday 20 May 2015
"Natural soil calcium (decomposing eggshells) is good for all plants, but tomatoes in midsummer have an increased need, so they benefit more than other veggies. One or two handfuls, or about one-quarter cup of crushed eggshells per planting hole for tomatoes or peppers, would be nice. More eggshells crushed onto the soil's surface would not hurt. "
Barbara Pleasant on Thursday 21 May 2015
"Thank you Barbra Pleasant"
perry bush on Thursday 21 May 2015
"I did not add egg shells in the planting hole I just spread it around the plants and worked into the soil. Is that OK?"
perry b bush on Saturday 23 May 2015
"Eggshells on the surface naturally leach their calcium, so it's a good place to put them."
Barbara Pleasant on Monday 25 May 2015
"I am experiencing some small holes and spots on my egg plants. Does anyone have a solution for this problem?"
perry bush on Friday 5 June 2015
"Perry, that is most likely flea beetles. You will need to cover plants with tulle or row cover to limit the damage."
Barbara Pleasant on Friday 5 June 2015
"I live in France and here everyone claims they avoid blight in tomatoes by putting a cover over the stakes they tie them with and spraying with a fermented mixture of plants like stinging nettles, horsetail, chamolille etc. 200g of dries plant for 10 liters of water fermented for 2-3 weeks (when it makes no bubbles it is ready) diluted 1:10 when watering and about the same for spraying the leaves. another advice I got was companion planting with medicinal plants and marigold. So far no blight but I do pick all the leaves with spots on them and throw them in the garbage bin. Hope it helps!"
Lexy on Saturday 6 June 2015
"Lexy I guess we all learn something new every year. And growing vegetable plants presents a new challenges each season.Thanks for your tip."
perry bush on Sunday 7 June 2015
"Ive only just started saving egg shell's so you have provided me with a great read, thank you for that, I have a food garden and also my own chickens so will definately utilise the information in this article."
Kaye Brown on Wednesday 6 July 2016
"Hi. I read that the calcium in egg shells isn't readily available on solid form, needing mixing with vinegar to react and release the Ca. Is this true?"
Mike on Thursday 8 September 2016
"Mike, several studies using eggshell powder as a calcium supplement have showed that bioavailability of the calcium in eggshells is as good as with dairy products, with far fewer contaminants compared to other natural calcium sources. "
Barbara Pleasant on Thursday 8 September 2016
"You said it yourself, "crushed eggshells will probably last forever." Egg shells do not add nutrients to the soil. They do not decompose unless soil is extremely acidic and other conditions are exactly right. They simply break down into smaller bits that are still too big for plants to use. Snails and slugs will crawl right over eggshells. Check the science. "
Kate Russell on Tuesday 5 March 2019
"Kate Russell: That's nice, but you don't seem to have read the article very carefully. Several times she mentioned adding eggshell *powder*, or *pulverized" eggshells to the soil (not, "smaller bits, that are still too big for plants to use"). Apparently pulverized into powder they are quite bioavailable--not to mention other methods of using them (like steeping them in hot water to make "eggshell water", as she mentioned). #AttentionToDetailMatters. Best wishes. :O)"
Fred on Saturday 3 August 2019
"Fred: Yes, I read it. Eggshell powder does work. So does the eggshell water mentioned in the article. My comment was for the majority of people who do not go to that much trouble. Unless the shells are powdered or souped, they will not improve soil. That is all."
Kate Russell on Saturday 3 August 2019
"I am so happy that some agreement has been reached here. "
Barbara Pleasant on Sunday 4 August 2019
"I have only rinsed my eggshells and then dried completely in a bowl on counter- when I have enough I put in a plastic ziplock and use a wooden rolling pin to crush- I get powder and very small pieces- is this crushed enough to use in the garden?"
S erickson on Saturday 28 September 2019
"Yes, S erickson, you are good to go with your soil-ready eggshells."
Barbara Pleasant on Sunday 29 September 2019
"I've been growing parma violets. They are supposed to enjoy calciferous soils, so I have been saving my eggshells and making power. I also have fertilized them and tried adding some bone meal to get them to flower this Fall. I got a few flowers, but not a lot (and the flowers did not occur after adding the bone marrow.) Having already added stuff this season, I am not really sure if I should add extra. Some of the older leaves and leaves that are underneath have turned yellow, but on the whole the plant looks healthy. Is there a good formula for mixing bone meal and eggshell powder with a fertilizer that will help plants that like calciferous organic soil. One site said mushroom compost was the way to go, but it doesn't seem very easy to get a hold of that here in Austin. I just want more flowers than I am getting. I thought the bone meal would take care of that, but it didn't seem to help. Thanks. "
Sheryl on Thursday 12 December 2019
"Sheryl, because you are working with a Mediterranean perennial, it is likely that the plant is resting while the days are short. I would wait until Feb., when days are noticeably longer, to push the plants to bloom. I would expect natural flushes in spring and fall, with little fanfare in between. Both eggshells and bone meal are slow-release calcium/phosphorous sources, great for baseline nutrition, but you may want to drench your plants with a balanced organic liquid plant food when they gear up for new growth in early spring. "
Barbara Pleasant on Thursday 12 December 2019
"Would it be useless to crush the same eggshells into a powder after I have steep the egg shells in hot water to make eggshell water?"
Barbara Rossi on Friday 10 April 2020
"Also has anyone ever heard of putting a whole egg in the bottom of a pot before planting a plant in it?"
Barbara Rossi on Friday 10 April 2020
"Barbara, the calcium in eggshells releases slowly, so they are still of value to the soil after being steeped in hot water. Putting a whole egg at the bottom of a pot will make a mess that will smell awful at some point. Never heard of this method, and don't recommend it."
Barbara Pleasant on Saturday 11 April 2020
"Barbara - the buried whole egg would likely attract critters that would then dig out the plant to get it too."
Debra on Monday 13 April 2020
"I break them up and use them in the bottom of pots for my ivy, palms, and violets, it makes great for great drainage material. I also put them around the wisteria, does it help? No idea but it makes me feel better that I'm not trashing them! "
Trish on Friday 15 May 2020
"I have a climbing rose and this year the sawfly larvae chewed on some of the leaves before the birds and myself picked them off it. So my question is how much ground egg shell should I give to it?? It is about 2-3 feet high. How much should I also use around the Tomato plants and scratch in. I have been saving the egg shells. I know it won't repel the sawfly but it might help strengthen the canes a bit more.."
Karen F on Monday 15 June 2020
"Karen, eggshells release their nutrients so slowly that it's hard to overdo it. A generous handful sprinkled around each plant from time to time would be fine. Good work on the sawflies! Nothing you might have put down on the ground would have affected them because the adult flies are so mobile. "
Barbara Pleasant on Monday 15 June 2020
"I've just gone the lazy route and tossed unwashed eggshells into the kitchen scrap bucket. They make their way into the compost heap. Over the last few years, I can tell where I've added compost to the garden because the soil is full of little chips of eggshell. It breaks down slowly. The shell bits have become my own indicator of where I've already enriched the soil with compost top dressing! Not idea if the eggshells are boosting the fertility, but the compost as a whole has done wonders. "
Maja on Tuesday 14 July 2020
"Should I be removing the thin lining in the eggshell or is that part of the "goodness" for fertilizer? "
Tina on Tuesday 28 July 2020
"Tina, that thin membrane dries into flakes that naturally separate when the eggshells are crumbled into pieces. For use on plants, there is no need to separate it out. "
Barbara Pleasant on Thursday 30 July 2020
"I keep a small cookie sheet in an unused oven and put my egg shells there until its full, then when I am baking something and have taken it out of the oven, i stick the pan of eggshells in and turn off the heat. I fetch them later on when cool. I feel like using uncooked eggshells in the garden could start a bacteria zone, I would not want to get exposed to. "
Jeri Wam on Friday 19 February 2021
"Barbara I’ve read that boiling eggshells to kill potential salmonella destroys the calcium. Is that true? I’m looking for a safe way to remove possible bacteria that retains nutrient values in eggshells for human consumption to support remineralizing tooth enamel. Would washing, drying, then oven baking be sufficient to protect health (before blending into a powder)? How long would eggshell powder be safe to store? Refrigerated? Or in an air-tight jar in a dry place on a shelf? Thanks for your knowledge and wisdom! "
LoreLoreina on Friday 23 July 2021
"I eat the majority of eggs boiled, so that takes care of any salmonella worry. Like some of the above writers, I keep a pie pan on the stove and put the shells in there. They dry in a day or so. When it's full, I use either a smoothie-size blender or a conventional blender. They buzz up in seconds to a nice powder. Super easy and quick. I'm looking forward to using the in the garden next season."
Marjorie on Tuesday 6 December 2022

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