10 Reasons to Stop Throwing Away Your Eggshells
Eggshells can be reused in many ways that don’t readily come to mind. Check out these innovative ideas for your home, garden, and more!
Eggshell Uses at a Glance
- Garden: calcium for tomatoes and peppers, slug and snail barrier, cat-litter-box deterrent, seed-starter cups.
- Kitchen / pantry: drop a crushed shell into ground coffee to soften bitterness; camp scrub for greasy pots.
- Body / health: bake clean shells 350°F for 8 min, grind to powder, use as a folk calcium supplement (check with a doctor first).
- Pets and birds: sterilized shells crushed into wild-bird and chicken feed; a vet-approved pinch in dog food.
- Around the house: textured paint mix, sink-strainer scrubber, drain cleaner.
- Sterilize first: always rinse and bake (250°F, 30 min) before eating, feeding pets, or grinding to powder, to kill salmonella.
Statistics say the average American consumes 250 eggs per year. Remember, we’re not just eating two at a time, sunny-side-up, we’re using them in homemade baked goods, batters, main dishes, and more. And if you think the only two solutions for all those eggshells are the trash or composting pile, you may want to think again.
According to the Encyclopaedia Britannica, a chicken eggshell is about 95 percent calcium carbonate (the same mineral as cuttlebone and limestone), plus small amounts of magnesium, phosphorus, potassium, and trace minerals. That makes the shell the most useful “waste” leaving your kitchen this week, if you know what to do with it.
Reuse Them!
In the age of recycling, eggshells, nature’s suit of armor and an excellent source of calcium and minerals, can be reused in many ways that don’t readily come to mind. Enterprising consumers can make the best of what most would consider a highly disposable item.
Top 10 Uses for Eggshells
These ideas can help you raise your eggshell IQ. In all cases, except where specified, eggshells should be crushed, made either coarse or fine, depending on the use:
- Use eggshells as a calcium- and mineral-rich additive to wild bird feed and chicken feed.
- Add them to ground coffee before brewing. The shells help reduce any bitterness. Wash the shells thoroughly to remove any egg residue, dry, then crush and add to your ground coffee.
- As a soil additive for houseplants, they add minerals and help keep soil loose and aerated.
- Love camping? Use those shells with soapy water as a natural abrasive for pots and pans, especially when cleaning products and really hot water are at a premium.
- Bake clean eggshells at 350 degrees for 8 minutes. Let cool and grind to a fine powder. Add as a calcium supplement (a teaspoonful does it) to juice, smoothies, etc.
- Add to your garden to keep cats away that may be using it as a litter box. Cats will not like the sharpness under their tender paws. Their smell can also reportedly deter deer and repel slugs, snails, and cutworms without resorting to toxic chemicals. Maybe tantamount to that, mineral-charged eggshells can be crushed and scattered into each hole before planting. Sprinkle additional crushed shells around your plants every couple of weeks. Use them to start your seedlings. Here’s how.
- Skin irritations? Folklore tells us to drop an eggshell into some apple cider vinegar for a couple of days. Apply to skin irritations or itches.
- Unclog drains: Placed in your sink strainer, they can trap errant solids. When they ultimately break down, they will serve to clean pipes on their way out.
- Doggie defense: Dry eggshells in a 250-degree F oven for 30 minutes. Place in plastic bag and roll/crush with a rolling pin to a fine powder. Add to dog food as a calcium supplement (be sure to check with your vet for the proper amount).
- Looking for a fun art project? Crush and add to paint for decorative textured walls or furniture.
Crush Size by Use, A Quick Map
| Use | Crush size | Sterilize? |
|---|---|---|
| Coffee bitterness fix | Coarse, 1 to 3 mm | Rinse, dry |
| Camp pot scrub | Coarse | Not required |
| Garden slug / snail barrier | Coarse, sharp pieces | Not required |
| Tomato calcium boost | Fine to medium | Optional |
| Seed-starter cups | Whole half-shells, rinsed | Rinse only |
| Human calcium powder | Powder fine | Bake 350°F, 8 min |
| Dog calcium supplement | Powder fine | Bake 250°F, 30 min |
| Wild bird / chicken feed | Medium | Bake 250°F, 20 min |
| Textured paint | Medium | Rinse, dry |
| Sink strainer / drain | Coarse | Not required |
Two Easy “How To” Notes
- To sterilize for eating or feeding pets: rinse the inside of the shell under cool water, lay on a baking sheet, bake at 250°F for 30 minutes. Cool and grind in a clean coffee grinder or with a rolling pin until you have a fine powder.
- To make seed-starter cups: save whole half-shells (a clean break around the middle works best). Rinse, dry, set in an egg carton, fill with seed mix, plant one or two seeds. When the seedling is ready to transplant, crack the shell lightly and plant the whole cup, the shell breaks down in the soil and feeds the roots.
Time Eggshell Seed-Starting to the Last Frost
Start seedlings 6 to 8 weeks before your average last frost. See your region’s long-range outlook to time it right.
See Your Extended ForecastFrequently Asked Questions About Reusing Eggshells
Are eggshells actually a good calcium supplement?
Properly sterilized and ground to fine powder, yes. Eggshells are about 95 percent calcium carbonate, the same form found in commercial supplements. A teaspoon contains roughly 800 to 1,000 mg of elemental calcium. Talk to your doctor or vet before regular dosing.
Do eggshells really keep cats out of the garden?
The sharp edges deter many cats from settling in to dig. It is not a perfect barrier, especially for determined cats, but for casual visitors it works as well as commercial granules and costs nothing.
Why add eggshells to coffee?
The calcium carbonate in eggshell is mildly alkaline and binds with some of the acidic bitter compounds in coffee, smoothing the cup. Scandinavian “egg coffee” relies on whole egg and shell stirred into the grounds before brewing.
Are there risks to using raw eggshells?
Yes, salmonella. Always rinse and bake shells (250°F, 30 minutes) before grinding to powder for eating or feeding pets. Garden uses, paint additives, and drain-strainer uses do not require sterilization.
How fast do eggshells break down in soil?
Slowly. Crushed shells take 6 to 12 months to fully decompose in compost or garden beds. Powdered shells release calcium in weeks. Both work for next season’s tomato beds, but if you need a quick fix for blossom-end rot, use powder.
Can I give eggshells to my chickens?
Yes, with one caveat: bake and crush so the shells do not look like eggs. Whole or large pieces can trigger an egg-eating habit that is hard to break. A clean grind into the layer feed is the safe form.
Will eggshells in the drain really keep the pipes clean?
The folk-wisdom claim is overstated. The shells trap larger solids in the strainer, which is genuinely useful. They do not scour pipe walls. For real pipe cleaning, hot water and baking soda + vinegar work better.
Share with us your ideas for eggshells.
For more kitchen-thrift reading, see don’t toss those peelings, smart uses for used coffee grounds, and 10 uses for disposable chopsticks.
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Beth Herman
Beth Herman is a freelance writer with interests in healthy living and food, family, animal welfare, architecture and design, religion, and yoga. She writes for a variety of national and regional publications, institutions, and websites.
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If you have a pot that is black on the bottom, use eggshells and ketchup to clean the black stuff off. It works great.
I would like to join the discussion
I don’t love the “use them to scrub while camping” idea. It seems to me that would result in broken pieces of shell littering our pristine public lands. Pack it out.
you seriously think that broken pieces of egg shells are “littering”; google will help you learn more about eggshells and how great they are for our enviroment
I always leave the egg shells and coffee grounds on the ground when camping. It is great for the soil. Both are used for gardening as well.
First learning about egg shells.Thanks
Me too. So interesting.
Thanks for the information on eggshells.
Be sure to use only farm fresh eggs from chicken fed on an organic diet. No one wants to spread the chemical rot of the “gardening industry” to our own, homegrown food supplies.
As a child on a farm, we gently used a knife to break the shell in a round hole, lifted out the piece, shook out the egg, rinsed the shell well, dried it. Then we used finger nail scissors to cut the edges smooth, painted the outside and sprinkled with glitter. Then we found small photos or cut out small pics from Christmas cards, etc. & glued inside the egg. Then we cut saran wrap to fit, used airplane glue and stretched to wrap tightly until it dried so it made a window. When dry, we trimmed it and decorated the edges with sequins, putting a string on top to hang as an ornament on the Christmas tree! I still have a few! We even made some from duck eggs later in life. Very pretty and fun to make.
Share a picture of the decorated eggs, please.
I broke up shells and glued to wooden box and lacquered. I made this when I was 16 and 74 now and still have this box.
That’s awesome! I’d love to see a picture of that:)
Thanks for all the awesome ideas! I’ve been placing these around plants for years and to help deter slugs from eating my hostas and strawberries. I didn’t know you could pour the water from boiling eggs on weeds! I will be trying this for sure. I do, however, put a teaspoon of salt in my water when I boil eggs, I guess this should still be ok to pour over weeds, but I would not suggest doing this in a flower bed, because salt will most likely kill the good plants too.
Believe it or not. Just for your plan Epsom salt real good. you should do me a favor and Google it, and see what you think
Awesome ideas, many I use, many more to add to my list. I use a mortar an pestle to grind my shells. Never knew about the sterilization technique to add to drinks, or for dogs!