What I learned:
1. It would be better to break the egg at the narrow end of the shell for a deeper "planter."
2. The egg shell planters dry out quickly.
3. It is easy to over water.
4. Hatching lettuce is fun.
I'd call the first part of this experiment successful. I'll be planting the first two shells in the cold frame tomorrow. I plan on smashing the egg up a bit.
I like how this looks with a few leaves.