First I saved my breakfast eggs and only cut off the very top of egg.
Once I had 12 I made 2 small holes in the bottom of each washed and dry egg shell.
then I filed each one with a good potting soil mix and placed back in a egg carton tray.
I added the seeds, In this case Coriander / Cilantro and lightly watered.
I placed the carton with eggshells in a tray and filled with water so it could self wick and keep moist.
Watch my video to see the process.
Search eBay for Coriander / Cilantro seeds
The Coriander / Cilantro in egg carton now ready to plant
Ready to be planted in my balcony garden
Crush the shell before planting
The egg shell seedling planted in garden