Only one of my hens is laying...

[wdspiller]

Hello all!
I am rather new to owning chickens, we bought 5 a month ago and only one has started to lay. They came from a farm with MANY chickens and I'm not sure if they are as young as we we told, I was just curious if you could tell age by the size and color of the comb. I know there are general health signs but wasn't sure about age. My hen that is laying has a large red comb and the rest look like this...

. They seem to all be very healthy and happy! Any ideas or thought are very appreciated!

 

[sourland]

When the combs on the non laying birds increase in size and become a bright red they will be ready to start laying. They all mature at varying times.