How to Use Eggshells in the Garden and Beyond

By Maureen Wise in Thinking Sustainably

Eggshells that might otherwise get thrown in your kitchen trash can—and end up in a landfill—can be used to benefit both plants and animals in your backyard. How to use eggshells in the garden depends on if you are a veggie gardener, a birder, or a flower gardener. Let's dig into some ways to reuse and repurpose this food waste!

Eggshell Primer

First, know that eggshells don't easily decompose in your backyard compost bin. You need to really smash them into very small pieces in order for them to break down well—but more on that later. Many composters resort to sending their eggshells to the landfill, despite composting much of their other food waste, but think twice before you do!

Eggshells are primarily made up of calcium carbonate. In fact, 95% of the shells are made of this hard, nutrient-rich stuff, according to the University of Florida. You can harvest the calcium from the shells to use as a soil amendment or boost the nutrient content of your birdseed.

Eggy Seedling Starters

I do not have a green thumb. I wish I did! But I love to have a family veggie garden in the summer. If you struggle as I do with moving seedlings from their baby growing pot to their grown-up veggie garden location, look to eggshells to help you out!

Starting veggies or flowers from seeds indoors is a great way to get an early start on your outdoor garden when the weather is still cool. But that transition from indoors to outdoors is hard on the baby plants. This growing season, try using eggshells as your seed nursery! Crack your eggs high on the shell when you use them, and wash out the bottom half in water afterward. Then, prick a needle through the bottom to make a drainage hole. Fill your eggshells with soil, and use the egg carton to keep your seeds organized and upright. When your baby plants are ready for transplanting, crack the eggshell to move the plant—no pulling on the tender shoot to get it out of its growing pot needed! Note that this method is best for smaller plants such as herbs or succulents.

half eggshells filled with soil and growing seedlings beside yellow watering can

Eggshells as Fertilizer

Mature plants can also benefit from eggshells which can replace lime as a soil amendment. Calcium is especially helpful for tomatoes and can help to reduce tomato blossom end rot issues. It's best to do a soil test to see if your soil could use a pH boost. If you're growing blueberries or other plants that like acidity, don't add eggshells to that soil.

For the shells to have an effect in your soil, you need to essentially turn them to sand, according to the Alabama Cooperative Extension System. The best practice is to rinse out shells in the sink and then dry out eggshells in the oven at 250 degrees for ten minutes. Then, simply grind them in your food processor or blender. From there, add your eggshell sand to the existing soil and mix well.

The Los Angeles Times also shares how you can feed your flowers with eggshell tea as an all-purpose fertilizer. This won't add as much calcium to the soil, and the plants will just take what they need. To make the tea, rinse your eggshells in the sink to remove all the actual edible egg insides. Once you've collected a few shells, just pour boiling water over them and let steep until cooled. Fish out the eggshells and use the tea to water your plants as you would normally.

Eggshells for the Birds

As previously mentioned, eggshells are made of calcium, and mama birds need a lot of calcium to make their own eggs! The Audubon Society encourages bird watchers to add eggshells to their bird feed during the nesting season to help wild mama birds. The group says to make sure to dry out the eggshells in the oven, just like you would before turning them into sand. But once cooled, only crush the shells to about the size of the bird feed you usually provide. You can do this easily with a rolling pin. Then, mix the crushed shells in with your seed. The Audubon Society also recommends spreading some of these shells on the ground for non-seed eaters such as robins.

twp birds gather at a wooden birdfeeder

Now that you know how to use eggshells in the garden, you can give your plants and neighborhood birds a little boost and put those shells to good use!

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Why It's Good

Considering how you can use your waste as a resource is a great habit to implement into other areas of your home, too!