What causes a soft shell. This is her first egg, she is a RIR and is 21wks old. I found the soft shell egg under the roost this am when I let them out of the hen house. My girls have been eating layer pellets for the past three wks and they get fresh greens daily with a treat of grapes with oyster shell in the run. My other RIR's eggs are hard shell, she has been laying for a week now. They are same age and free range. Does it take some pullets longer to get the hang of knowing when to lay?