4 hens aren't laying... normal?

[534EBC]

I have 4 hens (3 RIR and 1 a plymouth rock). They are molting. I haven't gotten an egg in about 3-4 weeks. We got these 4 girls from a friend, who was moving from the country to the city. They are probably 4-6 years of age. We've had them for about 2 years now and never gone this long without egg laying. I haven't changed a thing. They have access to fresh water daily, eat a layer feed w/ oyster shell, have a clean coop. They free range daily inside a fenced enclosure. To my knowledge nothing had traumatized them. We do not use artificial light in the coop (and the other person did). Last fall & winter they still were laying. I've been told sometimes they go "off laying" from Fall to Winter, without the artificial light. Should I be concerned or let nature run it's course? The plymouth rock hen is the oldest and she had a fairly severe molt recently (and didn't last year). I'm fairly new to this backyard chicken farming so think it's probably normal. Some of you seasoned farmers need to advise this newbie. Thank you.

 

[Skylercarr]

They will not lay when they are molting. Since they are old their molt will take longer.