My daughter’s recent science fair project was super fascinating for gardening enthusiasts and wannabe homesteaders. Discovering through research that plants need calcium for basically all processes to develop and grow healthily, she hypothesized that adding eggshells to soil would help plants grow taller. She wasn’t sure if adding crushed up eggshells directly into the soil (not composting first) would prove fruitful, but she found online that many home gardeners do just that. After setting up 4 grow cups with plain soil and 4 grow cups with eggshell-amended soil (5 gm of eggshells each), she planted four Purple Cherokee tomato seeds in each cup. Her experiment measured the growth of the plants in both soils over the next seven weeks. Intriguingly, her hypothesis was wholeheartedly supported by the results. After growing the plants with all other variables constant, the plants in eggshell soil grew to heights of 14 cm, 16 cm, 16 cm, and 18 cm, while the plants in plain soil grew to a shorter 8 cm, 9 cm, 10 cm, and 10.5 cm. If ever there was an argument to add eggshells to your garden, this is the one!

I’ve gone back and forth over the years with throwing eggshells into the composter, but I’ve never added them directly into the soil. I’m officially sold on the practice. Obviously her experiment didn’t follow the plants all the way through to maturation, but her results are enough for me to regularly collect eggshells and add them to the soil when planting seeds. Especially since we raise our own hens, it’s a perfect way to leave a lighter footprint on our space in the world!

For the gardening nerds like me who might be geeking out right now, or if your student simply wants to replicate her experiment, I’ve included a picture of her science fair board. HERE also is a google doc with the information that she added to her board. She won second place and received so many compliments on her work, as well as for her presentation of the experiment. Needless to say, I am INCREDIBLY proud of her. She is such a cool cat and she was so diligent about taking care of her baby plants. It was such a fun project to help her with … and the fact that she is catching the satisfaction of growing food just makes my heart swell.