Hens 1 yr. old just started to lay.

[myway57]

I have 3 barred rocks that are about 3 weeks shy of 1 yr. old and they are just now starting to lay. I have 3 different shape

(fart) eggs, what can cause them to start so late. all my other hens have been laying?

 

[Rainwolf]

My guess is Winter.
If you have a lighted coop and run extra "daylight" they might start laying earlier but most pullets who come to maturity in the winter will delay laying till they get more light per day.