Are eggshells good for plants? You bet your Aglaonema they are. Although nitrogen, phosphorus, and potassium make up plants’ primary nutrient needs, calcium is high up on the list of requirements for thriving vegetation, especially in the case of building strong cell walls (throwback to high school biology class). Coincidentally, eggshells are one of the most bioavailable sources of calcium. Being a better plant parent and reducing waste in your home sounds like a win-win, no?
Making eggshell fertilizer isn’t quite as simple as tossing a few eggshells into your beloved Monstera’s pot and calling it a day. Calcium has to be in a readily available, ideal state for absorption in order for your houseplants’ roots to soak it up. So simply crushing a few eggshells with your hands won’t do the trick, either: instead, you’ll need to take the time to clean, dry, and grind the eggshells into powder. It doesn’t take much effort – and all you need is a food processor, blender, or coffee grinder – but your plant babies will thank you.
Okay, so step one is technically to fix yourself some soft-scrambled eggs on toast or a frittata loaded with veggies. After all, you have to eat a few eggs to get to the shells. Once you have a dozen or more eggshells saved up (you can store them in a bag in your fridge throughout the week), it’s time to wash them. Use warm water and your fingers to rinse each eggshell inside and out, ensuring that there is absolutely zero egg white or egg yolk residue left. No need for soap. Give ‘em a sniff and make sure there’s no odor, then lay them out on a kitchen towel overnight or until completely dry.
Once your eggshells are dry, it’s time to grind. Place them in a food processor, blender, or coffee grinder and pulse or grind until the eggshells are the consistency of a gritty, somewhat coarse powder. It doesn’t have to be super fine or uniform; aim for the texture of coarse coffee grounds. Transfer to a reusable container or lidded Mason jar.
To fertilize an already established and potted houseplant, mix a few pinches to a couple tablespoons (depending on the size of your plant) of eggshell powder into the soil at the top of the pot. Do this right before you make the weekly water rounds, as this will promote absorption of the fertilizer. Since you rinsed the shell thoroughly before grinding, any nuisances like odors or pests shouldn’t be a problem. Just don’t fertilize with your eggshell powder too often; once a year or every few months is plenty for most houseplants.