Egg shells make good, cheap, organic seed starting pots, and this can be a fun project for adults or children. Even if your household doesn’t normally use eggs, you don’t have to buy some just for this. You can ask friends and acquaintances for their old egg shells. Most people just throw these away or compost them anyway.
Save egg shells by cracking the whole, uncooked eggs as neatly as possible against a counter top. Colorado State Extension recommends breaking it so that the lower two-thirds of the shell remains intact to use as the pot. It’s okay if the break is not totally neat (and it likely won’t be). After dumping the eggs into a bowl or skillet, rinse out the egg shells in warm water under your faucet.
Remove the lid from an egg carton and discard. Place the rinsed egg shell halves into the egg carton.
Use a spoon to fill each egg shell half with potting soil. Fill the eggshell about three-fourths of the way full.
Fill a clean spray bottle with water. Spray the potting soil with a gentle mist of water to dampen it.
Use the eraser end of a pencil to make holes in the potting soil, one per eggshell, for the seeds; or, according to University of New Hampshire Cooperative Extension, you can just use your finger. Place two to three seeds per hole and lightly cover with 1/4 inch of soil.
Place the egg carton with the egg shells in a sunny area. Keep the seeds moist by misting the soil with the spray bottle--you’ll need to check the eggshells at least twice a day to make sure the soil is not dry.