The Natural Remedy That Will Help Your Hydrangeas Thrive With Colorful Blooms

If you love bigleaf hydrangeas (Hydrangea macrophylla) and want to make your hydrangeas red or pink, you need alkaline soil. Your hydrangeas grow perfectly fine in acidic soil, but people often add garden lime (calcium carbonate) to raise the soil's pH and turn hydrangea flowers from blue to red or pink. But rather than spend up to $25 on a bag of garden lime, you can create your own remedy using the remains of a food that you may already eat: eggshells. According to a study published by the journal Inquiry-Based Experiments in Chemistry and adapted by the University of Pennsylvania, eggshells are 94% calcium carbonate, so they are just as effective as garden lime in changing the pH of your soil. Rather than relegating your eggshells to stinking up the landfill, why not make your own fertilizer? It's a cheaper and more sustainable way to produce calcium fertilizer than the industrial process of limestone mineral extraction.

Americans eat a lot of eggs. Per the U.S. Department of Agriculture (USDA), Americans eat an average of 250 eggs per person each year. It will take a lot more than a few crushed eggshells to turn your hydrangeas pink, but it's a pretty easy process. Simply wash them, bake them, grind them into a powder, and sprinkle the powder around your plants. Don't expect immediate results or a one-time solution. It takes a while for the calcium to make its way down into the plant roots, and you may need to reapply your eggshell powder fertilizer throughout the growing season.

Before you start making your fertilizer, make sure you need it. Not every type of hydrangea changes color by adding calcium – only bigleaf hydrangeas – and your soil may already be alkaline enough to produce pink blooms. You can take a soil sample and test it with a soil pH meter, which you can find available at most garden centers. If it comes out acidic (under 7.0) and you want pink blooms, apply an eggshell powder fertilizer.

At 5.5 grams of shell weight per egg, you'd need the powder of 82.5 eggs to produce a pound (approx. 454 grams) of fertilizer, but depending on your soil's pH and how many hydrangea plants you have, you may need far less than that. Start with a batch of 20 eggshells to get the hang of the process. To kill any bacteria, rinse your eggshells to remove any egg white or yolk, place the eggshells on a cookie sheet lined with aluminum foil, and bake at 250 degrees F for about 20 minutes.

Alas, it's not enough to just break up a handful of eggshells and sprinkle them around your plants: Eggshells decompose far too slowly to have any short-term effect on soil pH. Use a coffee grinder, food processor, or blender to create a fine powder. Transfer your powder to a storage container and store it in a cool, dry place until you are ready to use it. In spring and again in fall, sprinkle a cup of your eggshell powder around the dripline of each plant and water it in.