Eggshells are the one material that can be confusing if you are new to composting. Because it’s an animal product, but not quite meat, it leaves many people wondering Can you compost eggshells? or Can eggshells be composted? and the truth is, yes you can.
You should compost your eggshells. Eggshells are a natural source of calcium. This calcium when added to the soil can help regulate soil pH. Calcium is also important for plants to develop healthy fruits. Blossom end rot in tomatoes is a sign of either a calcium deficiency, a pH imbalance in the soil or both.
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How long do eggshells take to compost
Composting Eggshells can take years to compost if it’s thrown in the compost pile. If you convert your eggshells to a powdered form they will compost in about a month.
The key to getting the eggshells to break down in your compost quickly is to give the bacteria as much surface area as possible to work on. While you could do a decent job of crushing them with a rolling pin, I turn my eggshells into a calcium powder. This gives my microbes greater surface area and it’s easy to use in the compost bin and around the garden. For step by step instructions on how to crush eggshells for compost please check out this article.
Can you put eggshells in compost?
Yes, you can put eggshells in compost piles. If you are doing a passive/ cold composting system then you can put them after crushing it by hand. However, if you would like to use your compost within 2 months some preparation is necessary.
How to prepare eggshells for compost
The first thing you need to do is clean your eggshells. The inside of eggs can also harbour bacteria like salmonella. Because home composting systems don’t get as hot as commercial composting systems this step is highly recommended. If your compost pile doesn’t get hot enough it won’t kill off the bacteria and you can end up transferring the unwanted bacteria to your soil.
If you are wondering how to clean your eggshells for compost, it’s a pretty simple process. Before using your eggshells for compost you should rinse them in warm water.
After you’ve cleaned your eggshells you can bake your eggshells in the oven for about an hour on low heat. Baking the eggshells is an extra step to kill off bacteria but I also like it because of the consistency of the final product. Without baking, I find the eggshells can come out like a thick paste rather than the fine powdery grains I prefer. After you crush or grind the eggshells with whatever you have available and that’s it. Your eggshells are ready for either the compost pile or can be added directly to your soil.
Why are eggshells good for compost?
Yes, eggshells are good for compost systems. Although eggshells are almost entirely made up of calcium, that calcium isn’t in a form that plants can use. By adding it to your compost pile the beneficial microbes in the compost pile can break down the calcium into a form available to plants.
Do worms like eggshells?
Worms love eggshells. If you are using eggshells in your worm bins you should grind it to the consistency of a fine powder.
Earthworms will consume the powder and use it as grit in their gizzard to help them break down their food.
Eggshells can also help regulate the pH of your worm bin. If you can, add a handful when starting your bin or a few tablespoons when adding food for your worms. This will give you an extra layer of protection if your food becomes acidic as it starts breaking down in the worm bin.
Can I add eggshells directly to the soil?
You can add the eggshell powder directly to the soil. The bacteria in the soil will break it down over time.
Applying eggshells to the soil in this way is more of a preventative method. If your plants are showing signs of calcium deficiency adding eggshells after the fact probably won’t make a difference. In most circumstances, the eggshells won’t break down fast enough from their current form (Calcium Carbonate) to a form that is usable by the plant.
Adding eggshells before planting
Adding eggshell powder before planting things like tomatoes and cucumbers is a good practice. Just add a few tablespoons to the planting hole before you transplant is all you need. By the time the plant starts to flower the microbes in the soil would have done their job.
As a bonus, I add more eggshell powder when the plant starts to flower. Some plants can bear fruit for several months. This ensures there will be an adequate supply of calcium while the plant is in its fruiting phase.
How to make calcium immediately available to your plants
If you are absolutely sure you have a calcium deficiency and you need to correct it immediately you can fix it with a few common household items.
Mix equal parts crushed eggshells and vinegar by weight. Your mixture will begin to fizz. This happens because the acid in the vinegar reacts with the calcium carbonate in the eggshells. The result is the carbonate being released as carbon dioxide and the calcium remaining as calcium ions in the mixture.
Set the mixture aside for about 3 hours before using it.
To use it in the garden dilute the mixture with 10 parts water to one part mixture. It can be used on your plants as a foliar spray or as a soil drench. When using homemade remedies like these on your plants it’s always good practice to test a small area first before spraying the entire plant.
Final Thoughts
Getting into the habit of saving your eggshells and using them in the garden long term can pay off. They are free and they can be very beneficial to the health of your soil. However, having a calcium deficiency in your plants doesn’t always mean that there is a calcium deficiency in your soil. In most cases, there is some other factor affecting the efficient uptake of calcium from your soil.
Eggshells can also be used as a deterrent to slugs and snails in the garden. However, you would need a lot of eggshells to be effective. If you don’t eat eggs, or if you don’t eat enough eggs at home consider asking your friends and neighbours to save theirs for you. Or, if you have a large enough garden you can get a consistent supply from a local bakery or restaurant in your area.
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