What is the longest you have had a hen sit on eggs and still hatch? As in, past Day 21.

[Lori J]

I have heard cooler weather can delay hatching. So what is the longest you have ever observed? (Either under hen or in an incubator)

 

[CluckerFamily]

I had a broody hen sit on eggs until day 24 when the last of the fertile eggs hatched.